OK start the ball rolling on a hardware store design CNC router.

Well, here we are in the hardware store design thread... Does that mean another black pipe design? Or is there a better option?

I'm not sure we want to go backwards to drawer slides...

And it'd be mighty difficult to do a conduit design like Ger21, cause we don't have a cnc machine to cut all the parts with.

Are we talking improved black pipe designs? Fixed gantry? Moving gantry?

Your thoughts...

Mike...

Hi Milke,
As a newbie with no machinist knowledge but plenty of electronics and lab experience, I've been forced to use the local hardware as a major source of raw material.

For me small means a small workpiece, so it makes sense to move the work not the spindle. I'm heading for a 2.5D axis setup with the z axis movement of the workpiece coming from a separately controlled arm. But I would put the z axis movement on the fixed gantry if I needed to use the spindle in 3D.

As the only source of steppers at the moment is old printers or ebay(limited funds) the timing belts will give me my transmission.
I do have a supply of old display framing - aluminium extrusion - so I plan to use 19mm chrome steel tube ( wardrobe fitting dept) epoxyed into the channel. This will be bolted down onto an offcut slab of formica clad 38mm kitchen worktop.
I'm using miniature bearing from the scrap box augmented from ebay, but would try skate bearing otherwise.
Any thoughts?

Drawslides work pretty good for the X and the Y. You can even you steel wire wrapped around a plastic wheels to move the gantry, like pulling a curtain.

Buying your hardware from ebay is definitely a good option.

As for using the components that you've gotten out of old printers, you'd have to include some photos and descriptions so that we could better understand what you have.

Mike...

Hi Milke,
I've been forced to use the local hardware as a major source of raw material.

As the only source of steppers at the moment is old printers or ebay(limited funds) the timing belts will give me my transmission.
Any thoughts?

I'm looking to build a machine using drawer runners. I've located a source with 450mm travel and minimal play in the bearings (heavy duty ball bearing runners).

I've got plenty of stepper motors now from 100oz in upwards and some toothed pulleys/timing belts.

Just need to build a workshop to house it all in before I can start building the machine.

hi
I am currently building a machine , mainly using MDF , but i guess the problem is some of the parts , like 20mm*20mm L section steel at 3mm thick that im using for the runners and supports and 20mm stainless steel bar for the bearing slides, are not available in most hardware shops , (but are available on the web ) and bearings are a problem also,

i thought about using unistrut , that is an excelant matirial for making the frame work , even if a tad expencive , but would require minimal machining
and m10 threaded bar for the lead screws

although i guess all the bits are not available from the big diy hardware stores here in the uk like B&Q and homebase ,but i have found that CEF(city electrical factors) in the uk (have shops in almost every major town) stock items like the treaded bar and unistrut and fittings

i designed my machine to use minimal machining as i only have access to a electric hand drill and the router that i am going to use as the cutting tool and hand tools like saw, file

sorry no pictures yet and its still a few months off compleation but looks like its going to be finished within the £400 budget i set for it and its got a workspace size of 900mm*500mm*100mm

i originally started with the same idea that i should be able to get all the parts from the local diy/hardware store but in the end found that way too restrictive on parts , threaded bar for example was not available , and local steel stock holders can supply steel some places will cut it to lenth also

i can only speak for what the uk hardware stores will stock , and not shure whats available in stores elsware things like good quality draw slides for example are not available

i need to solve a dfx export problem with my cad package (total cad ) to get the fonts right then i will post my design

Dave

My first machine used a combination of drawer slides for the X axis gantry and ball bearings and gas pipe for the Y axis table. I like the drawer slides and am in the process of modifying the table to use slides.

The combo I have worked out is one heavy duty full extent slide mounted 180 degress around and on top of another slide. This means that the table will always have support and the travel is obviously doubled. This will be interesting to test.

mikeschn,

Ger21's conduit design can be done without cnc If you have a good router and a laminate trimmer bit with a bearing. All you have to do is make a simple jig to hold the form that the bit follows & the work piece.

This reminds me of the Dave Gingery books. He talks at length about how some one had to build the first one. It's the old "which came first the chicken or the egg." In this case it is the egg because without the egg you can't make the chicken out of the hardware.:)

Also the draw guide system is not that bad. For a first time machine and a learning experience, I believe most beginners would be very pleased with the machine. I have read about many machines getting 1/32" accuracy from drawer guides. This is far more accurate than most cabinet shops could ever hope for.

I am a newbie my self and I do not have an unlimited budget to build with so I really hope that people will come to the cause with some new "cheap" ideas for the beginner.

Thanks so very much
Jimmy Southern

P.S. don't be afraid to throw out very crazy ideas, sometimes they work!! (group)

Having built a few machines now and used several different hardware store solutions for the slides, I would say that the number 1 consideration is rigidity.
This being said, the easiest way to make a rigid machine is to make a small machine. Drawer slides can work OK on a moving table if the travel is kept small enough. Drawer slides on the Z axis do not work well at all though, another solution is necessary there.
Also a moving table design with a fixed gantry will be far more rigid than a moving gantry design.
So, if I may suggest, lets work towards a small (8" X 12" travel??) fixed gantry moving table design.
Colin

Wow, I didn't realize there would be that much interest in a drawer glide cnc router.

Do we have 2 cad users here that would be interested in working on a drawer glide machine?

Mike...

mikeschn,

Ger21's conduit design can be done without cnc If you have a good router and a laminate trimmer bit with a bearing. All you have to do is make a simple jig to hold the form that the bit follows & the work piece.



Doesn't the laminate trimmer force you to cut the entire 3/4" thickness at one pass? Can you cut that much plywood or mdf at one pass?

Maybe we should look at a pattern bit.

Mike...

Doesn't the laminate trimmer force you to cut the entire 3/4" thickness at one pass? Can you cut that much plywood or mdf at one pass?

Maybe we should look at a pattern bit.

Mike...

He said router and flush trimming bit, he just was a little unclear. :)

A faster, easier way if you have a table saw and drill press:

Use a sliding cutoff sled with a stop to cut all your parts the same length.
Use a fence on the drill press with stops to make the cutouts for the pipes. Use a forstner bit.

For those of you in the UK who want decent quality drawer slides check out www.buller.ltd.uk - speak to Rafael - he's a really nice chap.

Go to Miscellaneous on the left hand side and Runners/Slides - you'll pick up a 500mm length runner for £3.84+vat per pair and up to 700mm for £7.98 a pair and they are pretty reasonable heavy duty bits of kit :)

Gerry,

Thanks for the correction on my post. I was in a bit of a hurry when I typed that.

If you are going to use the flush trim bit idea you will have to remove some of the waste material first and of course rough cut to length & width. But I would use one one master template for all of the pieces for each area to have consistency.
this willgreatly reduce the errors from operator input.

hope this helps
Jimmy Southern :)

I'd suggest you make it a rule that you keep the scope as the title "hardware store design". As example it is reasonable to expect you can buy gas pipe or drawer slides, mdf, drawier glides, rollers at a hardware store. I can't say I've seen IGUS or Thompson parts at one.

I agree with pminmo.....before we muddy up this site...perhaps we need separate threads...one for "hardware store design", 2nd for "gantry with rails"....you kinda have skill level categories....instead of requires 2hammers...we'll have have a machinist rating like "2 mills" with a 1 being the minimal amount of tools, 2 being need access to a mill, 3 being need access to mill & lathe....

...we'll have have a machinist rating like "2 mills" with a 1 being the minimal amount of tools, 2 being need access to a mill, 3 being need access to mill & lathe....

Most people will be more likely to have table saws (maybe) and drill presses. Very few will have mills or lathes, imo.

And there are a few different forums set up already. But yes, some ground rules need to be set up quickly.

I agree with pminmo.....before we muddy up this site...perhaps we need separate threads...one for "hardware store design", 2nd for "gantry with rails"....you kinda have skill level categories....instead of requires 2hammers...we'll have have a machinist rating like "2 mills" with a 1 being the minimal amount of tools, 2 being need access to a mill, 3 being need access to mill & lathe....

I agree with both of you. The hardware store design is exactly that, with all parts coming out of the hardware store. I went back and re-read the posts, and I can't see where the conversation was diverging, and maybe it didn't. But your point is well taken.

We also have threads for a cheapcnc design and a mid level design. That's where it starts getting less clear. For a mid level machine, do you assume access to a mill and a lathe? I like the mill code you started up there... I would suggest the ratings 0 mills, 1 mill or 2 mills.
0 mills is just basic tools, 1 mill is access to at least 1 mill, and 2 mills is access to a mill and a lathe.

With that in mind, the cheapcnc, the 80/20 and the hardware store designs can all be 0 mill designs. The midrange machine can be a 1 mill design, where a person is using his entry level mill to create the masterpiece he really wanted in the first place!

Mike..

Guys,
When you say hardware store supplies, does that mean exactly what it sounds like, or are bearings included? The reason I ask, the local Princess Auto store (think of it as a small town store that caters to farmers) carries almost everything a hardware store does, plus surplus parts and bearings and steel.
Using what they sell, I have built several different machines cheaply, using fairly basic hand tools plus a drill press.
Combine them with Home Depot, or your basic building supplier, and you have everything you need except software and the electronics.

HTH
Iain

Exactly... hardware store meaning your local home depot plus your local ace hardware, or equivalent. You gotta make an assumption that stores like these are more or less readily available in all countries, and the parts are reasonable priced, in various countries.

Of course there will be differences, and the builder will have to adapt... but hey, that's what makes building these fun!

Mike...

Where's all the CAD users? :confused:

Mike...

This is exactly what I am looking for. The machine I would want doesn't need to be super huge, infact 2' by 2' would be the biggest that I would need (and might even be too big). Most of what I would be CNCing would be anything up to 3/8" Balsa for wood and up or 1" in EPP foam. I would be ok even using a dremel as the cutting tool. You guys should setup a limit as well for travel/working/table size?

Mike,
Thanks, that clears it up for me then, as the only parts I can't get at Depot, Ace, or TruValue are the bearings. However, I can get the all thread, tubing, or aluminum angle at any of the above, and if you go to the housewares section you can also get those nice white nylon/polymer cutting boards that are great donors for slider pads. Line a piece of alu angle with it and use a piece for the rear and you have a decently simple, ridgid guiding way. Works a treat on the Z axis.
It's low profile too!
Or, using pipe or extruded tubing, and V groove pulleys you can make a decently cheap, simple and accurate moving table for larger size routers.

The possibilities are endless!!!

Iain

Hello Everyone,

I just have a few suggestions. Don't rule out the skate bearings. there are so many creative ideas available that use them. IMHO you will be severly tieing your hands if you do. Most people that visit the Zone use ebay regularly and even though I have heard some comments on the quality of most of the bearings on ebay they will still beat drawer guides hands down. For those that are in the hard to reach parts of the world I would still recommend the bearings. I have seen buy it now prices of $20.00 for 100 bearings. even if you were getting the drawer guides for dealer cost you would still have a horse race on the price issue, even with international shipping. Metric countries especially should love the skate bearings because they are an easy score for the bolts and hardware needed. We in the U.S. have to special order bolts to fit these bearings, or improvise.

What I would like to see is some "KISS method" designing. Keep the complicated rocket science ideas to your self. But also on the other end I don't want to see some 8th grade erector set science experiment.

Bottom line: we all should have a few simple tools in the inventory before we consider building a cnc machine, not to say we have to have them, but the guys who will be designing this will. We will have to expect a small investment in tools. Here are the tools I think are mandatory.
1. hand drill
2. circular (skill) saw
3. decent set of taps & dies
4. good scribe for marking hole locations
5. good square
6. at the very least a laminate router and a good assortment of bits
7. Assorted wrenches and hand tools

Here are the tools that I think are worth the investment. Notice I said "INVESTMENT", these tools will probably be passed down to your children. So get the best you can afford.

1. drill press. even if all you can afford is the ebay $20.00 special it will be far more accurate than you will ever be by hand!!!!! MUST HAVE!
2. table saw. not a must have but again far more accuracy!!!!
3. router table. If you can't afford the table saw then go with the router table at least. This is the least appreciated tool in the shop until you need it. Also contrary to popular opinion a router table will work with a good laminate router.

Don't expect to design something for the general newbies that we can build with a hand saw and a screwdriver, because you will alienate the general population of readers that would like to build a first time machine. I speak from experience because I am a newbie. I know it costs to learn anything that is worth while. Just keep the non hardware purchases cheap, available and easy to use.

Sorry for the rant :D I will now step quietly off my soap box and listen to the next speaker.
Thanks for all that you do for us newbies it is appreciated (group)

Jimmy Southern

KISS rules!!!!!! long live KISS! :-)

Jimmy,

I've build 2 small and very cheap machines using a combination of drawer slides and nylon guides.
The skate bearings are probably better, I have looked and thought about it but:
I do have the tools you mention (even some more) but don't see how I could build any of the axis using bearings and obtain the same precision.
Found several examples on the net but they all look too complex for me to build.
The drawer slides I use are Accuride one's recuperated from mini computersystems.
They are 35mm wide and ride very smooth, using 2 of these 20 cm apart gives an almost perfect axis and above all: it's dead easy to assemble.
Of course there are drawer slides of different quality.

BTW: I have a lot of bearings here, several sizes and still would like to give it a try, just don't know how to start.
Any pointers to something easy?

Luc.

My 2nd 2 cents :-). Drawer slides vary, what might be available one place may not be the next, and different manufacturers have different dimensions. And while rollerbearings may not be available at a hardware store, they are available retail, mail order and off the web, all around the globe. But they present a little more difficut problem of drilling well placed holes, or adding complexity with adjustments. I have been impressed by some designs here that use roller bearings and flat, angle or tubular stock. Attached is an example. While this machine is what I would consider out of scope for this thread, maybe the captive bearings and tube stock are not.

CADman here .. can do drawings ... please find attachments to see if you can open ...
dxf for older doods

Guys,
I too have read through the previous long attempt which just lost steam.
I am well into building a Jgro Machine so can't say how well I will be satisfied with the operation but the plans were great. I did use the former recommended list of tools without having seen the list at that time ( it didnt exist).
ie Drill Press
Table Saw
Router Table
& Hand Tools

I did not have access to any Machining capability but tried to accurately mark and use the first piece as a template using 1/16" drill to drill the first holes and using others to keep each piece aligned with the template as I drilled more. Center routed Dados were achieved routing from both sides. I mention all this to amplify that with patience and limited equipment it can be done.

Now on to the existind topic Everyone's comments even Jgro's seems to be that it is not stiff enough. All the engineering discussion concerning solid steel rods also points to the fact that these are only marginally better than Pipe of the same dimension.
Therefore a method is needed to stiffen them up.

Along comes Spalm's Design

http://www.cnczone.com/forums/showthread.php?t=12056

The Jgro plan could be easily modified in the torsion box aera with the linear bearings inside the gantry for the design. Or with Spalm's permission using his design and adapting it for the opensource requirements smaller or larger. Spalm's problems were as I understand bedding the rails (the solution seems to be fibreglass and cling wrap) and stiffening up the Gantry Sides. Either Stringers as he has done or what about double thickness Ply or MDF.

Please for the sake of the budding builders counting on the forum for the best posible solutions, which I know collectively we could achieve, don't have a particular axe to grind and let the discussion bog down and stall.

Those of us who have particularly set Ideas are the ones who least need the plans for the opensource machine as they could do their own on the fly.

Ok I'm off my soapbox now.

BTW although I'm a Nubie CNCer I am reasonably proficient in AutoCAD.

cheers

HI, I am glad that you guys are taking up this task to develop a good homebuilt cnc machine. I have been searching all over for a small cnc router that can cut wood and aluminum, and the cheapest I have found is made by Liberty cnc out of Tennessee, www.libertycnc.com. It sells for about $3500. I own a small part time business and I really could use a good machine. From talking to the guys at Liberty cnc, I learned that you need a slower speed to cut aluminum, grade 3003 or 5052. They sell a Trend brand router for such application, and it has 5 different rpm settings from 8000 to 23000. I do have a good tablesaw, drillpress. I don't know much about cnc, but if you can tell me what I need I can build it. I think this is definately a good thing that you all are doing here. Thanks for letting me give a small 1cent worth.

Gday all from Australia, I have not done anything yet with building a CNC machine, but
I'm looking into it for next year project.

I used to work for a company that ran a trumph cnc punch press. I programed, ran, repaired (mechanically) this machine.

I have found some supplyers of some interesting hard where and will be looking into for some of the parts needed for this prodject. http://www.tea.net.au/

Regards
Brett Fisher

Hi to any one that is out there my name is Dave I am English a cad draftsmen using acad. 14 and wood be happy to help with any drawing and design. I live in France and this will be my first CNC machine. I am looking at something more substantial than drawer runners and have found a supplier of engineering parts,hpceurope.com that are happy to supply small orders. the prices of the liner bearings are more expensive but the basic frame of your machine will be solid, there is also a dxf cad Libby of parts in 2D so you can just insert them in to your drawing

HI, I am glad that you guys are taking up this task to develop a good homebuilt cnc machine. I have been searching all over for a small cnc router that can cut wood and aluminum, and the cheapest I have found is made by Liberty cnc out of Tennessee, www.libertycnc.com. It sells for about $3500. I own a small part time business and I really could use a good machine. From talking to the guys at Liberty cnc, I learned that you need a slower speed to cut aluminum, grade 3003 or 5052. They sell a Trend brand router for such application, and it has 5 different rpm settings from 8000 to 23000. I do have a good tablesaw, drillpress. I don't know much about cnc, but if you can tell me what I need I can build it. I think this is definately a good thing that you all are doing here. Thanks for letting me give a small 1cent worth.

Hi chip sweeper
If you have a look on the net for porter-cable routers you will find a router that is built for DIY cnc the model no is 7518 it has a 3¼ peak hp motor and is 5 speed
www.porter-cable.com

It looks like we have 3 autocad users in this thread. Excellent. We'll be starting to draw soon!

In the meantime I am sensing that we have two different designs developing...

1) with drawer slides
2) with supported black pipe and skate bearings

The drawer slide design is definitely a smaller design, call it desktop if you will, and will probably have a machining area of 12" x 12" or thereabouts. It can probably be machined completely on a table saw, and assembled with some hand held tools.

The supported black pipe design is a little more complex, but should be a much more rigid machine, even more rigid than jrgo's design. It'll be similar to ger21's torsionbox design or spalm's second mdf machine. This design requires a bit more tools, table saw, drill press, router with pattern bit, etc...
The machining area is much larger on this machine, probably in the area of 24" x 36".

Is this the right direction for two hardware store designs? Your thoughts?

Mike...

The 24x36 does sounds quite a bit more appealing to me. Supported black pipe and skate bearing should be easy to come across here in Arizona.

I do have a nice band saw, drill press, and router. The only I do not have is any welding equipment if it is needed.

Hello Everyone,

I just wanted to put in my vote.

NO to the drawer guides
YES!!!! to the pipe & bearing machine

I do believe that jgro's machine is a very good start but I have seen modifications that would make it better. The 24"x36" cut area is a perfect size for a starter machine. You could use the hobby CNC kit for the electrics IMHO. This would keep the learning curve low, especially for the electronic illiterate, like me.

One idea I saw that would make this easier, is the eccentric bolt for the bearings. This particular design was very easy to produce, even for the novice. You simply take a bolt 3/8"-1/2", whatever size we determine will be most suitable, and offset drill and tap a hole for a 5/16 flat(flush) head stove bolt in the head of the large bolt. This should all be available at the hardware store. It is also very simple to understand. This would give a great deal of play to take up errors, and give alignment ability.

If any one has a link to the pics of the bolt idea please post the picture. I saw it somewhere in the forum but did not save the link.

With a good torsion box bed and gantry, full support for the pipe or rod, whatever we end up with, I believe this will be the next starter machine for the newbie just coming to the zone.

I am going to try to build whatever we come up with. I really appreciate what jgro designed but I believe we can make it better.

Watching & waiting on pins & needles
Jimmy Southern

I'm looking for a good way to secure the black pipe to the torsion box. We could JB Weld it... but then we can never take it apart. We could drill some holes in the black pipe, and use socket hd cap screws. Is this still in the realm of entry level hardware store machine?

Any better ideas for fastening the black pipe to the torsion box?

Mike...

Mike,

I like the capscrew idea but I would like to see a tee nut set in a pocket, or hole, like people have been doing on the jgro pipe supports. It would be easy to use a forstner bit to make the hole for the tee nut. You could even use a hole saw or spade bit, whatever you have. This would be much easier & stronger than tapping the MDF.

