Does this look like a CNC Machine ????

[flyrc]

Well here is another new bee.. trying to build his own Home-Made-CNC machine. Thank to all the info I found on the this site and the web.. I've managed to come up with the following....desing. (the cutting area should be 10in X 36 in and Z will travel about 3in )

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[flyrc]

OK so maybe that Image does not look anything like a cnc... but I think you will agree.. after the parts are cut out it will start looking like a CNC machine ! (If you could not tell half the board will be used to make a table and the other half will be my cnc machine)... Actually I've already had the parts cut out of MDF at the local Home Depot this Friday ! ) they did a great job.. saved me lots of time.. and the cuts are as true as I could have hoped for...been working most of the weekend on it and its actually starting to look like a CNC Machine .. have not taken any pics yet ) but here is what it will look like )

[wjbzone]

flyrc,
Hard to tell everything from these drawings.

I would want to be sure that from where your router will mount, that a standard length tool bit will reach your workpiece.

Looks like the thickness of the mount plate plus the thickness of the YZ carrage will take away a lot from that reach.

Bill.

[flyrc]

You are correct ! ( I made the final adjustment on the actuall working parts last night ) before final assembly. The tool will extend about 3 in below it's mounting plate, the mounting plate will start (0 position) 3 in above and total z axis travel allowing it to reach the surface.................I made the CAD Drawing to help me get a visual Idea of how the overall parts would fit but - made the final decision as I was building. I put the parts together as I was building and noticed I was not going to move very far. Since I had the trucks/bearings so far apart.............. So far I think its all going to work ( worse case I will mount the tool on a fixture and then mount that fixture on the block that slides on the z rails making it adjustible. .... Good eye Bill ! (I will take some pic's today I'm sure they will be more clear than "words"

[cncadmin]

Hey flyrc, I'm from tucson.

[flyrc]

Cool !.. ( I've been in Tucson for 1 and 1/2 years ) .......... Loving it.. while I'm not at work that is.... actually its not so bad ! ( I plan to use my CNC for cutting out Balsa part for building Planes. I found some pic's of balsaman's machine and that is how I got interested in building my own machine. ( I made up my mind to build a machine when I was trying to cut some small wood part and just could not get them as true as I wanted.. holding them down with my fingers and cutting with a rasor saw was not working for me hmm or maybe I just needed an excuse to build one .. I Searched low and high on the internet before I came accros this site... (Thank every one for all the Ideas )

[flyrc]

ok here are are some pics of what I have so far...( def. starting to look like a cnc

[flyrc]

except for a few parts most of it still need to be bolted down, .........will probably start working on the nuts today and tommorrow so I can finalize the size of my all thread.. ( going to be using delrin (made from 1inX1in bar) and 1/2-13 all thread from local home Depot... The all thread will probably be the only think I need machined.. ( going to have to turn one end down to 1/4 to connect to my steppers )

[bcromwell]

Where did you get the small linear rails and bearings?? How much did you run you?

Bryan

[HomeCNC]

I don't want to sound negitive so I hope you will only take this as constructive input. If you find that your router motor is vibrating when cutting you can blame this on your standoff design. You may want to think of a way to remove the long standoffs to help make the machine more ridgid.

[flyrc]

The small rails I got from E-bay payed 35$ for a set ( I purchased two sets total 70$ plus shipping ) each set had 4 bearings/trucks I cut one to use on the z axis...... ( they are only 14.5 in long was looking for something at least 20in but those usually start getting up there is price... ( I had to realy monitor E-bay to find them.. ) I made the axis longer.. so if someday I find some longer ones at a good price.. I may change it over..but for now it will have to do

[flyrc]

Jeff,

as for the stand offs, in the pic it only shows 1 on each bearing, (I just dry fit the parts) its set up to accept two on each bearing .. total of 8.....(the z axis shows two and it seem stable) I need the space to place the nuts for the leadscrews behind the moving part.... ( I did have plans to cut small MDF blocks and place them above or even below the rails to make up the distence... (but the standoff seem like a quick and easy solution but you are right I may pay the price for that later... I also plan to cut mostly balsa with a dremel or was thinking of buying a rotory tool from PROXXON... (for now I will cross my fingers and hope the smaller tool does not cause to much vibration...giveing me problems) I'm going with a small tool mostly because of its application and also the fact that I live in an Apartment.. the noise factor... although our place seems to have thick walls If you guy's have any tool recomendation.. I think the dremel is widely used.....maybe cecause the proxxon tool is not so commercially availble.. (ie.. i've never seen one in the home centers.. but I found a local dealer)

[chuckknigh]

I understand his concern -- your mount can be modelled mathematically as a cantilevered arm. I had a similar question a while back, and the cantilevering was a concern for me too.