Everyone please jump in with any other Ideas,
Jimmy Southern

Don't you need some adjustability....some time back we came up with the idea of supporting the ends of the pipe with some adjustable bearing blocks.

You mean like this?

http://www.cnczone.com/forums/showthread.php?p=98533#post98533

Mike...

Viper,

If I am understanding you correctly, on the adjustability, I think if you use a master template to route all of the pieces then the only adjustment that should be necessary would be to the bearings on the gantry & the z carriage. Everything else should be very consistant. You may have to shim in a few areas but I don't think you would if you assembled the machine carefully, paying close attention to the alignment of the pieces and to the squareness of the parts.

If the design is well thought out it should go together almost like lego blocks. We should design this to have half lap joints in the torsion boxes so it goes together like a drawer divider. this will greatly eliminate the build errors.

Hope this sheds some light on the idea that I have
Jimmy Southern

May I suggest that if your going with black/gas pipe that you size it to commercially available cutoffs. Usually available in 1' increments. For a machine base, consider using 3 sheets of MDF glued/laminated, that will give you strength and weight for stability. Those that don't have a table saw will be pressed to do a good torsion box. The only thing you need there is a flat surface or jigged support.

what happened to the KISS principle .. and also First things First.. the simpler contains drawer slides, smaller, cheaper and less complex ..

it makes common damn sense to see how the simpler proof of concept can be completed before undertaking the whole gas pipe and roller blade bearing design..

start small and go forward.. remember, "He who is faithful in a little, can be faithful in alot."

Well actually, we are going to do both, the drawer slide and the black pipe designs. Both designs will be hardware store based, and also no mill required.

Here's what I am working on for the black pipe design. Each member of the torsion box will have an end like this, for adjustability over the entire length of the black pipe. Furthermore, if the holes are not perfectly centered, that's okay, you can center the pipe using the screws. The pipe is going to be 1 1/2" black pipe, currently 3.39 per foot, which has an od of 1.9". So you can drill a 2" hole, and have .10" to play with.

What do you think so far?

Hi, I am going to try and add a simple thought here, I think Jimmy is refering to a dado groove in the torsion box. Regarding the alignment of the pipe holes in the torsion box, once you measure, mark, and drill the first end piece accurately, you can lay it on top of the second piece and sqaure and clamp it. Then your first piece is a template for your second piece and should give you perfect matching holes.
As a possible substitute for the black pipe, has anyone looked at the ceiling fan drop rods that have a polished finish and are sized from 6" to 48"? If so, what did you think?
Thanks, woodworker21

Hello everyone,

Just need to clear up a few things. First I am greatfull to Mike for taking the lead on this. There has been some discussion on the drawer guide vs black pipe and I was glad to hear that we are going to design two different machines. Personally I have no use for the drawer guide machine, it is just too small, so my mind is centered on the larger machine. So don't take my lack of interest as oposition. I am just posting the ideas I have had or seen.

Now to the specific misunderstandings: The half lap joints are nothing more than half depth dados. Please look closely at ger21's new machine thread. This will clear up alot of questions about what we are talking about.

Now to the difficulty: I am just guessing here but I think there would most likely be no more than 5 pieces that would have to be precision cut and all of this can be cut with hand tools if very diligent. More tedious than difficult. Once these pieces are cut you simply use a pattern bit, or flush trim bit, to follow the master template. It seems more daunting than it is.

I would like to see the design team take this machine to the level of ger21's machine just use a little less material and make the plans include either scalable master patterns or very precise measurements. The only variables that should exist would be the thickness of the MDF, Ply or whatever the builder uses, and the available pipe sizes. this will greatly reduce the work that the builder has to do. This design is very scalable up or down and very rigid. Ger21 says in his post that he put his entire weight 220lbs (I think thats right, sorry ger if it isn't) and it only deflected 1/64". Jgros machine has nowhere near this strength. This is why I am pushing very hard for that direction. In my opinion ger and spalm are on the right track for the perfect "usable" machine.

I am very open minded if anyone has a better idea for this machine, but I have not seen anything that for the price gives the same quality.

I really hope that no one has been offended by my enthusiasm. I really do plan on building this machine so I would like to be the guine pig(not sure that is spelled right).

Thanks to Everyone!!!
Jimmy Southern

P.S. Keep the ideas coming (group)

i DID A little CAD of that nice Rib Mike --- please find attached and see if you
how it looks ...

Hi,

This end of the torsion box design may be unnecessarily complicated as Spalms design relies on the pipes being stationary, oK, (parallell and Level to the cutting surface} but so is the torsion box hopefully. All the adjustment is on the Bearings which in the case of the Gantry are moved in relation to the Gantry Legs (sides) the Torsion Box cut-outs must support the rail solidly to prevent the slight (but to some unacceptible) flex in the rails. These adjusters of course will do this but so will grouted ( for want of a better term ) with epoxy ends and the rails pulled into place. The end of the torsion box could be like shown with a screw pulling the rail into the opening.

However without a cantelivered end in the torsion box or leaving the bottom open it will be hard to adjust these bolts and reduce the cutting surface for a given size gantry. If the bolts are needed then it is possibly better to use countersunk screws from the outside. Must stay away from the bearing tracks though.

Spalm now believes he has cured the problem by pulling the rails together on the ends with allthread.

Hey guys,

I spent about a month trying to come up with an easy way to build these torsion boxes. The half lap dados are tempting, but just try to get them all in 3 dimension parallel (alignment) before the glue dries. I tried twice, and gave up. That is why is used the individual spreaders. Gerry’s boxes were a lot larger than mine and he used screws to hold them together. If you are trying to build thinner boxes, I found that the parts floated around a lot.

I used the base ply or MDF as the ‘base’. Double check this for square. If it was ¼ inch ply, I used double sticky tape to make it lay flat. Then I glued the first stretcher and checked for perpendicular while using my finger to make sure that it touched the 3 edges of the base. I then spread glue on the first set of spacers and squished them into place (placement is not important). I then spread glue on the second stretcher and squished it into place, again checking for perpendicular and using my finger to make sure that it touched the 2 edges of the base. Repeat this along the entire base. The last set of spacers never came out to the right length, so I custom cut them at this point to make sure that the last stretcher was just touching the far edges of the base. I then let this dry overnight before adding the second skin by applying glue and a weight to hold it in place until it dried.

I did not use a nail gun or other fasteners. Only glue holds the box together.

Just my $.02
Steve

The basic construction of a torsion box can be seen here...
http://www.diynet.com/diy/ww_materials_products/article/0,2049,DIY_14442_2278181,00.html

Chron,

Your cad drawing is a good start. The board is 3" x .75 thick. The upper and lower bolts need to be above and below the board.

I'll start modeling the torsion box this morning.

The other approach is to let the pipe lay on the bottom of the circular cutout, and just use the other two bolts to snug it up. The only reason you'd need the bottom bolt is if the cutouts are inaccurate.

When I built my sample rib, I found it very easy, because precision wasn't critical. And all 3 holes were very easy to drill and tap. Oh, and the drill and tap was available at the hardware store too, for $4.39. Throw it in your drill motor and away you go. I would harden the threads with some CA though.

Mike...

P.S. I threw a few lines on paper, to get a feel for where I am headed. The bolt size changed from #10-32 to 1/4"-20 (not changed on the drawing yet)!

Here's the lower torsion box and the skate bearings... I don't want to go any further until you guys tell me that's what you had in mind, and that we haven't created any weak links... :idea:

Mike...

P.S. Just added the centering bolts...

Mike, if you'd like, you can come by and take a look at mine.

Mike, if you'd like, you can come by and take a look at mine.

I'd like that! PM me your address and phone!

Thanks,

Mike...

spalm,

I was just reading your post and had a thought. If the pieces are cut like ger's, it should be a simple matter of putting together the outer shell of the box first. If this is square and true when the glue dries the rest should just follow it's lead. Also the assembly will only be as good as the master pattern. The more time spent making the masters perfect the easier the assembly will be. Just my opinion though.

Mike,

I did notice one thing I would change. On the bearing bolts I would go with a flush, or countersunk, headed bolt. This would give a bit more room for the supports to clear. It will also center the bearing on the bolt and take out any play in the bearing itself.

So far I like it!

Also did anyone find the eccentric bolt idea that I was looking for this might be handy for the cad guys if we can get them a picture.

See ya,
Jimmy Southern

About the best we could do is to go with a low profile socket head cap screw.

I'd like to see a picture of that eccentric bolt too!

Here's a major question for you guys...

do you want some kind of built in adjustment plate like spalm has, or do you want all your adjustment in the pipe adjustment blocks?

Mike...

I just dug out the pair of drawer slides I knew I'd scavenged some time back. Turns out that they are Accuride precision units rated 150 lbs the pair, with a retracted length of 28 inches. I'm going for a drawer slide design for my first machine.

One question for discussion. I am considering angling the mounts so that the slides are 30 degrees off vertical. This way I can assemble with preload without needing thousandths precision in construction. I'm also thinking that it will deal with sideloads better. Any comments?

Jimmy, I was just pointing out what I had learned. Note that Mike’s link on torsion boxes also uses individual spacers. Both ways work. Just watch out during assembly time. A couple of things that I was worrying about when building these were:

Most people at this level do not have a pneumatic nail gun. I do, but I was trying to build to their level of tools. I was using 1/2” MDF and screws at the cross joints did not work to well. Remember if you use Baltic birch ply, it is metric, so you may have to get metric router bits (or adjust cuts) for a good dado fit.

My most critical alignment was to make sure that the pipe seats were all in line and the box was square. This is a little different than normal box construction as the struts stick out.

Clamps just seemed to get in the way and can add twist to the box that you don’t realize until it’s dry.

I like where this is going,
Steve

My most critical alignment was to make sure that the pipe seats were all in line and the box was square. This is a little different than normal box construction as the struts stick out.



The top and bottom of my torsion box have a rabit along the edge with the tubes. The cross members are notched to allow the rabbit to fit in. By carefully adjusting the rabit, it can only go together perfectly straight. An alternative would be to cut a small slot in the cross members, and also in the top and bottom. Then use a spline during assembly to line everything up relative to the top and bottom skins. You could do this with a table saw or router table.

Gerry, my point exactly. All I wanted to point out is that these boxes are a little different than normal, and probably require some careful thought on how to assemble them.

Steve

Spalm, Ger,

You both have mentioned the technical aspects of the job, and I very much agree that this is not going to win the award for the easiest machine to build, but for the extra strength and rigidity I believe that most will agree when I say it will be worth it.

If we can put our heads together and be very thorough in the designing stage we will make a machine that will have the zone buzzing with new cncers(to coin a phrase).

My entire point for this discussion is: I have plenty of time to build the machine of my dreams, just no money. Also from what I have read and seen this machine can almost be scaled to a 4'x8' size without any loss of accuracy or strength. You can't say that about many other machines here. If we can pull this off it will be the best tutorial for the person who would like to build a solid machine for few bucks.

There are those who will say this is too difficult to build and you have to have a cabinet shop to build it, but I believe that what I have seen so far could be built with a jig saw, a router and simple hand tools. I have built much worse with alot less. In my opinion this machine will be technically easier to build than jgro's. It just looks more complicated.

Stay with it guys! We are on the right track!
Jimmy :cheers:

I just dug out the pair of drawer slides I knew I'd scavenged some time back. Turns out that they are Accuride precision units rated 150 lbs the pair, with a retracted length of 28 inches. I'm going for a drawer slide design for my first machine.

One question for discussion. I am considering angling the mounts so that the slides are 30 degrees off vertical. This way I can assemble with preload without needing thousandths precision in construction. I'm also thinking that it will deal with sideloads better. Any comments?

You won't have enough with just one pair...
If you build the system with moving X and fixed Y axis, then these are great for the X. (That's exactly what I did)

For the Y I used "the modified drawer slide" concept.
Below is a link to a picture of a test axis, it just gives an idea of how simple it can be.

http://users.skynet.be/sky50985/CNC/testaxis.jpg

The leadscrew is standard M10 threaded rod, the nut is home-made of nylon and the stepper directly coupled. On the opposite side of the stepper is a single bearing mounted on the frame and fixed with 2 nuts on the leadscrew.

I used a standard Accuride drawer slide and modified it, today I found these on the net:

http://www.cabinetparts.com/cgi-local/shop_2003.pl/page=acc_4113.html/SID=1124887696.24551

This is a US? based distributor but found several all over the globe, even in little Belgium here.
2 of these make a perfect Y axis.

I don't fully understand what you mean by 30 degrees off and what the advantages are. Think I have a bit of a clue, could you draw somehing up?

To obtain precise contruction, I did it as follows:
Screw one of the slides to the base plate, then mount the moving plate on the fixed slide and on the floating one, using slightly oversized holes then move the plate to one side and fix the screw on that side, the same for the other side.
The plate should now move freely over the entire lenght and all screws can be fitted.

Hope you understand what I mean, as said I'm from Belgium and English is only third language here.........(at least when I went to school a long time ago)

This is the best I can do on the eccentric bolt idea. This is also my first attachment. Hope it works.

Jimmy

Jimmy: "I believe that what I have seen so far could be built with a jig saw, a router and simple hand tools"

I agree. We should always keep the skill level of the target audience in mind, and at least offer them an option or a way to complete the job. I also do not think it will really be any harder to build than the other types.

Steve

Hi Lucas,

Could you, please, explain to me how did you modify the drawer slides? Eventually, send me an e-mail with the explanations. Also, please, post the link to sources of that "accuride" here in Europe. I am very interested in this solution.

Thank you for your help.

Zoltan

just looking at the tortion box design , kool

but i think this modification the the design of the rail supports may be a bit easier to make and uses 1 less bolt per support and may be a little easier to allign , but not too shure , what do you think

Dave

when thinking about building a machine i also thought about using a piece of angle iron rather than a tube or bar , i was not shure if this would be a good idea but theres a sketch of it attached ,

it would need a method to align it but the principle looks like less effort to make

Dave

when thinking about building a machine i also thought about using a piece of angle iron rather than a tube or bar , i was not shure if this would be a good idea but theres a sketch of it attached ,

it would need a method to align it but the principle looks like less effort to make

Dave

Square tubing might also be a alternative choice set into a V. The surface contact problem is then solved and one could drill a hole thru for a screw to help retain it.

Edit:
Then one could construct a jig to hold the router At a 45 deg. angle to mill the V in the torsion box once it is constructed. This would allow for a higher precicion placement of the V.

Square tubing might also be a alternative choice set into a V. The surface contact problem is then solved and one could drill a hole thru for a screw to help retain it.

Edit:
Then one could construct a jig to hold the router At a 45 deg. angle to mill the V in the torsion box once it is constructed. This would allow for a higher precicion placement of the V.


this would require a router and jig for it , thats why i thought of using angle section , if you did cut a v for it then you could use tube or bar that would provide a better running surface than flat angle iron or box , the problem is how to impliment alignment of it

it would be easier to align than multiple adjusments accros the lenth , maybe bolting the whole side piece using slotted holes may offer a way ,
if scaileing up the design is to be considered then having 1 suport every say 200mm is going to have a about 23 bolts to adjust on a 1m design
and a 3m design is going to have about 56 per side
thats got to be a pain and a long job to set up

i do think suport on the rails is a good idea , and the current design looks like it is going to be rigid and a capable machine , but tend to think that it could do with a easyer way to align it

hope im not stepping on anyones toes here

Dave

Hi Lucas,

Could you, please, explain to me how did you modify the drawer slides? Eventually, send me an e-mail with the explanations. Also, please, post the link to sources of that "accuride" here in Europe. I am very interested in this solution.

Thank you for your help.

Zoltan

Zoltan,

I found some distributors with google "accuride drawer slides", several in the UK and other countries but I didn't save them, I suggest you try Google.
Edit: look here: http://www.accuride-europe.com/locator2.asp?cat=ie&lan=english

For the modification:
I removed (sawed, drilled, grinded..) all stops and dismantled the rail completely, take care for the little balls, they roll very far and always somewhere where you just can't reach them anymore.

Cut 2 pieces of the outside part of the rail, let's say 25cm, this is the total lenght of the axis.
Then you need 2 pieces from the inner part for the mounting plate: 8cm in my case, file the sides where they contact the balls very nicely so that it can run smooth and doesn't strike the balls.
This results in a travel of 17 cm (25 - 8).
Now you need the ball holder section, this must be cut at 16.5 cm (17/2 + 8).
17 divided by 2 because it only travels at half the distance,speed of the inner part. This is badly explained, neither distance or speed is correct, can't find the correct term in English but i hope you understand.
Edit: distance is correct: if you slide the inner part by 10 cm then the ball holder only moves 5 cm.

Clean the whole thing up, reassemble, grease etc.

Result is a 25 cm slide with a 8 cm moving plate and always fully supported by the balls.
You can of course adapt these lenghts to suit your needs.

Remark: this works only for rails where the balls are kept in place when you remove the inner part, obviously. I have some smaller ones wich don't have this feature and thus these can't be used.

Remark 2: If you don't have some of these rails then you'd probably be better of by purchasing the ones I linked to before.

here is an image of a simple jig, It could be used to cut from both the top and bottom of the torsion box to center the V.

well a v shaped router bit should do the job without a jig

Dave,

You're not stepping on anyone's toes here... We're all friends here, right?

I looked at your dxf, and at first blush I liked it. But it would require some alignment stuff that you don't show on your sketch. At the very least, an angle above it all, to keep it from shifting down. Is there an overwhelming reason to develop this, rather than black pipe?

We are still considering all options... after all, that's what open source is... and the final plans could include an option to build with angle or square tube instead of black pipe... depends on what folks here what to see.

Right now I am working on the support of the roller bearings, and inboard adjustment on one side... it's not looking pretty... if anyone has any ideas, please bring them forward....

Mike...



hope im not stepping on anyones toes here

Dave

A router or a trimmer will be needed at the completion og the job as the cutting device, this shouldn't pose a problem if one is needed in construction buy it early.
Is a jig really needed most cheap sets of router bits come with a vee groving bit. I have one HSS about 1" wide. OK not the best quality but if the same method is used on all axis there are ony 6 groves.
Cheers

well a v shaped router bit should do the job without a jig

Of course my sketch is not to scale. Just think of how big a V-bit you would need for a 1.5 to 2 inch tube.

I don't think it needs to be burried in the side, just captured so wouldn't a 1" bit do.

Of course my sketch is not to scale. Just think of how bit a V-bit you would need for a 1.5 -2 inch diameter pipe.


true , i was thinking of 20mm (approx .75") bar ,
but if bigger is required you could do multiple cuts until its the size you need

re the angle iron method two grooves routed for the corners of the angle iron to drop into before bolting would stop any slip

think i found a way to do the alignment , just trying to come up with a sketch of it

will post it when done should be easy enough to make by the looks

true , i was thinking of 20mm (approx .75") bar ,
but if bigger is required you could do multiple cuts until its the size you need

re the angle iron method two grooves routed for the corners of the angle iron to drop into before bolting would stop any slip

think i found a way to do the alignment , just trying to come up with a sketch of it

will post it when done should be easy enough to make by the looks


I actually like that idea, Just route a couple grooves in the side of the torsion box to mount the angle, making the outside to outside a tight fit to the edges of the angle iron. defo a KISS idea.

I was also thinking of the achiestdragon’s angle iron rail on the way home. I like it. Just run two dados down the side of the torsion box for it to lie in. No adjustments needed as it will be a perfect match, and it is already straight. Main problem I saw was that achiestdragon’s drawing is missing the bolt that holds the aluminum angle in place. It seems like this bolt would bonk into the mounting screw(s) for the rail. Have to look at the clearances in cad. I guess the rail could just be attached at the two ends, or …

Steve

ok, sketch of angle method with adjustment , and also tube / bar method and v grove method with adjustment also

not shure if this is a bit over the top but should be strong enough

should be to drawn to scale for, 18mm mdf , maybe too big do not know

i used 4 mounting bolts each end , in light designs think 2 may be enough so aligning should be easy

i have not drawn the bearing holders just the runners

dave

added :-
should note the slotted holes on the end plates show vertical adjustment the end plates thay mount to should have horizontal slotted holes
doing it this way will allow for slight drilling errors also

I was also thinking of the achiestdragon’s angle iron rail on the way home. I like it. Just run two dados down the side of the torsion box for it to lie in. No adjustments needed as it will be a perfect match, and it is already straight. Main problem I saw was that achiestdragon’s drawing is missing the bolt that holds the aluminum angle in place. It seems like this bolt would bonk into the mounting screw(s) for the rail. Have to look at the clearances in cad. I guess the rail could just be attached at the two ends, or …

Steve

no it uses a bolt with a countersunk head ,and unless the rail is very small or the bolt too big it should clear easy

the problem is the bolt on the top of bearing support if the bolts there are too long they would dig in to the side of the MDF , but if the right size bolts are used or longer ones filed down there should not be a problem


dave

Okay, we need someone to look at the angle iron (instead of black pipe) in CAD... Any volunteers?


On an unrelated subject, here's the angle iron imbedded into the gantry for the roller bearings. How many degrees of freedom do we need to consider for alignment on this? We can embed it in the gantry, and hope it works. Or we can add horizontal adjustment. Or we can add horizontal and vertical adjustment. What do you prefer?

Mike...

You guys are making this way too complicated, imo. Routing 2 accurate dadoes down the edge of a box (which itself needs to be VERY accurate) is no picnic.

How much flex does gas pipe have? I read the other day (somewhere around here) that the stiffness of a tube increases by the cube of the diameter. So my 2" conduit is about ~8x stiffer than 1" gas pipe. I have a 5ft piece laying around and I can't feel any flex with a LOT of force on it. It measures 2.1" OD, so a 2-1/8" forstner bit should give a pretty nice fit. A simple drill press fence and stop should give near perfect results. As far as I can tell from my router (as yet unfinished :( ), no adjustment is needed. Provided the torsion box is dead flat.

Mike's going to stop by next week and have a look. Then he can see what I'm talking about.
Not a good picture, but here's a quick look for those who haven't seen it. Just the two endplates holding it in place. Nothing else needed.
http://www.cnczone.com/forums/attachment.php?attachmentid=5793

Okay, we need someone to look at the angle iron (instead of black pipe) in CAD... Any volunteers?


On an unrelated subject, here's the angle iron imbedded into the gantry for the roller bearings. How many degrees of freedom do we need to consider for alignment on this? We can embed it in the gantry, and hope it works. Or we can add horizontal adjustment. Or we can add horizontal and vertical adjustment. What do you prefer?

Mike...

I think that the same method could be used for the other half of guide way the in the torsion box. With a table saw a dado could be cut just like on the gantry. Or using a router with a fence it could also be cut. Make the Y axis alignment in the gantry where it attaches to the gantry uprights. The Xaxis only has to move in a straight line so parallel to the table top. use the table top as a Y axis parallel. Then the only adjustment needed is for squarness. of the yaxis.

I see how those bearings are riding the rail at a 45 deg. ... and they come close to the bolts securing the pipe. not the most desireable ?

what about the top and side support - where the bearing is on top of the pipe and the other thrust bearing is on the side - that way,you have one adjust bolt in the rib on the bottom and one on the side....

what are the pros and cons in that thought ?
( i havent built a torsion box , not even the bearing -angle iron assembly yet .. so ,,, not sure how it rides but the load would seem better supported (with more weight looad on one bearing) --- that criss cross design just seems to have an inherent .. i want to break away from the gantry feel to it ....

Just curious, Mike What did you create that .dxf with? AutoCAD 2002 wouldn't open it. 2006 did, though.

Just curious, Mike What did you create that .dxf with? AutoCAD 2002 wouldn't open it. 2006 did, though.

Gerry,

That .dxf file was created with turbocad 11.1. Of course, by now it's kinda obsolete, the design has progressed way beyond that today...

Once I get the design working on the adjustable skate bearing support I'll have some more dxf files... in the meantime I'll just throw up a .jpg every now and then.

I don't think we can assume that a rigid skate bearing support on both sides is the answer. One side, yes, but the other side needs some kind of adjustment. And if no one comes up with anything better, I'll just have to use what spalm has.

Spalm has a great design, there's no doubt, but can it be improved? That is the question...

How do we improve this? see attachment...

Mike...

Ye gads, that is the part of the design that I am least proud of. Seems so hokey. When I posted it in the linear bearing threads. not one response was logged. I think that is still a record.

That said, by golly, it does work. They can ride up and down on the edges of the pipe and obtain a true level. But maybe use sliding wedges or something more sturdy, at least a better carriage to slide in. Gerry seems to be able to pull his into level by tightening his threaded rod.

Steve

Too complicated routing two dados down the edge of box.

Gerry I love your work, but that was not quite fair. Lets see, seven perfectly placed half rounds per side, 4 perfectly placed end holes, 7x4x2 perfectly placed half lap dados screwed together, struts with bored out holes to reduce weight, and two carefully edge rabited skins that recess into the cross members.

Which sounds more intimidating to a newbie?

All kidding aside, after checking, the angle iron rail seems to negate the use of skate bearings. A much large O.D bearing would be needed. It also makes it hard to do a leveling adjustment.

Mike, IMHO, I think that the top and bottom of the half rounds are too thin. I do not believe that you really need the adjustment screws, and removal would allow you to increase the size of the skin over these for reinforcement.

(I’m in trouble now)
Steve

u guys ever read the book cnc shop bot .. ? in it the guy mountnts the long rails vertically without the complex rib and 3 bolt positioners.. see my sketch

those renderings are beautiful -- i'm not that good and fast with 3d as i am with 2d.

not everybody has a router, and of those that do, not everybody is very good with their router --- if getting those 2 slots into the strip for the groove of the angle is not too bad .. then i that almost seems like one of the hardest parts next to making the batter box .. i mean torsion box.. (sorry its late , im tired ) ...

ok .. of course you're not seeing the 3 or 4 or 5 bolts that support the rest of the length of pipe in the sketch.... ( .dxf )

Guys,
What about just supporting the bottom of the pipe with a step? I'm thinking something along the line of triangle stock, mounted to the side of the torsion box, but put in place after the pipes are levelled. The sloped side should give clearance for the bearings on a pipe measuring 1.5" dia.

It's simple, and if required, the pipe can be nested into it using an epoxy metal like JB Weld.
I've got the parts sitting on the bench, so I can check it out later today after getting some sleep.

HTH

Iain

What if were were to do something like this for the adjustment side?

The plate can float freely inbetween those two pieces of angle, and the adjustment can either be a shim (not shown), or 4 shim adjustment bolts (shown).

There is also the capability for up and down adjustment if needed. Just slot the holes in the angle.

Mike...

Gerry I love your work, but that was not quite fair. Lets see, seven perfectly placed half rounds per side, 4 perfectly placed end holes, 7x4x2 perfectly placed half lap dados screwed together, struts with bored out holes to reduce weight, and two carefully edge rabited skins that recess into the cross members.
Steve

:)

You don't need the half laps to make a good torsion box. And, as was mentioned earlier, you can use either a master template and flush trimming bit to get identical parts, or even a simple fence and stops on a drill press.

I've cut large pieces on edge on a table saw quite often. It's not that easy. You could do it with a handheld router, but like I said before, the box needs to be more accurate.

Mostly a matter of personal preference. I think it's easier my way. :)

[QUOTE=spalm]Ye gads, that is the part of the design that I am least proud of. Seems so hokey. When I posted it in the linear bearing threads. not one response was logged. I think that is still a record.

If it helps Splam, I used your idea on my jgro router. It made all the difference in the world.

Dave

Has anyone considered making the linear bearings out of MDF? Attached below are some CAD models of a LB idea that I came up with using MDF with eccentric bushings. I actually made a prototype using my table saw and drill press and it came out pretty good. The distance from the top surface to the rod was within .003/.004 from one side to the other. It was strong too. I put all 230 lbs of myself standing on one foot and it didn't break. I wish I would have taken some pictures of it before I tore it apart to try something else. Food for thought.

jgro

linear bearings and pipe suport

i sketched this now ok not the best method for mounting the liner bearings but very simple to make
mount the bearing bolts , fit nuts to cover the aria of the shaft that does not want to be bent , using a piece of tube over the nuts bend the bolt untill you get the right angle
also shown is a way to get a v slot without a router

not the best way for the bearing holder but with execption of the tube and nuts /bolts its all mdf

its got to be the silliest way of mounting the bearings anyway imho
worth a laugh

dave

Interesting...

If only you could put a hole in the top plate at 45* and thread in a stud. :confused:

Mike...

its got to be the silliest way of mounting the bearings anyway imho
worth a laugh

dave

Has anyone considered making the linear bearings out of MDF? Attached below are some CAD models of a LB idea that I came up with using MDF with eccentric bushings.jgro

This actually takes care of the split bearing problem on the cheapcnc design. Still need a good way to support the precision ground shaft!

Mike...

This actually takes care of the split bearing problem on the cheapcnc design. Still need a good way to support the precision ground shaft!


What I did on my second machine is attached below. I ran a piece of MDF along the whole length of the rod and held the rod to the MDF with some conduit clamps. I've been using it for about a year now with no problems. Think about it, when you use the square adjustment blocks, what is the first thing that you do when you want to start leveling/squaring thing up? You stick a couple of pieces of MDF that are the same thickness under the rods to hold them up at the same height. Why not leave them there as support?

jgro

I like it. You don't even have to make a v in your support...

Mike...

What I did on my second machine is attached below. I ran a piece of MDF along the whole length of the rod and held the rod to the MDF with some conduit clamps. I've been using it for about a year now with no problems. Think about it, when you use the square adjustment blocks, what is the first thing that you do when you want to start leveling/squaring thing up? You stick a couple of pieces of MDF that are the same thickness under the rods to hold them up at the same height. Why not leave them there as support?

jgro

Wow Everyone,

This is COOL! I have not seen this much brainstorming ever on the zone, at least since I have been here. I really like it.

Now I have read most of the posts but there still coming in faster than I can keep up and be able do my job. So if someone has already covered this then sorry for the repeat.

I really don't think the angle iron or aluminum is the way to go. There is just too much precision involved. I have a large table saw myself and I still would not count on the quality of the grooves for the angle. Also the angle offers almost no added support to the table. I do like the square tube idea this should be very available to most, not sure it will be at every hardware store. With that said I must agree with ger on the conduit idea being the better way to go.

Most of the posts that I have read are trying to make this easier by coming up with other solutions to the rod support. I have looked at mikes adjustment idea but this is unneccesary if all the pieces are cut from one template. any error in the master will be the same in all the pieces, thereby negating the error itself. Don't look at gers machine as a machine look at the structure, break it down into all the identical parts and you will find that there are only a few masters that will need to be made.

Now to the reason I like the square tube. Other than availability, there is only one thing keeping it out of the lead. This is having to cut a perfect 90 degree cut in the master template. If the angle is slightly off this will severly wear the bearings because they will be riding slightly on edge. Without some major planning and precision on the builders part this will be the weak link in the design. With a forstner bit the builder could get a very good fit for the conduit pipe with very little that could go wrong.

Just weighing the pros & cons of each idea. Hope no one took this the wrong way. Not trying to pee on your fire.

Keep up the good work! Looking good.
Jimmy

Most of the posts that I have read are trying to make this easier by coming up with other solutions to the rod support. I have looked at mikes adjustment idea but this is unneccesary if all the pieces are cut from one template. any error in the master will be the same in all the pieces, thereby negating the error itself.

True, but there is still no provision for adjustment in the system. To take out any slop you could JB Weld the pipe into the grooves. And this will probably be an option in the plans. But I am still looking at making the ribs a little taller to reinforce the weak looking area at the bottom of the 2" cutout. I'll have to see how long my tap is. I'm thinking about making it 3/4" instead of 1/2". If you need any more strength than that, you'll have to double the thickness of the ribs.

I'm not hearing any negative feedback on the adjuster plate concept, so I'll plan on that.

I guess it's time to move on to the gantry design. And thoughts or preferences?

Mike...

JGRO, thank you for your stuff. I don’t know whether to love you or hate you for starting me in this obsessive hobby. A couple of comments about the rail with the clamps. This would require a triple bearing truck as you have shown. Fair enough. Can you really reach around and adjust the inside eccentrics? Gerry has turned me into an anti-flex maniac and I see the possibility for a lot of side to side flex. It could be solved with screwing the rail to the support along its length, but how do you repeat this for the medium length axis that is up in the air?

Jimmy, I guess the angle or square channel concept is dead (?), because of mounting. But there are two other problems with it. You can not use the popular angle/skate bearing arraignment with two angles facing each other. They will rub on each other. A bearing with a larger O.D. will solve that, but… The other thing lost is the adjustment concept to obtain level just mentioned by Mike.

Maybe this has been finalized but just wanted to throw it out. Is 2 inch pipe a little large? Or is bigger better? I am sure it is stronger, but how much strength do we need? I used ½ inch which maybe too small, but it seemed strong enough. Gerry used 2 inch and had to drill holes in his torsion supports because he couldn’t lift it. Maybe meet half way, at least for a smaller 2x4 foot design?

Steve

Maybe this has been finalized but just wanted to throw it out. Is 2 inch pipe a little large? Or is bigger better? I am sure it is stronger, but how much strength do we need? I used ½ inch which maybe too small, but it seemed strong enough. Gerry used 2 inch and had to drill holes in his torsion supports because he couldn’t lift it. Maybe meet half way, at least for a smaller 2x4 foot design?
Steve

Hi Steve,

Nothing is finalized yet. I picked the 1 1/2" pipe (1.9" OD) because I have a machine with a solid 3/4" precision ground shaft, and it flexes like crazy. So of course, I am erring on the side of being too rigid.

Now if someone has a spreadsheet that would let me calculate the amount of deflection in any given size pipe, maybe we could downsize. Do we have any spreadsheet guru's here? ;)

Mike...

sorry for yet another pipe support design but .

i quite like this idea
it solves a lot of construction problems in that theres no high tolarance routing to do
as long as you got a nice straight edge on the MDF
also offers simple construction and should be easy to adjust the entire lenth of the bar with only 6 bolts for table alignment

should work with anysize bar with minor changes
think i may use this method myself

dave

Mike, Remember the torsion box is there to support the pipe. Not the other way around. :p

I agree, need to call in some big guns on the math of torsion box / pipe size. How may struts, width/thickness of struts, table size, etc. Complicated stuff but there are some people here at the Zone who know that stuff. Just got to bribe them.

(or we just wing it)
Steve

I am just posting what we have seen. Ger's is 2" so that is what I have been useing as the number. We may be able to get away with less but after comparing the price on the gas pipe vs conduit I believe the thin wall conduit taht ger used is a better bang for the buck. A tiny bit more expensive but very little. Also you have a very consistant finish on the conduit that the gas pipe can't match. Also the larger pipe make bearing clearance easier.

Also nothing is dead! I am just trying to weigh the pros & cons of each idea and share the results with everyone. These are just my views.

This machine can't be all things to all people, but I want to help design the best machine we can for the intermediate beginner. And when I say intermediate I mean someone who wants just a bit more than a small hobby machine. I personally want a machine that can do a days work if I need it but does not cost more than $500-$1000 complete. This should easily be achieved.

Please don't use the price numbers as a set in stone item. This is my budget. Lets continue on the path we have started and closely examine each item carefully. Don't pick it because it is the easiest, pick it because it is the best and easy!

I am enjoying this! Keep the good ideas coming!
Jimmy

Gerry used 2 inch and had to drill holes in his torsion supports because he couldn’t lift it.

Not so. My torsion box is 60" x 32", and it's only supported at the ends.It spans 60" with no sag. :) It was way overbuilt, so I tried to make it a little lighter so it's own weight wasn't working against it. It probably weighs around 40lbs, most of which is from the 1/2" mdf skins (which were the cheapest way to go, not what I really wanted to use).

The only hard part about lifting it is that it's a bit awkward due to the size. ;)

Sorry Gerry, didn’t mean to misstate you. Is the size of the 2" pipe in the “overbuilding” or would you go with it again? What about a 2'X4' size?

What size do people want?

Steve

ok

done a cross sectional view of the bed , think this should be easy to build and provide a ridgid structure ,, its using 20mm bar but i guess that 20mm electrical conduit should do the trick also
may be lighter than some other designs but i'm using 20mm steel angle at 3mm thick for bed supports could use mdf for these i supose

i set the width of the bed to 600mm as mdf from the local hardware store comes in in a 620mm *1200mm size could be scaled easy , may reqire more bracing not shure what do you think

Dave

Gerry,

I have got to ask you, since I brought up the price thing, I hate money it impairs creative thinking, but how much do you think you have invested. I know we are comparing apples to oranges because you went with the baltic goodies. I am trying to keep a bit of an idea of what this thing is going to take. Don't include the electronics, I'd rather not get that started yet.

One more thing I wanted to add is, we all have different areas of expertise. Mine is anylitical thinking. I love word problems, riddles and brain based engineering. :stickpoke I run a cad program in my head. I wish I was as good on autocad but I am not :frown: I tend to picture all of the problem areas instantly in my head. I also tend to be blunt, it's my nature. So don't get offended if I am quick to critique your design idea. I am very open minded so this does not mean your idea is shot down. We are a think tank at the moment, if you think your idea is the best, fix the problem and re-post it. I am loving the free minded feeling of the thread so far. If nothing else we will have a very good batch of ideas for the future builders visiting the zone.

Now last but not least, Mike I really do appreciate you leading the charge on this assault. You are doing a very good job.

I love this thread, thanks CNCAdmin
Jimmy

Dave,

Is there any way to put the bearings on the outside, so you don't loose so much table & cut area?

Jimmy

What size do people want?
Steve

Does this forum have poll capabilities? Maybe a quick poll to find out what size people are looking for. Paul?

Mike...

Now last but not least, Mike I really do appreciate you leading the charge on this assault. You are doing a very good job.
Jimmy

Thanks Jimmy,

It's fun... but there are not enough hours in a day to model up all the ideas that I am seeing here. And I do my fast modeling at work where I am familar with the CAD program, but I really don't have that much time at work. Here at home I am struggling to learn TurboCAD, so it's really slow going. But on the bright side, I can export parasolids and acis files, and jrgo knows how nice that is!

Ever hear the saying, "Teaching teaches the teacher"? Leading the charge, as you call it, does the same thing. I am learning lots! You guys are all wonderful, and chockfull of good ideas! Keep those ideas coming.

Thanks,

Mike...

Dave,

Is there any way to put the bearings on the outside, so you don't loose so much table & cut area?

Jimmy

i did think of doing that , in the end i decided to put them on the inside for a number of reasons

1 it offers better stabilaty , and the carage mounting reduces flex in the sides as there is no presure on the uprights
2 it makes the base lower profile
3 keeps the bearings away form the edge of the table and the tool side of the frame so less crap can get to them
4 it saves having to do routing for the bearing suport angle section
and
5 makes getting to the alignment bolts easier

shame that it makes it a bit wider than the other way around

dave

Is the size of the 2" pipe in the “overbuilding” or would you go with it again?

Steve


I'd use it again. One reason I used it is I have a vertical panel saw I made about 10 years ago using it and rollerblade bearings. The stuff is really stiff, and relatively cheap. Although it costs a lot more now then when I bought it. ~$25 for 10 ft.

Hi Steve,
Now if someone has a spreadsheet that would let me calculate the amount of deflection in any given size pipe, maybe we could downsize. Do we have any spreadsheet guru's here? ;)
Mike...

It's not great but heres a tarted up version of a spreasheet I did to do this a while back...

It's not great but heres a tarted up version of a spreasheet I did to do this a while back...

Very cool Andrew... I like it...

Thanks,

Mike...

Here's one that is not as complete as fyffe555, but I have schedule 40 (standard) pipe sizes filled in. If you want to compare the pipe to a solid bar, use the radius for the wall thickness.

Right on Weatherly...

Looks like .01 deflection before we add the supports... Kwel!

I think we'll use 1" pipe for the gantry. At 30" long that gives us .01 deflection again. We'll use the torsion box for the support, ok Steve?! :p

So far it looks like we have a working area of 36" x 22". Is this a good size for you guys? How about you Jimmy?

Mike...

Hey Guys,

Just got home ate a bite and read over the posts. Thanks for the spreadsheets those were handy. This thing is going to be strong. Don't want to get any hopes up but we may have an aluminum cutter here.

On another subject, This would not fall under the hardware catagory but if you have a steel supplier nearby you cansave some clams on the pipe by going with standard steel tubing. But we still can get the conduit at the hardware so we just have a place where the frugal shopper can save some cash.

Ger $2.50' is not that bad for a very good quality piece of kit (to quote the english among us). Never thought I would be bilingual. I now speak english and american HAHA :p I'm just having too much fun. :D

Holler at me
Jimmy

Railsupport is pretty nice .. u lay the mdf on the angle iron .. the mdf is precut so it is very square to make the holding fixture for the pipe.. then ther is only 1 push down screw from the hole in the rib .. it looks so nice on that 2d drawing , dragonchiester.

that would be cool to get a 3d rendering to bring it to life so we all 'could see the light' of it.