In theory, the cantilevered arm may be a problem...in practice, it probably won't be, especially if you're doing extremely light duty work like cutting balsa.

I've heard this from more than one person, and now Eric (BalsaMan) is proving it true. No matter how well you think you built your first machine, it is only practice for the next one.

Fair warning, though...BalsaMan is building a big router, capable of cutting metal, as his new machine. And he started out wanting to cut balsa...just like you.

I'm paying close attention to your project -- I finally finished the adirondak chairs that were my "next" project, and have some time to work on my own CNC machine, now. Got any hints for me? You're using a moving gantry design...same basic design as I intend to use.

-- Chuck Knight

[flyrc]

Chuck

I had the some concerns about the way I was going to mount the z axis,
but mostly because of the design I'm using..... for what should be the x axis... I’m using only
two bearings one on top and one the side.

for the most part all the design I've seen in pics use.. at least 3 bearings.. (top, bottom and on the side) the most extreme use 3 but at 120deg from each other.

as I was still making final design choices I could see my machine falling over due the weight of the gantry, and the missing third bearing. But in any case I kept the design as is for simplicity.

Again due to the light duty work I don’t expect a problem but only time will tell..
currently if I apply very pressure to the z axis the structure hold strong so any reservations I may have had about those points are gone. (for now!)


but while any one machine cannot do every thing you like, I think it will be some time before I build a second……still have lots of questions.. (specially on the software end but I will hold off until I am at that stage)

I'm sure I will not have a need for cutting metal. my biggest concern now is what cutting tool to use since I live in a 2 bedroom apartment..(I’m sure the neighbor would not appreciate me making all kind of noise) part of the reason for the small cutting tool. No need for any large router on this machine.


Chuck the only advice I can offer right now since I don’t have a proven machine.. is maybe the thought process I used to get where I am...

I had the following requirements...

1. Building had to be simple... (since I sold all my tools I’m down to just a drill press cordless drill, I did borrow a miter box from a friend) storage cost where adding up to more than my tools where worth….but that is another story

2. The cost had to be with in reason... I had $500 in mind
( I may still be able to meet this, have to add up my receipts)

3. see number 1. (So far the only thing I will have someone else do is turn down the all thread to attach to the motors)

but before I started building I did spend a good month considering the diff possibilities as far as designs, I had considered a moving table as I though that a gantry would be to heavy , but due to the space required for the cutting area I wanted I ruled that out. Now that it’s together I don’t expect the weight to be a problem.

But I am starting to wonder if the all thread was the right choice.. the x axis is over 46 in long.. (but I will use it for now if I need to I could change to an acme screw with little effort , plus changing it I’m user would put me over my $500 mark)


Later! (hmm did I write all that )

[balsaman]

If I may suggest, you could put a couple braces across the back of the gantry to make the bridge a "C" shape. If you have flex, it will be that gantry bridge MDF sheet twisting. Been there done that. My last design was a "T" shape and If I did it again I would have gone with a "C".

Looks great. Keep it up!

Eric

[chuckknigh]

Originally posted by flyrc
[B]Chuck

I had the some concerns about the way I was going to mount the z axis,
but mostly because of the design I'm using..... for what should be the x axis... I’m using only
two bearings one on top and one the side.

How are you addressing lift? The router, when lowered into the wood (and even Balsa offers some resistance) will be met with a resisting force...an upwards thrust.

for the most part all the design I've seen in pics use.. at least 3 bearings.. (top, bottom and on the side) the most extreme use 3 but at 120deg from each other.

I've come up with several bearing designs, myself...the one I'm going to try to prototype today (if I can find a new belt for my drill press) uses 2 bearings and angle brackets. But, one will be above, and one below, at 45 degrees to each other.