Just reiterating what Steve said. It doesn't matter what the deflection of the pipe is, because the plan is to make it supported, so you won't have ANY deflection.

Also, that Schedule 40 is a lot thicker than the conduit I'm using.

After looking at that speadsheet and seeing "simple mounted ends", here's anm idea that's going to go against everything we've been talking about. :)

If you want to build something easier, try this. Use 2" conduit. You'll possibly need a circle cutter for a drill press. Adjust it to cut a hole with a very snug fit on the conduit. Make a jig to pattern route the 2 holes for an end support plate. Once the first one is made, use it to make 3 more identical ones. Use 2 at each end, about 6" apart. This will greatly increase the stiffness of an already rigid tube. With about a 36-42" span, the deflection would probably not be noticeable with a 100lb load on 2 tubes. No support needed. I personally wouldn't use this, as my goal was zero deflection. But compared to the JGRO type designs, a big improvement. Just keep in mind that this takes up a pretty big footprint, which goes back to Mike's question - what size does everyone want?

Railsupport is pretty nice .. u lay the mdf on the angle iron .. the mdf is precut so it is very square to make the holding fixture for the pipe.. then ther is only 1 push down screw from the hole in the rib .. it looks so nice on that 2d drawing , dragonchiester.

that would be cool to get a 3d rendering to bring it to life so we all 'could see the light' of it.

i could do a 3d view , but takes me a long time to do them ,
and do not have the time at the moment , not tried 3d with my current cad program (totalcad)
im currently in the process of redrawing it adjusting the size so i the pieces can be cut from "standard ?" size sheets of mdf with minimal waste

seems that 1220mm by 607mm is a standard size ?? well B&Q seem to think so and sell it in that size ,need to check homebase see if there sheets are the same size also

what ever happened to 8'*4' ( 2353mm * 1176mm )

Dave

4x8 MDF is 49" x 97", or 1244mm x 2464mm. It looks like they're cutting it into quarters for you. :)

Everything is going metric....even the thickness is in metric....

. Just keep in mind that this takes up a pretty big footprint, which goes back to Mike's question - what size does everyone want?

Ah yes, the footprint... It's looking to be roughly 48"x30", to get a working area of 36"x22". Is this acceptable? Too big? What do you think?

or 1220x762 footprint and 914x558 working area, in mm!

Mike...

Mike,

Can we bump it up just a little to get a full 2'x3'. I am planning on rough carving signs with mine, so this will be a more convenient size for me.

Thanks
Jimmy

If the design uses supported guides, whether round or square tube, or even angle, It shouldn't be a problem to scale it up a little more.

Hey Guys,

The reason for the last post was foe the plans stage 24"x36" is a standard size in the sign industry so this would make it easier to get blanks if some one chose to do a sign for another person. I personally could probably build the machine from the discussion notes.

Are there any metric sign people here reading. If so what would be an equivelant metric standard size, so we don't run into problems with being 1 or 2 cm too small. I would hate for someone to have to scale up a perfectly good set of plans for a couple of inches.

Let us know
Jimmy

Sure it's easy enough to give you two more working inches...

You can either make the y beaing shuttle 2" smaller, from 8" to 6", or you could make the y pipe (gantry pipe) 2" longer.

I had hoped to keep the pipe an even length, in this case 5', cut in half! But since we still need a little extra length for the gantry wall and the adjustment blocks, we could just go right to 3' pipe, and keep whatever extra we gain on the y axis.

Mike...

If I had to cut material that was 24" x 36", I'd make sure I had 2" or more extra travel on all sides. You may have to get the tool to the outside of the part. And it's nice to be able to have the tool enter the work from outside as opposed to plunging down. This is important if using offsets (G41/G42) which need lead in moves.

Also, the farther apart your bearings are spread, the stiffer the machine becomes. I'd increase the pipe length as opposed to bringing the bearings closer together.

Mike,

I agree with you and Ger. Lets figur on 3' for the y pipes. I really would like to be able to do full 24"x36". Hope thats ok with every one. Let us know if it isn't.

Thanks again
Jimmy

I'm not sure 3' for the Y pipes will be enough to get you 24" of travel plus a little extra for good measure.

Consider that just mounting the pipes in your gantry sides you will lose 1.5", assuming that at a minimum your gantry is 3/4" thick on each side and the pipes don't protrude through.

Your 36" pipes have turned in to 34.5" pipes

Then, you take Ger's suggestion of having 2 inches on each side for working around the edges of you part and allowing for lead-ins and read-outs

Your 34.5" pipes are now 30.5" pipes

Add in some gaps of 1/4" on each end for safe limits and now you have 30" pipes

This leaves you with 4 inches of space for the width of your z-axis. Seems a little narrow to me considering the sturdy engineering you guys are putting into the rest of the machine.

A few more inches would make all the difference in the world.

This thing is getting wide quick... Lets work backwards...

Let's allow 1" around for working, so we are at 26" of pipe.

Then allow 8" for the bearing shuttle, so we are at 34" of pipe.

Allow a double wide gantry wall plus an adjusting block, that's 2 1/4" on each side or 4 1/2", so we are at 38 1/2" of pipe.

That's a big footprint to get 24" of quality machining in the y direction. Is this what you want to see on the plans?

Mike...

P.S. I don't own a bench that wide!

Mvaughn,

Yes I caught that after I posted and started thinking about it. I will have to depend on Mike or one of the other cad guys to figure the correct length of the pipes.

Ger,

Do you know what would be the least we could get by with on the lead in space. I don't want to go crazy on the floor space. I believe this will help the great gents in the cad dept. :)

Happy trails,
Jimmy

Howdy,

Mike I believe you and I will both have a bench that wide soon. If we use Ger's as a model even with 22" we will be almost 38" just figuring on scratch paper. I believe the achilles heal has been found. I think though most will live with the loss of shop space for the quality of the machine we are designing. I'm already clearing out a space for mine. HAHAHA

Any Solutions, I want my cake and a fork?
Jimmy

You can get by with just over the tool diameter, but programming will be more difficult because you have to be real careful where you drop that tool.

You also should have some extra room if you use limit switches. You don't want to be always working right next to limit switches.

When you start worrying about 4", what's the point. Just make it bigger. :) It was no longer a benchtop machine as soon as you passed 24".

BTW, mine has a Y travel of about 32". You "could" make this all useable, but I'll probably never cut within 2" of the edges. When all is said and done, it'll be about 44" wide, plus the stepper sticking out the side.

hmm if the design is going to be scaleable is the exact size important at this stage

ok so guess the same design could be converted to cope with metric or impeial sized materials ,

btw latest dimentions for the bed here get it to be 1136mm long 950mm wide for a 900*500mm cutting aria ( 44"L,37"W for 35"L 19"W cutting aria)

suppose it would be better to give the size in the following way
required cutting lenth + 236mm (10")
required cutting width + 450mm (18")

for the rail outside the bearing design

only reason im currently sticking to that is i have already have the rails cut
2*1100mm 2*700mm and 2*300mm ,

dave

ps , i should add that i do know that the actual cutting aria of my machine is going to be smaller than stated above ,
but untill built im not shure exactly how much ,looks like 56mm at the moment (2 bits of mdf )
but i only intend using it on 300*600mm matierial so it has not been my biggest concern anything above that is a bonus to me

I only had a few mintues today to play with the design... that rush job had to come first!

I quickly threw the gantry together, only to realize that it's a little tight inside that torsion box. I might have to open it up so we can get at that adjust screw in the center.

Do you have any thoughts on this? Oh, btw, the pipe is 39 3/4" long!

Mike...

While you always see everyone using 4 pipe adjustment blocks (1 @ each end of each pipe), you technically only need 1 to align the pipes parallel to each other. Fabrication skill may need to be higher, though.

Mike, for the torsion box to function properly, both skins need to be glued permanently. You can't have access to the inside. It's the skins that give it the strength, not so much the inside framework.

Mike, for the torsion box to function properly, both skins need to be glued permanently. You can't have access to the inside. It's the skins that give it the strength, not so much the inside framework.


Well that makes it hard to get the the adjustment bolt now doesn't it. :D

Personally, I think that it's way too complicated with all those adjustment bolts. Like others have said and Spalm proved (Ger used a CNC) it is possible to accurately cut the recesses in the torsion box so you don't need the adjusters.

While you always see everyone using 4 pipe adjustment blocks (1 @ each end of each pipe), you technically only need 1 to align the pipes parallel to each other. Fabrication skill may need to be higher, though.

well thought the use of 4 would allow the pipe to be adjusted at ether end

1 yes better if the drilling is out is off
and 2 so it may be aligned with the bed
if one end of each is fixed and the table not quite level then its going to be hard to correct and would be corrected by having them adjustable anyway

i would only say 1 per axis should be fixed to alow for correcting skew with the bed and so may as well make all 4 adjustable ,


currently working on the next axis , hmm y or z next , and if y then do i mount the rails side by side or above each other , z next could be an interesting thought ? driving it may be a problem

dave

Well that makes it hard to get the the adjustment bolt now doesn't it. :D

Personally, I think that it's way too complicated with all those adjustment bolts. Like others have said and Spalm proved (Ger used a CNC) it is possible to accurately cut the recesses in the torsion box so you don't need the adjusters.

That is why offered a jig and a V desgn, It can be machined with a router and a jig after assembly of the torsion box. then the use a square tubing would make perfect sense.

Well here goes guys, be prepared to read :D .

I will go ahead and write the portion of the assembly manual, that concerns the assembly of the gantry torsion box. Maybe this will explain why this is such an easy to build design even without the supports having adjustments.

Step 1. Cut master template for the gantry rail support found in figure blah blah. after satisfied with the fit to the rail itself, go to step two.

Step 2. Pre-cut x number of pieces for the rail supports. Cut them about 1/16-1/8"oversize.

Step 3. Drive two screws or nails, which ever is your peference, one at each end. These will asist in holding the pattern firmly in place and centered on the rail support blank.

Step 4. Using a router or quality laminate trimmer, with a pattern or flush trim bit, proceed to make all of the blanks perfectly match your master template.

Step 5. Following the information provided in the plan set. Cut the gantry sides. If accurate enough equipment is available, you can cut them seperately. If not use the same method outlined in steps 1-4. It is very important that all like pieces be Identical dimensions. Once all gantry side pieces are cut correctly go to step 6

Step 6. This is where it gets a bit tedious. Hang in there we will get through it. Stack the gantry side pieces exactly as they will be on the machine. Make absolutely sure that all pieces are aligned flush, square and true to each other. Clamp firmly together. Follow the plans directions for the exact location for the master template made in step 1. Once the position is found, carefully align the piece on the gantry side, then attach using the same method you used in making the rail supports. If you have followed the instructions carefully to this point the first major hurdle is past.

Step 7. Using the same forstner bit you used to make the master template for the rail support, in a drill press, put the bit against the template firmly and drill your hole. Be very careful not to let the bit wander. If you have been diligent in your measuring the pipes should be perfectly supported and absolutely parralel.

Step 8. This is where your measurments are used. Depending on how wide you have made the gantry, all that is left to do is to cut the filler pieces that fill in between the rail supports and attach the skins to the torsion box. A word of caution be sure the torsion frame is perfectly square and true before gluing and screwing it together.

I really hope this clears up the doubt in peoples minds about the ease with which precision parts can be mass produced. Worse case senario is you mess up a few pieces making the master templates but once it is perfect every one of those pieces will perfectly match the last one. I use this method alot in making custom fiberglass speaker enclosures. It makes a mess when cutting mdf this way. Your shop will look like a dust storm hit but it is relatively fast and the most precise way I know of making alot of the same part.

Let me know what you think,
Jimmy

Hey, just some random things.

Just stopped by Home Depot and got prices for pipe. This is not the biggest design cost at all, but I thought I’d document it anyway. Prices are 10 foot lengths. Size is inside diameter.

EMT
2” = $20
1½ “= $16.50
1 ¼”= $13.50
1” = $8.50

Black Gas Pipe
2” = $28
1 ½” = $22
1 ¼”= $18
1” = $13

It’s getting large! Let the design be adjustable in size. Maybe draw it smaller and then a builder can just add a documented offset in either or both axis to grow it. Identify these offsets in the drawings. Don’t scare away the newbie. (Just a thought)

The boxes need skins on both sides, and the pipes don’t need adjusters. If you really blow it and cut something too short, you can always add a shim. These should all be cut at one time with some kind of jig, so I promise they will all be the same. The bearing adjustment thingy will allow you to obtain level for X/Y and vertical for Y/Z.

I am still a believer that the box supports the pipe, and the pipe just lays in the trenches. It does not look like the box is attached to the gantry walls.

I am in enough trouble, so I will leave the double thickness gantry wall for another day.

Steve

Howdy again,

Are you tired of reading yet? :mad:

Just one thing that I wanted to say. We have tentativly decided on 2" conduit(this may change depending on the design work) and I am not sure if 2" is the precise the OD of the conduit so I thought I would make it a little easier to get the correct size hole for the templates. My local hardware stocks an adjustible circle cutter. It makes it easy to get a very precise hole any size inch or mm. If your local hardware does not carry them www.harborfreight.com or ebay do most of the time. I have seen them fo $6-20 depending on where and the size you order. You will wonder how you lived without it.

Live long and prosper,
Jimmy

thought the following would be suitable for what im trying to do

get wood cutting list
call at wood suppier ask for bits of MDF in the sizes needed

get bits home

cut them where needed ( non critical cuts required so 10deg of is only going to make it look rough)

drill out as marked ( 2 to 3mm with in the required positions anyway )

elongate any holes that don't quite match file or reammer normaly does the trick

screw together and assemble

the only real critical bit of drilling is making the bearing holders so far
and even those can be elongated a bit to get them right

sorry but even i would have difficulty doing the other design ,
and i will admit my wood work is bad
its the main reason i need a cnc :)



dave

Steve,

The more I think about it the more I agree on the size thing. This thing is becoming a MONSTER. Although that would be a good name for it "THE MONSTER ROUTER" (if we could only make it growl at you when you cut it on) sorry a bit of daydream typing there :o . But seriously lets back up and make the cutting area about the same size as the jgro machine. It should have a bit smaller foot print than the jgro since we are mounting the bearings to the outside. This also seems to be a popular size. Who knows if enough requests come in we may offer a larger plan beafing it up where needed.

May the swartz be with you,
Jimmy

Steve,

The more I think about it the more I agree on the size thing. This thing is becoming a MONSTER. Although that would be a good name for it "THE MONSTER ROUTER" (if we could only make it growl at you when you cut it on) sorry a bit of daydream typing there :o . But seriously lets back up and make the cutting area about the same size as the jgro machine. It should have a bit smaller foot print than the jgro since we are mounting the bearings to the outside. This also seems to be a popular size. Who knows if enough requests come in we may offer a larger plan beafing it up where needed.

May the swartz be with you,
Jimmy

may be better thinking about what sort of cutting tool the machine is going to use then ,
because from this you should be able to work out the load that the tool is capable of

theres no point having a machine that could would withsand grinding granite blocks at 200ipm if your using a demill to cut with

Achiestdragon,

Grinding granite at 200 in/p min would be cool! Do you think we could build it on a budget :stickpoke .

Seriously, I would think nothing bigger than a good laminate router or maybe a 1 horse router. No dremil machine here. I believe 1.5" conduit would be bordering on overkill which is just right for me. I would still like to see this machine capable of cutting aluminum. This way it makes the perfect stepping up machine. The jgro machine, from what I can tell is wheezing and twitching when it even looks at aluminum. Not meaning to insult the machine, it was not designed for that. I want the builder of this machine to be able to cut aluminum in several passes easily. Does every one think this is possible. I am still going to build "THE MONSTER ROUTER"(it just has a ring to it). so this size does not help me. But as we stated in the begining this machine can be scaled almost as big or small as you wish. We still have to do the engineering to determine the scaling points. Example: If you are going to make it 12-20" wide you will need to make the x axis pipe___ big. The torsion box will need to be____thick and so on. This will allow us to design the basic structure open source then release a set of plans a set size with a sheet telling you what to do to increase or decrease the size. Fairly simple stuff to knock together.

The only reason I am suggesting changing the size is that the machine is much to big to be called an entry level machine. Also I don't want to waste the cad designers time working on something that most don't have room for yet. That is the beauty of the jgro machine. It is small and very functional but it severly lacks the strength and accuracy to do a hard days work IMHO.

Jimmy

Achiestdragon,

Grinding granite at 200 in/p min would be cool! Do you think we could build it on a budget :stickpoke .

Seriously, I would think nothing bigger than a good laminate router or maybe a 1 horse router. No dremil machine here. I believe 1.5" conduit would be bordering on overkill which is just right for me. I would still like to see this machine capable of cutting aluminum. This way it makes the perfect stepping up machine. The jgro machine, from what I can tell is wheezing and twitching when it even looks at aluminum. Not meaning to insult the machine, it was not designed for that. I want the builder of this machine to be able to cut aluminum in several passes easily. Does every one think this is possible. I am still going to build "THE MONSTER ROUTER"(it just has a ring to it). so this size does not help me. But as we stated in the begining this machine can be scaled almost as big or small as you wish. We still have to do the engineering to determine the scaling points. Example: If you are going to make it 12-20" wide you will need to make the x axis pipe___ big. The torsion box will need to be____thick and so on. This will allow us to design the basic structure open source then release a set of plans a set size with a sheet telling you what to do to increase or decrease the size. Fairly simple stuff to knock together.

The only reason I am suggesting changing the size is that the machine is much to big to be called an entry level machine. Also I don't want to waste the cad designers time working on something that most don't have room for yet. That is the beauty of the jgro machine. It is small and very functional but it severly lacks the strength and accuracy to do a hard days work IMHO.

Jimmy

ok kool

as to cad well i can do 2d but limited on 3d , i wouldent normaly start doing a 3d image untill i got the plans finalized , although there good for showing ideas

im thinking out my z axis at the moment , i got a way of doing the y using the bars in a side by side arrangement with the tool in the middle , just seeing if i can get the z axis construction easy also ,

but if i decide to use this method im going to reduce the cutting aria to 400*600mm about 16"*24" as i think the machine would be too big , i was trying to get as much aria as possible but i need to be albe to move the thing ,
so i didnt originaly want to since i already got some stainless steel bar for the runners to the lenths needed

going to cut about 250mm from the x axis lenth and see how much of the 700mm lenth's is going to be lost in the mountings for y/z

although may change the y/z axis method yet

i would think having the y axis rails spaced ether side of the tool would provide better stability than one above the other with the tool offsett from them

im thinking of how to best mount the z axis on the x carrage , so the y rails move in the z axis , if that makes sense , it seems easyer than having to mount the z axis rails and motor between the y axis rails if the y rails are positioned horizontaly to each other

still not knowing if this is going to be a good idea or not , will spend a day or so thinking of diferent ways to achive this , pick the best , have another think , see what it looks like , see if i can improve it , if it looks worse than the more conventional design of one above the other will revert back

still got a week before im going to be be ready for the mdf here

dave

Step 6. This is where it gets a bit tedious. Hang in there we will get through it. Stack the gantry side pieces exactly as they will be on the machine. Make absolutely sure that all pieces are aligned flush, square and true to each other. Clamp firmly together. Follow the plans directions for the exact location for the master template made in step 1. Once the position is found, carefully align the piece on the gantry side, then attach using the same method you used in making the rail supports. If you have followed the instructions carefully to this point the first major hurdle is past.

Step 7. Using the same forstner bit you used to make the master template for the rail support, in a drill press, put the bit against the template firmly and drill your hole. Be very careful not to let the bit wander. If you have been diligent in your measuring the pipes should be perfectly supported and absolutely parralel.



One of the reasons I used the 2" conduit, is because it gives you more room to work with. You can support a good amount of it, and still have plenty of room for the bearings and associated hardware to ride on them without worrying about clearance issues.

As Steve mentioned, dimensions are ID. So Jimmy, most likely a forstner bit will not be a good fit. Si I'd recommend a circle cutter like this http://www.woodcraft.com/family.aspx?familyid=799 to cut your template holes. But here's an easier way to line everything up. I'll attach a drawing of my gantry side for an example.

1) Start with a SQUARE (important, at least one corner anyway) blank of MDF. Using a drill press with circle cutter, and a clamped on fence, cut/drill the two holes for your pipe. In my drawing the 2 red holes are the ones I'm talking about. The others are decorative/ lightening holes. The distance between them is not critical. The fence will keep them in perfect alignment. The bottom edge must be perpendicular to the edge against the fence. Once the holes are drilled, the bottom edge is used with either a table saw or router table to cut/route grooves to align the bearing carriages. This will insure that your gantry is perfectly vertical, with no adjustment needed.

If you don't have a table saw or drill press, a handheld router and straitedge (and creful and accurate layout) can give you similar results.

2) Now that we have our sides (we'll use 1 as a template and flush trim the second to match), we can use them to make the torsion box parts. Notice the smaller blue box between the red circles. These will be our vertical pipe holders/ torsion box parts. Use a spacer off the same edge you used against the fence on the drill press, and screw the blank to your side. Use a flush trimming router bit to trim the ends to match the holes in the gantry sides. Remove this part and use it as a template to flush trim as many as you need.

If this sounds complicated, it's not. And this will give you a gantry with NO adjustability needed. Build the box, place the bottom pipe between the gantry sides, set the box on the pipe, and slide the top pipe through. Everything tight and in perfect alignment.

Basically the same thing Jimmy said, but in the opposite order.

Thanks Ger,

I sat here for about twenty minutes while typing that trying to go exactly the direction you did but could not word it to were the reader would understand. So I went torsion box first. You worded that very well. Maybe the fog is lifting from in front of this idea.

What do you think about changing it to about 1/2 the current design size? Should we stay with bigger or go a bit smaller. You have been here alot longer than me. I just want to give the best planned size that we can so we don't cause the majority of the builders to have to scale the plan up or down. If you say down what would be a good size for a universal machine.

One more thing: I mentioned making it about the size of the jgro machine. What is the usable cut area for that machine. I may not have cut it down much from the designed size. I was thinking that it was a good bit smaller than 2'x3' but I don't have the plans here at the shop to be sure. If I made a confusing blunder sorry. My ignorance sometimes baffles even me.

Thanks guys, I might just go on to bed
Talk to you later :cheers:
Jimmy

Gerry, you are one clever guy.

I see that you quietly placed the Y motor on top. Looks like a good move.

I also see that you have trimmed down the gantry walls. After all those previous talks we had about gantry wall flex, I assume you have something in mind. Care to share?

Just a thought. I bet by the time we are done we could come up with a “universal pattern” made out of ¼” ply that someone could crank out on their CNC and sell for a small profit that would handle all of the critical hole cutting. This would include pipe holes, Nema motor holes, and Z pipes, etc. All a builder would need would be a router with a pattern bit or flush trim bit. Remember there are a lot of guys who don’t really want to build a machine, but rather use a machine to build airplane parts, etc.

Steve

Two thoughts here...

working area: jrgo's machine has a working area of 34"x15.5" roughly. You guys seem to like the small footprint of that machine, so should we target something similar? At least it'll fit on our existing benches.

adjustability: There seems to be two directions of thought... one group likes the adjustment. You can drill the 2" holes somewhat imprecisely, and use the screws to get perfect alignment.

The other group seems to think that is too much effort and too much hardware. That group likes gerry's perfectly aligned machine with no adjustment.

Should we do a basic design, with the option of leaving the screws off? Leaving the screws off requires a template or a jig, such as we've already discussed. The hole could be perfectly sized for the pipe, or slightly oversized, with room for JB Weld.

Mike...

I also see that you have trimmed down the gantry walls. After all those previous talks we had about gantry wall flex, I assume you have something in mind. Care to share?

Just a thought. I bet by the time we are done we could come up with a “universal pattern” made out of ¼” ply that someone could crank out on their CNC and sell for a small profit that would handle all of the critical hole cutting. This would include pipe holes, Nema motor holes, and Z pipes, etc. All a builder would need would be a router with a pattern bit or flush trim bit. Remember there are a lot of guys who don’t really want to build a machine, but rather use a machine to build airplane parts, etc.

Steve

My gantry sides are 2 pieces of 1/2" lightweight MDF, with 5/8" thick x 3/4" hardwood in between, mostly around the edges, and at the cutouts. There is also a 3/4" x 3/4" aluminum square tube epoxied in between. It's set in a shallow dado on each piece to align them. My gantry box is about 12" tall, so that alone won't allow the top part to flex, and will help to dtiffen up the whole thing. They are over 30" tall, though. :)

If someone could make and sell a set of templates, that would make fabricating the hole thing a lot easier. All you'd need is maybe a jigsaw to rough cut the parts, and a router to finish them up. That's how I made my gantry sides. I CNC'd a template at work, and made them at home with a jigsaw and router (table).

What do you think about changing it to about 1/2 the current design size? Should we stay with bigger or go a bit smaller. You have been here alot longer than me. I just want to give the best planned size that we can so we don't cause the majority of the builders to have to scale the plan up or down. If you say down what would be a good size for a universal machine.


I'd say have 2 sizes. A 24 x 36, and a 12-18 x 24. They would be practically identical, so any additional CAD work would be minimal.

Gerry, do you happen to know the OD and ID of your conduit? A random thought occured that a heavy gantry with just a few bearings might be enough point load to distort the tube, so wasting all the efforts in aligning the tubes during the build. So the heavier the gantry the more bearings needed to avoid wearing flat tracks in the tube.

Also are you intending to have the gantry free riding on the top of the tube or lock it in the vertical with bearings under the tube as well?

My first machine is an MDF 1' x 1' with 1.5" drill rod/skate bearings on the X, with the gantry riding on the top ( with 2x45%) only. After a few years infrequent use its worn flats on the drill rod needing regular realignment. Also since its top mounted only , if you really speed it up the leadscrew whip or the cutting force lifts the gantry off the rail.

Andrew

The OD is 2.1". That's measured with a caliper, and it's very consistent. I don't think the tube can be distorted by the bearing load.

Look at the first picure in my thread, you'll see the tubes both top and bottom, with the bearings held tight with threaded rods. http://www.cnczone.com/forums/showthread.php?t=1356&page=1

I have a panel saw using the same conduit and bearings that I've had about 10 years. It doesn't get used often, but there is absolutely no wear at all. There isn't as much pressure on the bearings, though.

I just did a quick search and found that galvanizing is usually much harder than than the steel, so this might be a factor.

Gerry,

“that would make fabricating the hole thing a lot easier” (nice pun :D )

So the drawing that you supplied is not the real gantry wall? (I realize that it may just be conceptual) but I don’t get it. How does that drawing tie into the stiffened gantry wall that you described? Seems you mentioned having threaded rod through the pipes to tie the gantry together. (?)

Did you really plan to send just threaded rod under the table to tie the two gantry walls together, without any other box or support or adjustment? It seems like it really worked for the Y/Z carriage (which I was too chicken to try, and am really starting to like with the leadscrew on top), but in this case at least you can have threaded rod on each side of the Y box and two plates that can “tilt” to obtain level.

So to summarize as I see it. I was trying to build a strong 4 sided gantry and a strong 4 sided carriage that would then be adjusted to the pipe. You have a 2 or 3 sided structure that uses threaded rod to pull into the pipe. Yours does seem more elegant, as long as the top and bottom plate for the Y carriage and the gantry walls are really stiff. If this is true, it seems like the Y torsion box should be just a little bit short and not attached to the gantry walls to allow the tilt thing for adjustment.

As fyffe noted, I also have noticed flat tracks on my pipe after limited used. The bearing tension here is tight. But I am willing to deal with it by rotating the pipe every so often as this design style has so much else going for it.

Steve

“that would make fabricating the hole thing a lot easier” (nice pun :D )
unintended :)


So the drawing that you supplied is not the real gantry wall? (I realize that it may just be conceptual) but I don’t get it. How does that drawing tie into the stiffened gantry wall that you described? Seems you mentioned having threaded rod through the pipes to tie the gantry together. (?)

That's it. Here's a picture of one and the template I used to route it. (It's not finished yet) Each side consists of 2 1/2" mdf sides, assembled semi-torsion box style. :) You can see the hardwood between the pieces. If you look closely to the template pic, the pencil lines running vertically is where the aluminum tube is located.


Did you really plan to send just threaded rod under the table to tie the two gantry walls together, without any other box or support or adjustment? It seems like it really worked for the Y/Z carriage (which I was too chicken to try, and am really starting to like with the leadscrew on top), but in this case at least you can have threaded rod on each side of the Y box and two plates that can “tilt” to obtain level.

There is a design flaw in the Z-axis carriage assembly. The threaded rod doesn't keep the top and bottom aligned. The way it is in the picture, the top and bottom could move independantly. The fix I have planned is to run a panel behind the gantry box tying the two together. Had I known ahead of time, I would have left a bit more room for it, as it's a little tight. :)

As you probably know, making the gantry box the correct length and mounting your bearings in just the right place relative to the pipes is pretty much impossible. With this in mind, I made the gantry box a little on the small side to allow for some adjustment. I plan on making a shim the correct thickness once I know what it is. (Or multiple shims for possible angular adjustments) No threaded rod through the pipes, the sides will just be screwed into the box. Since the pipes will fit into the sides, no adjusment is necessary.

There will be 2 threaded rods just below the bearings pulling the 2 sides together under the table. The gantry box will keep the sides parallel, with no way to twist. If I find that the pressure from the threaded rods bow the sides (too much, a little will probably be OK) I'll add some steel or 1/4" aluminum angle across the bowed areas to keep them flat. I don't think I'll need this, though.

There are no provisions for leveling the gantry box, because the 2 sides will be identical. If I do end up needing some adjusment, I can put some in the bearing carriages.

If the pipes do wear, it should be a simple matter of loosening the 4 nuts on top and giving pipes a little turn. Same for the X axis.

Thanks pictures, I'm one of those visual types.

Phil

well been busy , came up with a couple of design ideas but after some thought i am considering on a different approach :)



anyway been toying with this little concept also
with the current design your using think you may like it also

the big problem i think with using your current y/z axis design is the increased bed space needed as the tool is offset from the center of the x axis slides

although this may not be that the tool can position off the end of the table using your current plans this addidtion to the end of the bed may provide usefull for doing work on the ends of matereals like dovetail joints or drilling the sides etc

and ok rather than reducing the bed lenth it takes advantage of what is lost with the tool offset (not shure how much offset you got to play with)

sorry if the drawings a bit rough , means the end of the machine would have to be at the edge of the bench ,and so would need to have a method to stop it falling off
but the addition would enhance the capabilaty of what can be done with it and i guess for people working with wood or aluminium maybe it would be verry usefull if enough bracing is used and the faces lined with a suitable material it should not be a problem

i like the idea so may be worth the time to perfect it

Dave

ger you mentioned someone makeing a set of templets and sell them.. thats a great idea..but I was wondering if we can setup something like pfranc and the garmin cables. the idea was to create a cable end that can be used on garmin gps's easy to mold and sell them for what others would pay some might pay 5 bucks others would pay 40 anyway check out http://www.pfranc.com/

Well, I've had company all weekend, so I haven't been able to play much. This afternoon I started on the first torsion box. Let me tell you, torsion boxes take time. And without a mill to cut the ribs, there's no way I can build a precision torsion box.

Well OK Ger, I didn't use any templates or anything. I laid out each rib using a tape measure, and cut it using a table saw and a drill press. I drilled and tapped the alignment holes with a hand held drill motor.

I'm off to the hardware store in a few minutes to get a couple pieces of pipe and some bolts. I'll let you know what I come up with...

Mike...

I'm back home. I've got the black pipe and nuts & bolts. I've assembled the pipe in one side of the torsion box. And to think I was concerned there wouldn't be enough adjustment. geesh... There is sooooo much adjustment... :D

Before I can go any further, I have to build the legs, and the gantry. But like Jimmy said, "I'm liking this!"

Mike...

And without a mill to cut the ribs, there's no way I can build a precision torsion box.


Sure you can. I'll show you when you come by. :) Table saw and drill press are all you need.

ger you mentioned someone makeing a set of templets and sell them.. thats a great idea..but I was wondering if we can setup something like pfranc and the garmin cables.

I'm sure that when a set of plans get finalised, ther will be at least a few people here willing to make templates (or even parts) for others. But since we're not talking about $.50 worth of plastic, I'm not sure that pfranc system would go over too well. :)

Mike, is your plan to adjust all your bolts, and then put the skins on? What hapens if the bolts come loose, and you can't adjust them. Do you put some access holes to get at them?

Mike, is your plan to adjust all your bolts, and then put the skins on? What hapens if the bolts come loose, and you can't adjust them. Do you put some access holes to get at them?

Yes, the plan is to put access holes in the lower skin!

Mike...

Hello Everyone,

Good to be back on the zone! Had a long weekend of cleanup around the house.

I see we have a builder, this is very good. If my company can cough up a little dough, I am hoping to be building mine soon :)

I would like to see if the concensus is to do a large and small plan or stay with the big plan. My vote is to do large and small because all the designers will have to do is adjust dimensions for pipe size and leadscrew sizes. So I really don't see a problem with this. My opinion though. :)

Let us know what you want.
Jimmy Southern

I see building going on, but I didn't see any plans of a complete machine. Did I miss them somewhere. :idea:

I'm hoping that this thread stays on track and results in some plans that the uninitiated can follow.

Keep up the good work guys. I like your ideas and motivation.

No, you didn't miss any plans... I'm still developing the design... I'm still looking for a CAD solid modeler who could help me too!

I had no time this weekend due to company...

And I'll no time this evening or tomorrow evening cause I am buying a new car. But after that I hope to get back to the development.

Regarding the building you see going on in my basement, I am just trying to validate a couple basic concepts before I continue drawing up the plans.

Plus, I want to get over to Gerry's place and see what he's got going on. Gerry, I hope you have a template and a jig handy, so I can see how you can make a precision torsion box. Remember, a precision torsion box is going to be an option on the drawing.

Mike...

OK, maybe we should leave construction techniques and get back to design. I applaud you Mike, nothing like trying something in the shop to see how it will really work.

It looks like this thread is headed for a torsion box X and Y beam with 2” pipes with angle bearings (and rod for Z?). There are a few remaining open things in my mind (and a hundred details). The big ones IMHO are what the carriage will look like and how to get the bearings tight (or adjusted or whatever you want to call it).

We seem to be basing this off of Gerry’s machine and to quote:
“There is a design flaw in the Z-axis carriage assembly. The threaded rod doesn't keep the top and bottom aligned. The way it is in the picture, the top and bottom could move independently. The fix I have planned is to run a panel behind the gantry box tying the two together. Had I known ahead of time, I would have left a bit more room for it, as it's a little tight.”

I am assuming this is a front to back tilt? Not side to side or twist?

This is what I had pictured so I had used side plates with an oblong hole for the box to solve this problem. The disadvantages are loss of an inch or so of Y, they make the carriage look like a bird house, and I had to add additional bearing adjustment. Gerry’s two panel version is really elegant in that the threaded rod can be tightened to obtain tight bearings. But it seems like a back panel must therefore be somewhat floating to allow this adjustment. The main load is in the front, which wants to tilt the carriage forward, so it seems like this panel would be pulling apart, negating its use. The best outcome would be that someone would tell me I am crazy.

Just to show how my mind jumps around; I have been playing with my small pipe prototype this weekend and noticed that my main flex problem is in the right side of the gantry. My leadscrew is temporally attached to the left gantry wall. I can move the right side back and forth about ¼”. I don’t know where this is coming from. The lead screw keeps the left side solid. Maybe the larger pipe and bearing spread will reduce this. Moving the leadscrew to the middle as Mvaughn had warned me about should reduce it by half, but I bet that the left side will then move a bit also (dual leadscrews would kill it). This makes me wonder about the Y leadscrew on top of the carriage instead of the center back.

We need more brainstorming.
I need to prototype some large pipe boxes,
Steve

Well I had a few minutes this morning, so I tweaked the gantry a little bit. I spread the bars apart, and reduced the number of ribs. That looks a bit better.

That's 1" pipe, btw, with a 1.315 OD.

Now as I start to look at the z axis, (what's that called, the bridge?) what do we want to see? More pipe? Precision ground shafting? Your thoughts?

Mike...

I am assuming this is a front to back tilt? Not side to side or twist?


But it seems like a back panel must therefore be somewhat floating to allow this adjustment. The main load is in the front, which wants to tilt the carriage forward, so it seems like this panel would be pulling apart, negating its use. The best outcome would be that someone would tell me I am crazy.


No, it's side to side. The 3/4" shaft keeps it from moving front to back. Now that you mention it, I never thought about it tilting front to back. The panel I add in the back will make sure it can't move. I'll probably mount one end to aluminum angle with bolts, so I have some adjustment. I'll leave it a little short when I cut it. A second panel could be added in front the same way. I won't need this on mine, though.

As for your gantry racking, that's why I'm using two motors and leadscrews. I cant see any way to get sufficient rigidity any other way using the pipe and rollerblade bearings. Possibly by using a large panel across the bottom the full width of the gantry sides.

Steve. Thinking about that front to back tilt. There are 4 5/16" threaded rode, under quite a bit of tension. In order for the assembly to tilt, all 4 need to bend, and stretch a little bit. Not very likely. When I had it together, it seemed very rigid (except for the side to side thing :) ) Adding the back panel will make it even better, but if it weren't for the side ti side movement, I think the threaded rods alone would keep it from tilting.

We need more brainstorming.

As long as Mike's willing to build prototypes :) I think that's the best way to go about this. Last time someone tried this, there was too much brainstorming and not enough (any) building.

No, it's side to side. The 3/4" shaft keeps it from moving front to back. Now that you mention it, I never thought about it tilting front to back. The panel I add in the back will make sure it can't move. I'll probably mount one end to aluminum angle with bolts, so I have some adjustment. I'll leave it a little short when I cut it. A second panel could be added in front the same way. I won't need this on mine, though.


Ger, did you consider using turnbuckles or crossing your threaded rod that connects the top to the bottom? It sounds like you have a pair of parallel hinges and they need some triangular bracing. Just a thought, but it seems that the turnbuckles would be more adjustable than a solid piece of wood.

Mark

I even though about running some cables diagonally. :) I think the wood will be the easiest way.

Gerry, the next statement after the brainstorming comment was a reminder to me to start building a large pipe box. I just did not want to get too sidetracked in construction techniques, but rather get the discussion back to design (or whatever you call it). As of right now, I got nothing to really build because of open issues. You could help by finishing and testing your machine. :stickpoke

So the Z plates move side to side? The top can go left while the bottom goes right? I’m sure it is not that much, but still worth thought. I guess this is kind of a parallelogram thing. I bet this side to side movement is exactly what I am seeing on my gantry racking. The left wall can go back while the right wall is going forward.

Are you saying that the Z rods are also being used for structural support? You can cut them that precise?

I see a bit of carriage forward tilt on my machine unless I really crank on the bearing pressure. This would be reduced with larger pipe, but the same thing will want to happen. This seems to be an inherent problem trying to get a four wheeled vehicle driving on top of a pipe. Try it with your car. A larger pipe will help, but the problem is still there. Could you check this out on your carriage and see if it is worth worrying about?

Mike, nice drawings. You are a lot faster at that than I am. I thought you were out of time. :o Two thoughts. The Y box probably needs ends on it so it can be attached to the Gantry walls. If you build it, leave a little extra length on the pipes as the gantry walls may need to be a torsion box thing also. It seemed like all of the forces in the system end up in the gantry walls making them want to bow and twist.

Steve

Hello Everyone,

Just had a thought, first I love the elegance of Ger's machine but in order to stiffen things up we will need to put a piece across the top and bottom of the gantry structure. I don't think many are going to go for having two steppers on the x axis. I believe if we put the top and bottom on, maybe even build a small box at the bottom of the gantry this will eliminate the flex found in the gantry.

Now on the z. Is it possible, without loosing too much strength, to put a grove or dado down the gantry torsion box for the lead screw? This would eliminate the flex caused by the leadscrew being set to one side. This would also be just as easy to make using the template and router plan.

Also I bought all of the stuff to make one of the eccentric bearing bolts. I will post some pictures as soon as I can. I believe this will clear up a few of the lingering worries about adjustment.

What do you think?
Jimmy Southern

Now on the z. Is it possible, without loosing too much strength, to put a grove or dado down the gantry torsion box for the lead screw? This would eliminate the flex caused by the leadscrew being set to one side.

I wouldn't do it like that. I'd put the screw in front of the gantry torsion box, and mount the nut to a vertical panel in front.

Cutting through the skin of the torsion box takes away it's strength.

Could it be usefull if you all make a wiki on this subject ?

For example you could make a part about sliders, mentioning the different slider types discussed here.
With the good and bad sides of it.