Not truly ideal, but I don't have a sheet metal brake with which to bend the "proper" angles.

If captured "between" the two rails, it should offer resistance to lateral and vertical movements.

but while any one machine cannot do every thing you like, I think it will be some time before I build a second……still have lots of questions.. (specially on the software end but I will hold off until I am at that stage)

If you do a search, you'll find a thread called "I think I figured it out!" or something similar, started by me. It deals with the electronic and software side of the CNC machine -- the gantry, etc should be fairly straightforward, but the interface is what confused me.

Yeah...here it is. It's a direct link to that thread.
http://www.cnczone.com/showthread.php?threadid=438&s=

-- Chuck Knight

[flyrc]

Balsaman,

Thank for the tip, I had seen other pics where people did add some bracing (making I beams) to help stiffen/strengthen their machine. ( I’ve use up all the long pieces of MDF so I will probably use some hardwood ) I've only left a 3/4 "lip" on the end of the gantry bridge it’s 20in across and seem solid now but I'm sure the extra reinforcement will help and after the first few cuts to make sure things are square I will use glue all around.

Luis

[flyrc]

Chuck,

I think the forces on the z axis will be negligible, (you ever had a CAT walk on you while you sleep ?) they place all there weight on one small foot…. !

The biggest tool I will be turning I expect will be 1/8 diameter.. (I expect the weight of the full gantry to be about 10lb maybe less..

10 lb of weight displaced over 1/8 diameter I don’t think it will be an Issue.

But you are right this is all still R & D for me. (Time will tell)


As for the electronics.. I was trying to make up my mind between the stepper world FET-3, and xylotex.. (I finally decided on the xylotex board) it should be here today, (I still need a power supply it will probably be a week before its here)

Luis

(Thanks to every one for your input ..... keep it comming... short status - > I finsihed making the Delrin Nuts yesterday not much to show for now but, I think I will be close to completion by the end of this weekend I expect the Power supply will hold up completion...

[flyrc]

Just wanted to give all interested parties an update,

Since last post I have finished all the nuts, made all the bearing blocks ( MDF construction)

Installed the lead screws, the short 14 “ (10” travel) y and 7” (3.5”travel) ” z axis move smoothly. The longer x axis 40” while it moves with no real resistance, when I rotate the lead screw with my hand (motors not set up yet) it get a swinging motion…

Looks like the combination of the long lead screw cheep metal its made of caused it to hand down when ever the gantly is at an extreme end. I expect I would have some problems if my motor turns the lead screw very fast…(Guess I will not know until I get my motors spinning.)

Still left on the building list will be

1. (turn down lead screws)
2. drill holes on motor mount and bearing mount for x axis,
3. bolt on machine top ( surface when material will sit)
4. mount and complete the z axis
( made a minor change in final design so that I can mount z axis with out having to remove linear rails and bearings.. It was a pain in the b…. to have to do it each time I fitted the parts. Just mean I will have another layer of MDB

I expect this list to be completed over the weekend and will post some pics, for all to see…

At this rate I should be looking at cutting tools and Software by end of next week… (so far, looks like TurboCNC is the most popular.. have not used it yet..so still have more learing to do.

As for the cutting tool I was thinking of using a MiniCraft Rotory tools,
Here are the specs on it…

Voltage 0-18V DC
Maximum output 30 watts
No load speed 0-30,000 rpm
Chuck type Collet
Chuck Capacity 1.0, 1.5, 2.3mm
Cable length 1.8m
Weight 125g

The RPM’s are up there with the specs for Dremel, do you guys think this is good for balsa and light ply. If you guys have used one of these let me know.. I’ve only seen one in a hobby shop, it was very quite compared to the Dremel but not sure if it has what it will take to do the job… !


Thanks,

Luis

[sidi_steve]

The one thing that stands out as a possible concern is:

>Chuck Capacity 1.0, 1.5, 2.3mm

These sizes may be appropriate for your intended use, but without seeing it, I couldn't say whether you could modify one of the collets to accept a larger bit. So, just be sure you can get the cutting bits you need and plan to use in a shank size to fit your new rotary tool.

Steve