And you could sum up the conclusions of this discussion.

This way your findings are nicely concentrated in one place.
Searching through all the mail in the threads for this info can be troublesome.
In a wiki it could be much easier and clearer.

Two thoughts. The Y box probably needs ends on it so it can be attached to the Gantry walls.


You spotted that eh? Very good. By the time I realized I had forgotten the end plates I was out of time this morning. I'll add them in tomorrow morning.

If you build it, leave a little extra length on the pipes as the gantry walls may need to be a torsion box thing also. It seemed like all of the forces in the system end up in the gantry walls making them want to bow and twist.

I was going to try the prototype with double thickness gantry walls. If that didn't work, I was going to add some ribs on the outside.

What did we decide on the z axis? Something like this? We can buy these on ebay...
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7532231770&sspagename=ADME:L:RTQ:US:1


Mike...

Hardware store design CNC router #1

I believe we as a group should stay away from things on ebay, as that kind of goes against the name of this thread. You may want to go for it yourself. Or offer it as an option. Looks nice. Too little for me I think. (48 oz with 20 tpi).

Steve

(Edit: although, that said, I want to be able to buy things from McMaster and MSC.)

Hardware store design CNC router #1

I believe we as a group should stay away from things on ebay, as that kind of goes against the name of this thread. You may want to go for it yourself. Or offer it as an option. Looks nice. Too little for me I think. (48 oz with 20 tpi).

Steve

I agree that we need to come up with something that we can build at home. So is that pipe on the z axis? Or precision ground shaft?

Mike...

Mine was 3/4" drill rod from MSC (about $12 for 3 feet). With RulonLR linear bearings from McMaster (about $4.50 a piece). All my part numbers are at home.

I realize these are not from a hardware store. But they are from a store that I believe will continue to sell them for years. This was my own little rule when I built my machine. You know, repeatable.

Steve

Hey Everyone,

I agree with steve. The only thing that should be an ebay item is the bearings. If you have kids you may not have to buy them. Inline skates, most of the common folding scooters, and several other common kid items have them. A nephew of mine gave me two scooters and a pair of rollerblades. They were well used and showed very little wear in the bearings. One pair of rollerblades has 16 bearings. Stay away from skateboards though the bearings are not near as good.

Lets try to build just as much as we can from the hardware. I want to show people that a quality machine can be built from common items found locally. :cool:

Later,
Jimmy

Hey Mike,

I was typing my post when your post came in. What if we use standard galvanized solid rod. It is available in three foot lengths, up to 1" thick. My local ACE hardware has it all the time. I have used it for the guides on two small press breaks I built, about two years ago. They are used at least three to four times a week. All I used was 1/2" black pipe reamed to 5/8" ID for the guides. No wear to speak of.

Hope this helps
Jimmy

That's interesting... reaming 1/2" pipe to fit over gal. solid rod. I can't imagine it's real precise.

How did you position those solid rods precisely?

Mike...

I'm working on the Y bearing shuttle. Which side should be adjustable, the upper or the lower. I'm leaning towards the lower...

Mike...

Top or bottom? I don’t think structurally it makes much difference. Seems like the top would be better to me. Easier to get to and you need 4” to 5” (or whatever) of clearance on the bottom so anything you add down there requires you to raise the torsion box.

What are you thinking about the shape/look of the shuttle?

Steve

I see a bit of carriage forward tilt on my machine unless I really crank on the bearing pressure. This would be reduced with larger pipe, but the same thing will want to happen. This seems to be an inherent problem trying to get a four wheeled vehicle driving on top of a pipe. Try it with your car. A larger pipe will help, but the problem is still there. Could you check this out on your carriage and see if it is worth worrying about?

Steve

I have to agree, the round guide way presents leverage issues that are hard to overcome, maybe these sketches will make it clearer. As you apply lift to the axis, a rotational force is easily applied to the guideway making it non-ridged. the truck can "skitter" around creating a torque about the axis of motion. This is almost imposible with a V way. I personally like using about a 2" square tube but smaller may be adequate.

Edit:

Another advantage to the square guide is that it can be solid mounted with no adjustment bolts required, If the alingment is off you just loosen it and place shims in the appropriate mounting locations, then tighten it back up.

Hey Mike,

You are right about the bushings not being very precice. I was just mentioning that to show how wear resistant the galvanizing is. I believe the way to go on that is to use the skate bearings riding on the solid rod. Have you looked at the build your idea HBLB guys ideas on the z axis? I'm not sure that is the way to go, but it looks like a very simple arrangement. Especially with the eccentric bolts on one side. I will post more later today but I have got to get busy here for a couple of hours :)

Be thinking about it.
Jimmy Southern

Hello Dieguy,

I really like the square idea from a straight engineering point of view. But from a DIY home built point of view I see numerous problems.

1. Getting the pipe located perfectly in alignment with the bearings, so the bearing is not riding on edge. This will kill the bearing quickly from side loading.

2. If you will look at your illustrastion you will see that the points of the two square pieces are almost touching. This does not leave any room for mounting without notching then drilling the corner of the square. This is not a major problem but could cause a newbie a problem. I know this is used to mount the bearing trucks on the JGRO machine. So this is not new. I believe with a little patience this could be a great solution but not the easiest.

3. Although the precision fit is not absolutely required, I do believe the tool impaired:) are going to have a difficult time with this.

I don't want to shoot down this idea especially on the z axis, but lets see if we can brainstorm a simple way to make it work. Maybe some simple geometric way of laying out the pockets so they can be cut, by hand, to make a template to route the pockets for the corner of the square. But we must end up with as close to perfect of a pocket as possible without a mill.

Let the Ideas Fly!
Jimmy

Hello Dieguy,

I really like the square idea from a straight engineering point of view. But from a DIY home built point of view I see numerous problems.

1. Getting the pipe located perfectly in alignment with the bearings, so the bearing is not riding on edge. This will kill the bearing quickly from side loading.

2. If you will look at your illustrastion you will see that the points of the two square pieces are almost touching. This does not leave any room for mounting without notching then drilling the corner of the square. This is not a major problem but could cause a newbie a problem. I know this is used to mount the bearing trucks on the JGRO machine. So this is not new. I believe with a little patience this could be a great solution but not the easiest.

3. Although the precision fit is not absolutely required, I do believe the tool impaired:) are going to have a difficult time with this.

I don't want to shoot down this idea especially on the z axis, but lets see if we can brainstorm a simple way to make it work. Maybe some simple geometric way of laying out the pockets so they can be cut, by hand, to make a template to route the pockets for the corner of the square. But we must end up with as close to perfect of a pocket as possible without a mill.

Let the Ideas Fly!
Jimmy
1) Actually the side loadings should be no worse that on the round design, as load is applied to the round design the bearing is going to want to move off the crown of the round tube causing a side load.

2) Actually the square tubing available has a radius on the corner giving adequate clearance for both the truck and the mounting. Mounting should be no more dificult to create than a round clearance, as I have said before it probably would require a router and a jig to finish the surfaces for mounting, but slight errors in the V angle should not be a big problem, A test fit and sander should be able to cure those error even if the angle is off a degree ot 2. 1 degree is only 0.017 per inch of run.

3) the precision fit is not really required, by assembling and then checking the alignment shims can be used to align the beast.

Hey again Dieguy,

Sorry for the all negatives on that last post. I had a customer to come in and lost my train of thought. Like I said before I really like the square idea. I was going to do pros & cons on the last post. Seems I only got the cons written down. Well here are the pros:

1. Depending on the size of the tube & clearance, we could stack several bearings on the shaft. This would give more surface contact. Thus eleminating tracks being worn in the tube and the need to rotate the round pipe. I really like this part!

2. Ease of alignment. If the tubing has been carefully installed and you have eccentric bolts on the trucks, alignment should be a breeze. No need to shim the bearings to get them dead center of the radius. I really like this also!

3. Strength: I have done a bit of research into the strengths and weaknesses of the round versus square. In this instance the square offers a bit more resistance to flex, but not much.

My conclusion is: If the fit can be made simple enough, this should be the best way to go. One glitch that we have failed to cover though is: this material is not available at most hardware centers.

So I will leave the reccomendations to the rest of the team. I personnally like it but may not suit the hardware plans because of availability.

Let us know, ESPECIALLY those that are in "hard to get" areas.

This is just my opinion though!
Jimmy

Hey guys, I'm a long-time lurker. I've been following this thread, its great... the creativity is awsome! Anyways I thought the square tubing was a really cool idea, and I thought of this: using angle iron instead of the square tubing. I drew a quick drawing in rhino to illustrate what I mean. I'ts crude, but It illustrates how simple it makes building the ribs of the torsion box. Thanks -Carl

izzlestar, welcome!

I plan to give the square channel a try. After pushing, pulling, and yanking my small pipe machine, I have noticed two things that I do not like. Although, hey, it’s MDF and pipe, and it ain’t all that bad.

#1) the carriage can roll forward. When I first tested it with a 30 pound weight hanging from the front, I discovered that the carriage was too weak. I rebuilt it with wrap around sides and am very happy with the strength. I was delighted that the bearing adjusters could bring it back into level with or without the weight. I dropped any further testing. I am a harsher critic now and can detect this roll by pulling and pushing on it. I cranked on the bearing adjusters until the motor stalled, and then backed them off a half turn. Pretty much solved the problem, but I am not sure I like that much pressure. So I just bought some 3/4” square channel at Home Depot (small I know, but it is very close to the 1/2” pipe that I am using). I plan to make a box to support it and report back This problem will rear it self more on small pipe, but if we can nail it there……..

#2) the gantry right side can move back and forth while the left is held ridged with the left mounted leadscrew. I have mentioned this before, but I spent some time last night watching it. Increased bearing pressure did not really help, but increased tightness on the two torsion box’s attachment bolts did. So what I plan to try is to move the leadscrew to the bottom center. To do this I need to build a new bottom torsion box, so I plan to make it stronger and increase the length of the top skin so it will fit into dados in the gantry walls. Maybe replace the T-nuts with threaded rod running all the way through. Again, larger boxes will help this problem.

Steve

Hey again Dieguy,



My conclusion is: If the fit can be made simple enough, this should be the best way to go. One glitch that we have failed to cover though is: this material is not available at most hardware centers.

So I will leave the reccomendations to the rest of the team. I personnally like it but may not suit the hardware plans because of availability.

Let us know, ESPECIALLY those that are in "hard to get" areas.

This is just my opinion though!
Jimmy


My Home Depot carries Square tubing and Angle iron, but the selection is not great and it is pricey. I know structurqal tubing is not really a hardware store item, it is readily available about anywhere in the world locally.

The angle iron is also a good idea and the 45's should be much easier to cut than a V. My only concern would be the attachment method. With tubing a large enough hole could be drilled in the corner to all the bolt head to be inside the tube ( use socket headed caps screws for this) but some sort of V shape or cone shaped washer would really be required. One might be able to use a flat head screw successfully too.

My plan is to pull the two square channels together with threaded rods outside of the gantry walls. (?)

Steve

I really need to stop posting so much but just had an idea. Build a square sided torsion box (easy). Cut two strips of wood the same thickness and length as the box. Cut two dados down each strip for the angle iron edges to rest in. Glue these strips to the top and bottom of the box. Attach the angle iron with threaded rod on the outside. I doubt you would need center mounting bolts.

Steve

Ok... I've been watching this thread... and wanted to chime in...

I like the whole anlgle iron thing that Izzlestar posted. that looks like a pretty clean way to make the ways for the X and Y axis... and with a good template the ribs would be easier and really stong since the angle could be 1/8" thick.

Are you guys planning to do a single leadscrew blelow the Torsion box? with a part spanning the gantry sides. Just curious... I'm looking at how you are planning to mount motors and such to what you are designing.

(Might want to go ahead and make the torsion box into a vaccum table with some holes in the ribs and a fixture for a vac hose on the rear.)

Hey Izzle,

Love the name by the way.

Welcome to the team love the design. This will greatly simplify matters, as far as the square design goes. This an elegant to the point idea.

As to the attachment, if this were an 1 1/2" angle iron piece and you have used the router ro make all the pieces the same, you could simply predrill & countersink the edge of the angle, well clear of the bearings track, and clamp with some epoxy or gorilla glue then screw the angle down. The "belt & suspenders approach"! I like it!

With two bearings per shaft,this thing would be tough!!!! This solves several design problems. Mostly the future wear & sagging problems.

Lets hear some comments guys. What do you think. Just my opinion Though!

Good idea Izzle, Dig deep and keep it coming!

Thanks,
Jimmy

P.S. I love out of the box thinking!

One of the problems that had bothered me about using angle iron was having to go to larger bearings or a new hold down style for the aluminum angle to keep the two angles from rubbing. Here is one possible hold down solution. I drilled a hole sideways through the angle and inserted a small bolt that passes through an eyebolt. This eyebolt then can be used as the hold down bolt. The angle pieces seem to have enough radius on the corners to keep them apart.

Steve

Steve,

That's looking good. Can you show me a photo of that mounted?

Mike...

P.S. I've always like this concept too. I wonder what it would take to make it work...

Mike, like this?

I always wanted to play with V-bearings. Someone on the zone found a cheap supplier for them in China, but you had to buy a hundred. Would not be hard to use up that many if we group purchased. I don't remember the name, going to go look.

anoel, like I was trying to point out in post #203 part 2, I believe we should drive the X screw in the center. This would call for a bar across the bottom of the gantry. My recomodation is that this is another really strong torsion box that is firmly attached to the gantry sides.

Steve

I don't want to shoot down this idea especially on the z axis, but lets see if we can brainstorm a simple way to make it work. Maybe some simple geometric way of laying out the pockets so they can be cut, by hand, to make a template to route the pockets for the corner of the square. But we must end up with as close to perfect of a pocket as possible without a mill.

Let the Ideas Fly!
Jimmy

You could make all the parts for the torsion box without the notches for the square tubing. Fully assemble the torsion box and afterwards use the edge of the torsion box as a fence and route out the notches for the tubing. This would be an easy way to make sure all the notches align well.




#1) the carriage can roll forward. When I first tested it with a 30 pound weight hanging from the front, I discovered that the carriage was too weak. I rebuilt it with wrap around sides and am very happy with the strength. I was delighted that the bearing adjusters could bring it back into level with or without the weight. I dropped any further testing. I am a harsher critic now and can detect this roll by pulling and pushing on it. I cranked on the bearing adjusters until the motor stalled, and then backed them off a half turn. Pretty much solved the problem, but I am not sure I like that much pressure. So I just bought some 3/4” square channel at Home Depot (small I know, but it is very close to the 1/2” pipe that I am using). I plan to make a box to support it and report back This problem will rear it self more on small pipe, but if we can nail it there……..

Steve

I'm not sure that the round tubing is solely responsible for this. Similarily, I'm not sure that square tubing will correct this.

I think that a major weak point in this system is the way the skate bearings are mounted. The bolts that are used as axles on each bearing is only mounted on one end, which allows for the axle to deflect. Tightening the bearings down preloads them but allso applies more friction.

Does anyone have any ideas on how to make the bearings resistant to deflection?



.

Hey guys, I was grinding away on this idea tonight: turn the angle iron around, so that the bearings ride inside the X axis... Hard to explain, but I drew it up in rhino again. The torsion box would be more complex... or perhaps you could build 3 of them. One for each side and the middle box. The thing about this design is that you could solve the problem of the leadscrew having to run on one side of the gantry... this way you could run it straight through the middle. The gantry could also be a torsion box design. Just an idea! -Carl

re angle mount
been playing with this seems to work on paper

There's really not much to the z axis, if I follow thru with the adjustable pipe idea. Just box it in, and add another bearing shuttle.

Here's what materialized on my screen this morning! ;)

Mike...

Hey guys, I was grinding away on this idea tonight: turn the angle iron around, so that the bearings ride inside the X axis...

Carl,

Can you send me that parasolid...

mykes (at) comcast (dot) net

Thanks,

Mike...

Does anyone have any ideas on how to make the bearings resistant to deflection?

I used 1/4" thick 6061-T6 aluminum angle. The bearings don't deflect at all, even under a LOT of pressure.

I used 1/4" thick 6061-T6 aluminum angle. The bearings don't deflect at all, even under a LOT of pressure.

I suspect using steel angle there would help as well.

You could make all the parts for the torsion box without the notches for the square tubing. Fully assemble the torsion box and afterwards use the edge of the torsion box as a fence and route out the notches for the tubing. This would be an easy way to make sure all the notches align well.

I'm not sure that the round tubing is solely responsible for this. Similarily, I'm not sure that square tubing will correct this.

I think that a major weak point in this system is the way the skate bearings are mounted. The bolts that are used as axles on each bearing is only mounted on one end, which allows for the axle to deflect. Tightening the bearings down preloads them but allso applies more friction.

Does anyone have any ideas on how to make the bearings resistant to deflection?


Well one way would be to increase the bearing diameter to say an OD of 1.5 inches and get it move away from the corner of the angle iron. The Ebay source for skate bearings (VXD I think) has sealed electric motor bearings in this range and bulk quantites. Then support the axle on both ends with a piece of 2" square tubing mounted to the bearing support angle. Drilled it for the axle and notched it allow the bearing to "stick out" of the side of the tubing. That should eliminate any axle flex.

As far as axel flex goes, I do not think this was what was contributing to the roll that I noticed. I was using small pipe and this allowed the use of a single nut as the bearing spacer. The total axel length was therefore just 1 inch. The use of angle as the rail will also allow the use of such short axels. Using thicker aluminum or steel as the bearing holder is probably a good move. I think what I was seeing was either caused by the tilt on a round pipe problem or it was the four point bearing adjuster flexing.

Steve

anoel, like I was trying to point out in post #203 part 2, I believe we should drive the X screw in the center. This would call for a bar across the bottom of the gantry. My recomodation is that this is another really strong torsion box that is firmly attached to the gantry sides.

Steve

Rather than a torsion box... perhaps something like I used when I built my last router.

http://home.insightbb.com/~nnoel/CNC/DCP_0671.JPG

Strong and doesn't deflect under the pushing and tugging of the nut.

Has anyone looked into using sliding glass door rollers? They're cheap and available everywhere. I went to home depot the other day and picked up a two pack for 5 bucks and they roll like a dream on 1/4” angle iron. My idea is to make a truck that looks something like the ShopBot or that green gantry in some of the banner ads on this site.

anoel,
what are the size of your x and y? Drill rod I assume?

X is 25 mm and Y and Z are 16 mm

If I had to do it again it would be 45mm on both X and y and 25 on the Z

25 is not enough for the X. Just a little too much droop in the center.

Nathen, seems like we are talking about the same thing. I just built mine torsion style with skins. I kind of cheated and there are only four supports inside and I can tell that when I try to rack the gantry. I am starting to believe in using a fair number of ribs. A sheet-rocked wall is a torsion box. A wall with 16” centers is a lot sturdier that 24” centers.

Man your machine is good looking. Love the curved gantry walls. Everything I build is either square or round.

Steve

Has anyone looked into using sliding glass door rollers? They're cheap and available everywhere. I went to home depot the other day and picked up a two pack for 5 bucks and they roll like a dream on 1/4” angle iron.

I'm using sliding door bearings right now on my machine. I used 1/4 round rod that fits in the groove of the rollers. Nice and tight. The rods are fastened to mdf by drilling small holes in the rod, and nailing them in. That part all works fine. Everything rolls like a dream. However, there is a problem with the bearings. The slop in the inner portion of the bearing creates movement that cannot be tightened up. If you grab the bearing in the center, and rock the outer beraring side to side, you can see what I mean.

To fix the slop, I used two pieces of cutting board plastic to act as guides to prevent the wobble. It mostly worksed, but it introduced more friction into the system.

I picture is worth a thousand words, so I will try to take some pictures this weekend. carriage_details.jpg shows what I did with my y axis. I also will be trying to eliminate the slop this weekend in a different manner. I'll keep the group posted.

There's really not much to the z axis, if I follow thru with the adjustable pipe idea. Just box it in, and add another bearing shuttle.

Here's what materialized on my screen this morning! ;)

Mike...

How much z-axis travel are you shooting for?

Man your machine is good looking. Love the curved gantry walls. Everything I build is either square or round.

Steve

That machine has been done for a whle now, still going strong. I actually cut all of the parts with my second CNC router I built. This one is much , much better. I'd still like to do something with fully supported rails though. I'ts still not as rigid as I'd like it to be. but this was a step in the right direction. I'm curious to see where this one goes. I'll try to contribute here and there when it gets closer to refinement time.

How much z-axis travel are you shooting for?

After having built a few machines now. I'd suggest at least 4" Z clearance and about 8" or more of actual Z travel. It's a real pain in the ass to have to jog the machine off of zero to be able to change a bit because you don't have enough clearance.

Howdy to all,

Sorry, I didn't get to do much yesterday on the zone but a fellows got to make a livin' sometime.

I finally had some time in the workshop yesterday. I managed to throw together one of the eccentric bearing bolts that I have mentioned in previous posts. I shot some pictures but I have never posted pictures on the zone so I hope it works.

Materials list and the dimensions of the parts:
Bolt: 1/2"x 1" with nut. Actually on the machine I would use a nylock nut.
Standard skate bearing.
Bearing bolt: 5/16"x3/4" Flush or Flat head bolt
1 standard 5/16" washer.

This setup gives over 3/16" of easy adjustment!

Howdy again,

I forgot to mention, it took probably 10 minutes to make this part. No real need for alot of precision if you use a drill press. After drilling the hole, I chucked the 5/16" tap in the drill press and used a pair of adjustable pliers to turn the chuck. I did this because I "suck" at starting a tap straight :) . It was just easier for me.

It is a very simple and cheap way of getting alot of room to play with. I think, if incorporated in the design, this will make the newbie more likely to get a good tight machine.

Tell me what you think. This is not my idea and I wish I could give credit to the originator on the zone, but I lost the original post. If anyone knows the originator of this idea please post it so they will receive credit.

Hope this helps
Jimmy

Jimmie, as a newbie I can say that I really like the eccentric bolt, and thanks for the detail on using the tap in a drill press - a method I use myself, but I hadn't thought of using a wrench on the chuck !
On my setup, which will be quite small and lightweight, I will only be using three bearings per side, two on top and one (the adjustable one) underneath.
Is there any advantage in using four when the lower one is only resisting the tool climbing up on the work ?

Howdy again,

I forgot to mention, it took probably 10 minutes to make this part. No real need for alot of precision if you use a drill press. After drilling the hole, I chucked the 5/16" tap in the drill press and used a pair of adjustable pliers to turn the chuck. I did this because I "suck" at starting a tap straight :) . It was just easier for me.

It is a very simple and cheap way of getting alot of room to play with. I think, if incorporated in the design, this will make the newbie more likely to get a good tight machine.

Tell me what you think. This is not my idea and I wish I could give credit to the originator on the zone, but I lost the original post. If anyone knows the originator of this idea please post it so they will receive credit.

Hope this helps
Jimmy

i think finding the person responcable for the idea is going to be hard
seen this arangment in old looms dating from the 18xx's but obviously not for this application of its use :)
Dave

Hey Guys,

I was just checking the posts and read over mine, I noticed I had left a bit of advice off. If you decide to use the drill press, first: DO NOT DO THIS UNDER POWER, second: Go by the hardware store and pick up some anti skid tape. This can be put between the chuck key post holes, to keep the wrench from digging into the soft metal of the chuck. If your not careful the pliers or wrench will ruin the surface of the chuck.

Thick leather & a pipe wrench work well also. One day I am going to run across a tapping machine, or build one :) .

This method works well for me but maybe someone has an easier way. If so let me know.

Dave,

I was talking about the person who posted it here first :) . Yes the general idea has been around since the industrial age started. It has held up well, I think. There is still lots of life left in this one!

Thanks everybody
Jimmy

Hey Guys,

This method works well for me but maybe someone has an easier way. If so let me know.

Dave,

Thanks everybody
Jimmy

The Bob Villa & Sears special strap wrench! :D
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00945560000

As far as axel flex goes, I do not think this was what was contributing to the roll that I noticed. I was using small pipe and this allowed the use of a single nut as the bearing spacer. The total axel length was therefore just 1 inch. The use of angle as the rail will also allow the use of such short axels. Using thicker aluminum or steel as the bearing holder is probably a good move. I think what I was seeing was either caused by the tilt on a round pipe problem or it was the four point bearing adjuster flexing.

Steve


Steve, I put my gantry together and noticed some problems. It does roll front to back. When I had it together before, I couldn't put any force on it to notice. I'm going to make some side panels, that fit around the box and tubes, and attach them after the threaded rod is tightened. These along with a rear panel (and probably a front panel behind the router) should stiffen everything up. Mike was by to take a look, and I think he agreed with me.

One other problem (annoyance, actually). When I had my table and base assembled last, it was in the winter. With the humid summer, my torsion box table has gotten a good 1/16" or more wider. with no adjustment, I wouldn't have been able to get it back together, because the holes in the endplates were closer together than the torsion box pipe supports. I was able to put it together myself in the winter, but it took 3 people to get it together now. Along with a hammer and some clamps :) So, it looks like a bit of adjustment on one side might be beneficial. Maybe even both sides. Although if built in a dry climate, or in the winter, I think you can get away without it. But if you build in the summer, be aware that things may get loose in the winter when the humidity goes down.

Does anyone think it would be impractical to run 2 smaller pipes and bearing trucks per side of the gantry rather than one large pipe? Will it help with the flex ?

ok guess i have taken a different approach

rather than using mdf for the structure its a mixture of angle iron and unistrut

not going to win the award for the best looking machine

but on the upside i guess i don't have to do seasonal adjustments that depend on the air mosture

unistrut i would say falls into the hardware store catogory , although it is avalable , and widely used in the building industry

well the design seems stable enough , still got the x drive to finish , and need to source some better steppers as the (60oz) ones i got are having difficulty driving it

i like the look of the machine your putting together , just wonder if mdf is the best material to make it from?
this machine used 2 ,3Meter lenths of unistrut , could realy do with another lenth of it and £12 a lenth not overly expencive

still may re design the z axis ,and it needs a solid support piece between the y rails to stop twisting of the y axis in the y plain , but its seems rigid enough otherwise


Dave

Does anyone think it would be impractical to run 2 smaller pipes and bearing trucks per side of the gantry rather than one large pipe? Will it help with the flex ?

I think it would be a lot harder 2 make sure all the pipes line up, and need double the parts. But, using 2 pipes on top of the gantry would eliminate the problem I have with the forward twisting.

Gerry, how about having the holes in the ends for the pipe oversized and use threaded rod to pull them together?

Mvaughn, have to think about that one. Might have promise for a small pipe machine.

I have not had much time to build a new torsion box for my Y using angle iron. I am really getting leery about implementing it. It seems so much more natural for a beam to be lying in a trough, and not lying over an edge. I can picture it rocking.

As far as building it, it is also hard to get a reference for square when the ends aren’t. The only way I see making it right now is to build it square and cut the points off. The only way I see attaching the angle iron is threaded rod at the ends pulling it together, unless you want to tap the ply (which I don’t). Any construction ideas?

Steve

How about something like this?

Steve, I put my gantry together and noticed some problems. It does roll front to back. When I had it together before, I couldn't put any force on it to notice. I'm going to make some side panels, that fit around the box and tubes, and attach them after the threaded rod is tightened. These along with a rear panel (and probably a front panel behind the router) should stiffen everything up. Mike was by to take a look, and I think he agreed with me.


Yep, I gotta tell you guys... Gerry has one heck of a nice looking machine! Once he boxes in the bridge, I think all his wiggle movement will be gone. It's encouraging to see his bridge moving on the gantry rails. There was no friction at all. Combine that with a 2 start acme screw, and you've got a machine that'll fly. I'm looking forward to continue on my machine.

Mike...

P.S. It was real good to meet Gerry. He's a real professional, and has lots of good ideas too!

That is really cool .. putting the whole in the bolt head to make the ecentric .. whod of thunk it ? u must be a machine / tool and die guy !

that bold head should probably me a high strength bolt ( designated with 6 strikes across the head not 3 ? ) but then it's kind of a pain to drill with the higher carbon steel -- more dull bits to sharpen in the grinder ;(


Howdy to all,

Sorry, I didn't get to do much yesterday on the zone but a fellows got to make a livin' sometime.

I finally had some time in the workshop yesterday. I managed to throw together one of the eccentric bearing bolts that I have mentioned in previous posts. I shot some pictures but I have never posted pictures on the zone so I hope it works.

Materials list and the dimensions of the parts:
Bolt: 1/2"x 1" with nut. Actually on the machine I would use a nylock nut.
Standard skate bearing.
Bearing bolt: 5/16"x3/4" Flush or Flat head bolt
1 standard 5/16" washer.

This setup gives over 3/16" of easy adjustment!

Hi, I'm new to the forum and I thought I'd share some info from my recent research efforts.

I've been looking for linear slides recently and I came across a German company called "Hettich" who make loads of things including heavy duty drawer slides that range from 10kg to 136kg load capacity. They are reasonable priced (depending on the complexity and load bearing ability) plus they are available at my local hardware store in Sydney, Australia.

Here are some pics I found to give you an idea (results of Google image search for "Hettich slide" or "Hettich quadro"):
Quadro End View (http://www.hettich.com/hft/diy/images/quatro_picto.gif)
Quadro rendering (http://www.hettich.com/com/hettich/images_content/Quadro_Illustration.jpg)

The "Quadro" range looks really interesting because it looks like it will take loads from all angles.

I've ordered a couple (http://www.hettich.com.au/index_146.htm) of the normal ball bearing, 450mm long, 45kg models from an Australian supplier (http://attiwillsonline.com.au) so I can evaluate them. They cost about AUD$27 each. I was hoping to mount them end-to-end and see if I can extend their range.

Check out their
"Hobby Tip 4 - details of drawer slide systems" (http://www.hettich.com/hft/diy/data/pdf_t04_schubladenf_ze.pdf)

Their websites are a pain to use, but the Australian one is OK:
Quadro (http://www.hettich.com.au/213_220.htm)
Ball bearing runners (http://www.hettich.com.au/index_137.htm)

Share the knowledge!

regards,

Aras Vaichas

Hi Everyone,

Looks like we have had a bit of progress.

So far I am leaning toward the design sketch by Dieguy. Couple of changes, 1st add one more bearing to each of the axles at least on the top ones. 2nd use the eccentric bolt on all of the axles. I believe this would give enough adjustment to get every thing in perfect square and level.

I also noticed someone was having moisture problems on the wood. This is my recommendation: Most hardware stores carry polyester resin for doing fiberglass repairs. Coat all of the MDF sheets with this before doing any cutting. this will seal the majority of the board. The only problem with this is, the edges may swell slightly if you wait to long to cut it up after coating. After you have cut and glue assembled your parts go back and coat all exposed(open) MDF with the resin. After a couple of coats you could drop this in a lake and not bother it with moisture.

Chronon1,

No, I am a signmaker by trade. I am a tinkerer by genetics and neccesity :) . I don't think we will exceed the strength of a grade 3 bolt. If I remember correctly, the shear strength for a grade 3 bolt is almost 20,000lbs, in a 1/2" size. The maximum rated load limit for the bearing is 1000lbs and this is shock load rating. Not to mention we have not even discussed the 5/16" bolt that holds the bearing to the 1/2" bolt. So I don't think the weak link is the grade 3, 1/2" bolt :). If this were for major lifting or load carrying I would agree. But for an MDF based machine I believe it will hold up to the strain. The only thing I would do to increase strength would be to move the hole a little closer to center. The example I posted was a bit to close to the edge. I didn't ever measure I just "eyeballed it" :) .

Hope this helps,
Jimmy

Hi Everyone,

Looks like we have had a bit of progress.

So far I am leaning toward the design sketch by Dieguy. Couple of changes, 1st add one more bearing to each of the axles at least on the top ones. 2nd use the eccentric bolt on all of the axles. I believe this would give enough adjustment to get every thing in perfect square and level.


Hope this helps,
Jimmy

Thumbs Up Jimmy, make sure you take pictures and let us see you progress.

I am also looking at one that is a bit more radical. I want to model it and try it before I offer it up. It is really not a garage store type design but could be produced for very minimal cost. I think I will try it on a small router setup to see how it works out.

I worked on the bridge this morning... It's totally boxed in to try to avoid any movement problems.

Next I'll work on the tool mounting, and finally I'll come back and see if we left us any room for the stepper motors and acme shafts. :confused:

Mike...

Great work Mike! Are you using Solidworks? Any chance you can make your models available.

Great work Mike! Are you using Solidworks? Any chance you can make your models available.

Actually, that's modeled in UG NX. But I can export a parasolid if anyone is interested. I'd like to get the basics of the machine modeled before I start exporting... Can you read parasolids? How about acis?

Mike...

I worked on the bridge this morning... It's totally boxed in to try to avoid any movement problems.



I think you'll get a little front to back flex, depending on the loads involved. A 1/4" plywood panel on each side should be enough to prevent this. Easier to do it now than find out you need it later. :)

I agree with Gerry. Maybe you could also make your pink plates and the top and bottom of the Z out of the same piece of wood to strengthen the Z.

Steve

Hey Mike,

Mike, I really need you to do me a favor. Please look at post 241 and my post 245. If you have some time I need to see a quick 3d rendering of the idea with the changes I mentioned in post 245. If I use this I will probably use 1-1/2" angle iron. This will also help the other builders who are thinking of this as an option.

Don't spend alot of time on details, I just need to visualize it with the sizes and spaces correct, to make sure there are no interferance problems.

Let me know if you can do this. Also if you need any more information pm me or just post it. I usually check back 3 or 4 times a day.

Thanks a bunch,
Jimmy Southern

Jimmy, DieGuys idea does look pretty good. I didn't pay much attention to it when he first posted it. It won't be any easier to cut perfect matching 45° angles on all those parts. It may een be more difficult than drilling a hole in each one, as the angle needs to be perfectly at 45°. Looking at Mcmaster Carr, i also noticed that angle iron has a thickness tolerance of ±.01, which is quite a bit.

Also, I'm not sure of it will prevent the forward rocking that I'm seeing.

Jimmy, DieGuys idea does look pretty good. I didn't pay much attention to it when he first posted it. It won't be any easier to cut perfect matching 45° angles on all those parts. It may een be more difficult than drilling a hole in each one, as the angle needs to be perfectly at 45°. Looking at Mcmaster Carr, i also noticed that angle iron has a thickness tolerance of ±.01, which is quite a bit.

Also, I'm not sure of it will prevent the forward rocking that I'm seeing.

I think it has to be more ridged than the round tubing design, the bearings have full contact and any deflection ony increase the pressure on the bearing where with a single point contact on round tube the possibilites for rolling about the tube axis increases. That is impossible on a V.

The tolerances on angle iron are large but generally I have found that mostly those apply on a piece to piece or even a run to run basis in the manufacture, single pieces tend to be much more uniform, typically the same within 0.001. One might even consider Aluminum angle, the full line contact of the bearing would tend to prevent galling.

Alignment tends to be easier. Simple Sheet metal shims placed behind the angle can be used effectively to adjust the location of the angle so perfect cuts are not really necessary. Even a dab of hot glue can be applied to prevent the shims moving out over time. Several options can be use to create the angles, but I think that rough cutting the angles on the stock and assembling the torsion box and then making a jig to hold the router @ 45 while using a straight edge clamped to the top/bottom of the torsion box would work great. A good finish reference plane is established with the torsion box and the straight edge is a natural for the other axis of freedom.

It'll definately be more rigid than round tubing. As for the tolerance, that's what I was thinking.

hmm
an idea for making the angle iron method adjustable
and removing the need for a 45deg cut
use 2 square bits of mdf rotated through 45deg and bolted to the torsion box
if slotted holes are used then this would allow for adjustment

there may be a better way but this seems both easy to make and solves the problems in having to cut a 45degree angle and also allows for alignment

dave

Hey Dave,

I like the idea! But I have a question. Do you have the capability of doing a quick 3d rendering? there are alot of people who have a hard time visualizing the 2d stuff. Also for the plans, if nothing else we could include this for an optional build idea.

Also what size angle did you have in your design? I believe it needs to be at least 1-1/2" for the large machine. I know the torsion box design is self supporting but I also know MDF. :) I only have a dxf viewer, no capability to see measurements. I really wish I was good at cad work. It would make sharing ideas so much easier.

Gerry,

What do you think about this? I like the idea of being able to add more than one bearing per axle to eliminate the wear tracks in the rail. I really think we are on to something here.

Everyone let us hear your opinions.

Thanks,
Jimmy

...maybe someone has an easier way.

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00945560000

FINALLY, a good use for those strap wrenches. :D

Rance

Jimmy. I wouldn't add any bearings. It would be virtually impossible to set them up to carry the load equally, imo. and if you use steel angle, wear should be negligible.

Hey Dave,

Also what size angle did you have in your design? I believe it needs to be at least 1-1/2" for the large machine. I know the torsion box design is self supporting but I also know MDF. :) I only have a dxf viewer, no capability to see measurements. I really wish I was good at cad work. It would make sharing ideas so much easier.

Gerry,

What do you think about this? I like the idea of being able to add more than one bearing per axle to eliminate the wear tracks in the rail. I really think we are on to something here.

Everyone let us hear your opinions.

Thanks,
Jimmy

I have to agree with Jerry on this one that wear will not be an issue with steel angle.

1 1/2" angle should give plenty of strength and room to make attachment.

ok hope this will be better

in the picture the piece of wood represents the torsion box , the block of aluminium (with the hole in the middle) the support piece
and the white angle iron the runner

ok so the angle iron will be bigger than the 20mm piece shown , and there will be 3 slotted holes in torsion box and support piece that will allow the suport to be adjusted
the same for all points of contact along the sides of the torsion box

ignore the clamps used they where used just to hold it together for the photo :)

this better ?

Dave

Hey Guys.

Thanks for the replies. I am going to defer to your judgement, Gerry. I have not built one of these yet but I have heard people complain of the bearings wearing tracks in CRS rod. We will give it a shot with a single bearing.

For the designers who are trying to make heads or tails of the discussion, here are the highlights so far on this particular design idea:

1. Still using the torsion box.

2. Check Dieguy's post#241 for the angle arrangement

3. Look at Achiestdragon's post with the dxf attached. I think his idea will be easy to implement. But this will be a bit of a long way around approach. Lots of adjustment though.

4. We are going back to the single bearing per axle and 1-1/2" angle iron rails.

So if anyone would like to knock out a simple 3d rendering for us to put the "ole' evil eye" on feel free to. It would be greatly appreciated.

If we can get a good rendering together that I can print out to see while I build, I will throw together a quick prototype to see how hard it will be to build and align.

Has anyone seen mike, it's not like him to be this quiet :stickpoke . HEY MIKE WHERE ARE YOU AT!
Sorry didn't mean to yell.

Holler at me,
Jimmy

My vote is to keep it simple and easy to build. We supply router templates that take care of all hole and critical placement. Go with non-adjustable pipe as rails, torsion box supports, and all motor and bearing mounts are NEMA 23 so the builder can start with all-thread and move up to different leadscrews and bearings as they desire.

Steve

My vote is to keep it simple and easy to build. We supply router templates that take care of all hole and critical placement. Go with non-adjustable pipe as rails, torsion box supports, and all motor and bearing mounts are NEMA 23 so the builder can start with all-thread and move up to different leadscrews and bearings as they desire.

Steve

My vote is we keep it simple as well and easy to build, We supply router templates for the V shape and go with angle iron and single bearing per axle. The angle is adjustable by simply shimming the back of it. is not that critical if we allow for back shimming with washer shaped shims which in effect give a pad contact for the angle.

I think someone needs to build a prototype of the angle iron.

Jimmy, I wouldn't bother with those eccentric bolts. As long as you drill the holes in your angle with a fence on a drill press, they should be close enough.

I think someone needs to build a prototype of the angle iron.




I am headed there if this damn JOB would ever leave me alone. :tired: :( (nuts)

Hey Everyone,

Well, Mike is building the round pipe machine prototype so I guess I will start to build the angle iron. I will probably build a small trial run out of scrap MDF to see how the idea works. Before anyone says where are the motor mounts and blah, blah, blah, realize this is the mechanical testbed. I have no intentions of powering what I will be posting pictures of. This one will be purely for mechanical research.

It will probably be toward the end of the week before I will be able to post anything, as far as pictures go. But I do thank all of the people who are posting diligently with ideas, It has been a big help to all of the newbies like myself. I hope I did not offend any of the electronics guys but I am trying to make sure we stay on track.

Please be patient and if you see an error in the design mechanically, please let me know. I am going to try doing it without the eccentric bolts and use mikes idea which I belive is the same as JGRO's plan. We will see how it does. Even though I have a complete wood working shop I am going to limit my tools to the drill press, router table, router, and circular saw. I hope to be able to show this can be done on a very small budget.

We will see how it goes,
Jimmy

Hey Dieguy,

TELL THEM ABOUT IT I'M SO MAD I CAN'T! :rolleyes: Seriously, I am self employed and don't have time to do anything. But this machine is a shop need!!!! So if I have to stay up nights I have no choice. Maybe $8000 VS $1000 thats about the only choice I have.

Thanks
Jimmy

Hey Jimmy and DieGuy,

About the angle iron rails, I did play in the shop a week ago with this after I got the bearing holders to mount with the eye bolt so there was no interference. I am not totally against it; I just found it hard for me to make it work and am not sure that it will really reap the benefits that it seems to promise. I bought several sizes of both angle and square channel to try. I am a really big proponent of a solid fixed non-adjustable rail so I tried to get either to work with precut ribs. Two problems that I ran into were getting a nice clean repeatable 45 degrees that the rails balanced on, and once I had some ribs, I found it hard to keep them in alignment when gluing up the box. I admit it, I gave up. Shims might solve the first problem, and some kind of indexing cut would help with the second problem (or trim them after the box is completed which would not be so fun).

True, the round rails allow the bearings to climb around the pipe, but with some pressure they do stay where they are supposed to, even on my .85” pipe. I believe that larger pipe will help this quite a bit. A side benefit that should not be ignored is that this climbing can be used to level an individual axis.

Please prototype in your shop and let us know. MDF and/or ply is cheap, you can try a lot of stuff for $10 in wood. Jimmy, use all of your tools and skills at this point. We can develop newbie techniques later.

Steve

ok , well i seem to be getting on ok with a design using unistrut

about half way though the controls
and waiting for some draw slides so i can finish the x axis

should be fully operational in a week (if all parts ordered turn up by then )
although i does not look as good as the mdf designs and could be built looking better i guess it is strong and rigid , guess i may look at improving it once finished
there are some bits that could be better , and maybe if i spent the time i could have all the metalwork nicely finished ,

so far only tools used are drill , hacksaw, spanners ,file , vice , and screwdrivers

no plans as yet ,
cost well 2 * 3M lenths of unistrut costs £12 for a 3M lenth

Dave

It's been a busy weekend, but I'm back. I mostly have a couple questions for you guys this morning.

1st: can one get 1" thick nylon for an antibacklash nut? Is there such a thing as a 1" thick nylon cutting board?

2nd: does anyone have a scale model of a nema 23 stepper motor handy?

Attached is the screenshot of what I am thinking for the anti-backlash nut. I used this on my first machine with the 1/4-20 thd rod, and it worked well. I remember seeing the photo of the guy that made a 1/2" acme tap and tapped nylon also, but I don't remember how thick that nylon was.

Mike...

Mike,

You might be able to trade something to this guy for some 1" ( http://www.cnczone.com/forums/showpost.php?p=102516&postcount=1 ).

I saved the text for the home-built tap in my Palm Pilot. I have tons of notes there for when I need them. It makes a great database.

Nice backlash design, I think I'll try it with mine. :)

Rance

-------------------

From http://www.cnczone.com/forums/showpost.php?p=61073&postcount=88

>> Lead Nuts-UHMW(like Delrin)
3/4" thick

Cut 9" of threaded rod to make an ACME tap with your drill press. Use a cutoff wheel to cut reliefs in the tap.

Drilled a 3/8" hole and used the homemade tap. Use the drill press to hold the tap perpendicular to the lead nut, and turn the drill press by hand to tap it. I had to run the tap through several times until it stopped removing material from the nut.

Put the UHMW lead nuts in the freezer to shrink them slightly. Then chuck the tap in an electric drill and run it through the nuts several times.

The nuts should spin freely and have no noticible backlash.



Can one get 1" thick nylon for an antibacklash nut?

I remember seeing the photo of the guy that made a 1/2" acme tap and tapped nylon also, but I don't remember how thick that nylon was.

1st: can one get 1" thick nylon for an antibacklash nut? Is there such a thing as a 1" thick nylon cutting board?

2nd: does anyone have a scale model of a nema 23 stepper motor handy?


1: Those 1" cutting boards do exist but only in the larger kitchens at restaurants, hotels, hospitals etc..
I also saw some at a machinebuilder's shop, even more than 1".
So I know where I can get some but have no idea where you could just buy it.

2: Have several Nema 23's here, what do you want to know?

Luc

Thanks Rance,

That's exactly what I was looking for. Do you also have the URL to that guy's web page? He shows a neat photo of the finished AB Nut. If you have it, can you post it here?

I might design it with 3/4" nylon cutting board. I think you can get that at a hardware store that sells cutting boards.

Hey Lucas, I was wondering what the chamfer on the main body of the motor was. Can you measure across flats on the chamfer?

Thanks,

Mike...

P.S. I roughed in a Nema 23 motor, and it looks like the adjustment screws will be in the way of the motor...

Hey Lucas, I was wondering what the chamfer on the main body of the motor was. Can you measure across flats on the chamfer?

P.S. I roughed in a Nema 23 motor, and it looks like the adjustment screws will be in the way of the motor...

Sorry, but English was only 3th language wen I went to school and I still have some problems with those mechanical/technical terms.
Chamfer is rounded off I think so I suppose you want to know the diagonal dimension of the mounting plate?

I have 3 different brands and they are all different, 2 are rounded off the 3th has a simple 45° cut.
The largest one measures 76.5mm = 3.01", the other 2 are a few mm smaller.

I had a similar problem on the motor mount, some screws were in the way so I used 4 standoffs and mounted the motor higher, this also allowed me to try another style of stepper: round with 2 mounting ears (Mitsumi, Minebea etc..).
Doing it like this creates flexibility in the design.

Mike,

Do you also have the URL to that guy's web page? He shows a neat photo of the finished AB Nut.
Go to the page link, click his name and you'll see his home pg. under Contact Info. about half way down on the right. You can also see his work log page at the very top right of the link also. ( http://www.cnczone.com/forums/showthread.php?t=4716 ). See also http://www.nukesilo.com .

What's an AB nut? I used to be an RC nut but now I'm only a woodworking nut, a CNC nut, and a Hang Glider nut. :D

Edit: Nevermind (Anti-Backlash). I just looked it up. :) Still can't find his AB nut though.

Rance

After visting the hardware store (OSH) I decided against the angle iron. It just didn't seem very straight. It seems to have weird kinks in it that could end up being a real pain in the butt. I also think the way we'd have to mount it would be silly. Tapping MDF doesn't sound like a good idea. But I really liked the square rail idea, so I looked at the square tube and thought it looked straighter in general. In regard to making the ribs for the torsion box: I think the idea of building one out of wood, aluminum, MDF... whatever, and using that as a template for a router to trace would be sufficient in providing a set of even ribs.

interestingly the quality of the material depends on the store , could say the same in some shops about ply and mdf sheets being warped and not square , like most shops you would buy good items not b grade stock

if you went to a food shop you wouldent buy broken eggs if thats all thay had to offer , angle iron is usualy straight , guess thay only stock damaged goods there
or thats all they have left

i will add that you should go for steel angle iron as apposed to aluminium as aluminium will deform easy

dave

btw like the box section idea
although putting nuts on the ends of the studs in the middle of the rail is going to be a pain

Mike,

( http://www.cnczone.com/forums/showthread.php?t=10067 post #12 )

Was this the AB nut you were looking for?

Rance

It took a little while, but I finally found it...

http://www.buildyouridea.com/cnc/IG-88/phase_eight/phase_eight.html

I don't remember it hanging down like that... I thought it was tapped into the end grain so to speak. Oh well...

I just hope I am not creating a weak link by doing it this way... see attached...

Mike...

You guys are doing a bangup good job. Keep up the great work!

After visting the hardware store (OSH) I decided against the angle iron. It just didn't seem very straight. It seems to have weird kinks in it that could end up being a real pain in the butt. I also think the way we'd have to mount it would be silly. Tapping MDF doesn't sound like a good idea. But I really liked the square rail idea, so I looked at the square tube and thought it looked straighter in general. In regard to making the ribs for the torsion box: I think the idea of building one out of wood, aluminum, MDF... whatever, and using that as a template for a router to trace would be sufficient in providing a set of even ribs.

I like the square tube idea as well, the only issue is attachment but threaded rod run all the way across and a triangle shaped "washer" made from aluminum would work nicely. The hardest part is drilling a hole large enough on the corner of the tube to get a socket wrench through to tighten it all up. You could even double nut it to make sure it didn't loosen up over time. you might have to raise the bearing on the axle to clear the hole in the tube crown.

As far a using angle, I sure would not tap the mdf, I would cut a cross hole and drill through to it and place a half round looking "washer" and nut on it.

PS I love your rendering! :D

As far a using angle, I sure would not tap the mdf, I would cut a cross hole and drill through to it and place a half round looking "washer" and nut on it.

Instead of tapping the MDF, just use woodscrews. Drill and countersink the angle, and carefully predrill the MDF with the correct size bit, and screw it on. It might be a good idea to reinforce the MDF with CA, though.

Ok, I came up with another idea using angle iron, I thought that I would post it to see if you guys think it is viable. It is patterned it after the "shopbot" rails, except it doesn't use the dualV bearings. I think I found away around spending 20 some odd dollars a bearing to use angle iron. The "newrail4" image shows how the outside bearing holes can be slotted to allow the bearings to be adjusted. The inside angle iron (rail) is 1.5 inches and the outside angle iron (truck) is 2.5 inches. Enjoy! _Carl

I don't remember it hanging down like that... I thought it was tapped into the end grain so to speak.Mike,

I agree w/you, it's best not to hang down that far. You may have missed it but his prolly works well because it is also deep lengthwise along the axis. It's not a plate, it's more of a square block.

Your attachment 'looks' as sturdy/sturdy enough. And also uses less material. :)

Rance

Hey Dave,

I like the idea! But I have a question. Do you have the capability of doing a quick 3d rendering? there are alot of people who have a hard time visualizing the 2d stuff. Also for the plans, if nothing else we could include this for an optional build idea.

Also what size angle did you have in your design? I believe it needs to be at least 1-1/2" for the large machine. I know the torsion box design is self supporting but I also know MDF. :) I only have a dxf viewer, no capability to see measurements. I really wish I was good at cad work. It would make sharing ideas so much easier.

Gerry,

What do you think about this? I like the idea of being able to add more than one bearing per axle to eliminate the wear tracks in the rail. I really think we are on to something here.

Everyone let us hear your opinions.

Thanks,
Jimmy

Hi Jimmy
Yes l can I have AutoCAD 14 and 3d studio that will render most 2d or 3d DWG.
My design has gone in a different direction to the Hardware store design CNC router
I have gone for 16mm liner rails all round 50mmx75mm steel main frame and removable
Torsion box design so I can jig each table for the parts to be routed I have attach a dxf of my router and if you can skesch a dwg in format (windows metafile tif gig bmp jpeg) with dimension on I can 3d it and render back in dxf wmf bmp. Wood be interested in a vacuumed design if Torsion box design if you have one It will be for holding down berich ply light ply and aly

ok
sorry for another dxf in 2d
but i do seem to prefer the idea of using box section rather than angle iron

trying to use the dfx to show how it could be posable to mount it easy without the need to fish around inside it for nuts and washes

using screws , the holes for the screws can be drilled on the flat sides of the box , near an edge so as not to interfere with the part the the bearings travel on

i also have a thought about alignment , think i solved that also but need to draw it , not got time at moment , but will try to get it done later today (in 3d :S)

ok rough 3d drawing of it attached

the box would be hollow box section , the two bits running parallel are mdf
and the bit sticking down is the cross suports of the tortion box also mdf
the bit sticking down is 1 of a number of pieces accros the lenth of the tortion box as the other designs have shown

sorry but not used blender in ages and could only get it to change the colour of all bits at once :(

using the mounting method like shown in my last dxf it would offer 2 advantages doing it this way
alignment should be posable if the mdf that the rail rests on is screwed to the tortison box , and the extra support would hold the rail accross its entire lenth

Dave

Wow, you guys have been busy...

Blender, what is that? A CAD package?

Is there anyway you could make those .bmp images larger, or change to a .jpg format?

The pipe design is nearing completion. I just need some kind of thrust bearing on the end of the acme thd rod, and a tool holder.

Any suggestions for the thrust bearing?

Mike...

Ok, I came up with another idea using angle iron, I thought that I would post it to see if you guys think it is viable. It is patterned it after the "shopbot" rails, except it doesn't use the dualV bearings. I think I found away around spending 20 some odd dollars a bearing to use angle iron. The "newrail4" image shows how the outside bearing holes can be slotted to allow the bearings to be adjusted. The inside angle iron (rail) is 1.5 inches and the outside angle iron (truck) is 2.5 inches. Enjoy! _Carl

Carl,

I really like your concept. I think it has a lot of promise!

Mike...

Blender is a free modelling and animation package.

What do you guys think of Steve's Thrust Bearing? It looks simple enough!

http://www.cnczone.com/forums/showpost.php?p=95602&postcount=61

Mike...

P.S. Steve, can you tell me more about the bearings? They just slide over the 1/2" acme rod, right? Got a part number, URL or a source for the bearing?

If it works OK, it's by far the easiest way to go. Not the cheapest, but not too bad. How's it working, Steve?

Hey,
I really, really like it. The picture that is posted did not work and really shows how not to do it. I went with radial bearings and two MDF plates. If are you planning on a 1/2x8x2start screw, I’m not sure on tapping your own AB nut, but I never attempted it. I don’t have a good picture of the final towers, but I attached one that I posted earlier using 3/8x12 rod that I had lying around. The concept is the same, to quote myself:

“Leadscrew mounting can help three problems at once: whip, backlash, and motor wear. The trick is to “fix” the screw at the motor end and not let the motor’s bearings take any of the load while firmly attaching the screw to the frame. It takes 4 nuts, two MDF blocks, and two bearings in a configuration as in the picture. The MDF pieces form a thrust plate. The bearings sit in the recesses and are back to back. The procedure is to loosen the motor coupler, lock the two nuts nearest the motor together, and then tighten the next nut to compress the two bearings together against the thrust plate. Finally tighten the outside nut to lock it all together. Now tighten the motor coupler. Firmly attach this to your machine with nuts.”

To do the same thing with 1/2x8x2 you will need shaft collars and spacers instead of nuts, as nuts were not available. I attached a picture of my Z that uses this. In both cases, the two bearings are tightened firmly against each other to remove any leadscrew backlash. The far end is a single bearing that has either a nut or a collar that is then tightened to keep the screw in tension. I had to slightly “turn down” the OD of the screw with a drill and file to get the bearings to slide smoothly up and down the end of the screws.

Bearings MSC 3543390
Screw MSC 01205996
Collars MSC 87856779
Spacers were either hardware store Nylon or small sections of copper pipe.

I am probably going back to 12tpi for the Z so I can lift my heavy router easier. The other two axis are happy with the 4tpi screw.

Sorry for the ramble,
Steve

Ok well, I headed over to OSH and picked up some angle. The only problem was that the largest that they had was 2". So I picked that up and some 1" to use as the rail. The original called for 2.5" for the truck and 1.5" for the rail. After a little re-designing I came up with this. (attached) I'm really happy with them, I see a lot of potential... I don't mean to keep hammering you guys with this stuff, I'm just trying to contribute, even if it isn't using the torsion box ideas (which rock btw...) ...Anyways, the only problem with the idea is that if you try to twist the truck around the rail, it has some play. But I don't see that being a problem when two rails are mounted parallel... Lots of good stuff here guys! _Carl

Carl,

That's looking good. Please keep the ideas and the pictures coming.

Mike...

P.S. Are you going to add wipers to get the dust off the top surface of the angle where the bearing rides?

Mike,

To answer your question from the CheapCNC thread (http://www.cnczone.com/forums/showpost.php?p=102852&postcount=50), yes, I do like the direction it is taking. I REALLY like the torsion box design with the rails on the inside (post #289). It leaves very little room for flexing. You might consider widening the table in the Y axis to keep swarf off the rail though. I believe it is superior to the JGRO approach, but they both have their tradeoffs. (I'm going with the rod rather than the angle or diamond.)

I'm gonna go back and review the entire thread but if you think you can really build the H/W Store machine for $200 that is great news. :) I could see the controller and 2 steppers costing that much. Don't get me wrong, < $200 is closer to my price range. Initially, working from the cost backwards for my own target machine cost of <$100, I ruled out even the minimal electronics to drive the average steppers(100oz/in?). With that, I chose to go with floppy steppers and just use their existing electronics. Consequently I'll have to scale the cabinet/gantry down to using scavenged printer rails, and bearings from old disk drives. This in turn limits my first machine's use to small wood projects and PCB etching, which I currently don't see as a problem.

Have you guys defined the target electronics for this machine? I would be VEEEEERY interested to find out if you all have found a way of getting around the high cost of the controller for this machine.

300 posts in less than a month... I think you guys have the target audience. :)

Rance

I haven't worked out the entire price for the hardware yet. I know we have 2 sheets of plywood @ $29
2 packs of skate bearings at $29 a pack
12' of pipe at an average of $3 per ft
tube ?
angle $10
hardware ?
acme thd rod ?
coupling?

So I am at $162 so far...

For the electronics, since I know nothing about electronics, I am going to suggest a 3 axis controller from xylotex for $145
http://www.xylotex.com/#3axis

3 steppers from ebay... figure about $100
http://cgi.ebay.com/SKC-NEMA-23-STEPPER-MOTOR-200-OZ-IN-3-0-AMP-NEW_W0QQitemZ7545436684QQcategoryZ50924QQrdZ1QQcmdZViewItem

A 24v power supply $39
http://www.web-tronics.com/dualout100wa1.html

A 24 v cooling fan $2.50
http://www.allelectronics.com/cgi-bin/category.cgi?category=220&item=CF-209&type=store

So for the electronics I am at $287 so far.

Throw in a couple bucks for wire and connectors, and you're in business.

Your first project is to build a wooden enclosure for your electronics... I can't find the picture right now, but when I do I'll attach it here...

Mike...

I haven't worked out the entire price for the hardware yet. I know we have 2 sheets of plywood @ $29
2 packs of skate bearings at $29 a pack
12' of pipe at an average of $3 per ft
tube ?
angle $10
hardware ?
acme thd rod ?
coupling?

So I am at $162 so far...

For the electronics, since I know nothing about electronics, I am going to suggest a 3 axis controller from xylotex for $145
http://www.xylotex.com/#3axis

3 steppers from ebay... figure about $100
http://cgi.ebay.com/SKC-NEMA-23-STEPPER-MOTOR-200-OZ-IN-3-0-AMP-NEW_W0QQitemZ7545436684QQcategoryZ50924QQrdZ1QQcmdZViewItem

A 24v power supply $39
http://www.web-tronics.com/dualout100wa1.html

A 24 v cooling fan $2.50
http://www.allelectronics.com/cgi-bin/category.cgi?category=220&item=CF-209&type=store

So for the electronics I am at $287 so far.

Throw in a couple bucks for wire and connectors, and you're in business.

Your first project is to build a wooden enclosure for your electronics... I can't find the picture right now, but when I do I'll attach it here...

Mike...

well the steppers you mentioned are 6 wire and look like unipolar , the driver is a bipolar and the steppers are 3v ones so you would need large dropper resistors to correct the voltage ,(((edit yes they will drive them but the current looks over for that controler ))))


maybe you would be better using http://www.xylotex.com/3AxSysKit.htm

kit of steppers , driver , psu and fan

that way you know everything should be matched , rather than having to get bogged down in the maths needed to calculate the correct drive voltages for other steppers
, i got a stepperworld.com fet3 econamy system
well the steppers are under powered , the driver slow
anyway i modifyed the driver and got some bigger steppers , and built a psu for it , looks a bit of a mess but works http://www.whipy.demon.co.uk/cnc.jpg

going to have to redo the controls later and do away compleatly with the stepperworld driver

i am using 8 wire hybrid steppers that can be wired in eather bipolar or unipolar modes so it will leave the controler option more flexible
ac5711575225m from http://www.arceurotrade.co.uk/

Dave

p.s.
if using a wooden case for housing the electronics use a metal ( aluminium ) sheet EARTHED with the electronics mounted on that
and take usual care like unplugging before opening :)
most electronic component shops sell plastic project cases they are better suited
in my case im using a ip66 case as the machine is used outside so needs to be water tight

Hey Dave,

Your're right about the steppers. And that package deal that you found although a little bit more expensive, at least ensures that all the components match. :banana:

And I'm sure you're right about the enclosure too. Can anyone suggest an affordable enclosure for inside use?

Mike...