First I'd like to say howdy to everyone, and thanks for making all this information available.. I have learned so much and haven’t even touched the welder or soldering iron yet...

Oh, and please let me apologize for the monster post... but it's my first, so I have lots of stuff to cover...

Now, in all my reading I remember seeing something said that I should start off smaller and then work up. This just isn’t an option for me as 1) I'm impatient, 2) I just don’t have the resources to do something twice, and 3) I really don’t see that big of a difference in a small machine vs. a large one, everything is just bigger... ok, so at this point I think I have the perfect recipe for disaster... perfect, time to push forward... :devious:

So as the title says, I'm a total nooooobie to cnc. I work around cnc machines at work all day, but never have the chance to "crawl inside" to see what makes one tick. I have been doing lots of research, and for what I want (a 4' x 8' usable cutting area) I think I have decided to go with bipolar steppers and drives... I think that this will fall in my budget, and I feel confident that I can make it work for the accuracy I need.

Goals of my cnc machine:
1)Be able to cut and contour in 3d a full 4x8 sheet of mdf/ply for signs, speaker boxes, cabinets, and anything else I can dream up
2)Convert the machine from a router to a plasma table and have the ability to cut at most 1/2" mild plate steel for some prefab kits in designing
3)Have the ability in the future to add a 4th axis for doing all that nifty stuff, chess pieces, baseball bats, table legs, and so on...
4)Do it on the cheap, and I mean on the super cheap, I’m talking maybe $500 to $750 give or take to get the 3 axis running...

What I see that I need
1)A legal full copy of mach 3
2)The parts to build the driver circuits
3)Stepper motors
4)Steel for the table
5)Linear drive components
6)Steel
7)Bearings, linear slides, bolts wire, and a bunch of other little stuff….

What I don’t have and wish I did
1)Milling machine for making the parts to get my cnc going
2)More money

What I have at this point:
1)A large shop (2400sq-ft) to build, test, and run the machine
2)Computers, that will run mach 3 with no problems
3)Electronics background in design, and prototyping
4)Mig welders
5)A plasma cutter than can more than handle the 1/2" plate
6)A steel yard about 4 miles away from my shop
7)The ability (knowledge) in structural design to build pretty much anything that I can dream up given enough time
8)2 metal working lathes, one a mini 7x12 with 3 jaw chuck, an the other a 100 year old 10x24 lathe with 3 jaw chuck and independent 4 jaw
9)The demo version of mach 3
10)Rhino version 2
11)Some crazy ideas
12)Someone that just might pay for the mach3 for me
13)A boss (at my regular job) that is into this and wants to help (and is cool too!!) yea I know that’s a first
14)Someone that can mechanically or photo etch the driver boards for me for nothing more than the cost of materials
15)A design for the driver boards and sources for the parts that I don’t already have in house (I’m planning to use the l297/l298 design)
16)A 3/4 hp router and some bits
17)Lots of empty spaces in my breaker box, and the knowledge and ability to add more circuits as needed, and a “proper” amount of fear!
18)An austron 35amp 13.8v supply in a 24 space cabinet on wheels with 2 17Ah gell cell batteris for backup and momentary current draws over the 35amps..(im planning to put the drivers, computer and any other electronics in this cabinet as well)

My plan
1)Learn a bunch more
2)Finalize the design I want to use
3)Get the motors that I’m going to use
4)Build the driver circuits
5)Test the drivers and motors on the desk with mach3
6)Begin building the table
7)Assemble
8)Troubleshoot, troubleshoot, repair, redesign, build, troubleshoot, repair
9)Use the machine and giggle like a schoolgirl when it finally works
10)Upgrade the stereo in the shop so that it’s loud enough to be heard over the router. (and really annoy the neighbors at 3am) TURNABOUT IS FAIR PLAY!!!

My current design and thoughts:
Build the table pretty much like the one that I saw on http://www.inshorepowerboats.com/cnc%20stuff/CNCROUTER.htm
With a few changes… I like the y and z-axis setups, so I will probably replicate this. But the x-axis is using rack and pinions and that’s a little outside my budget, so here’s my thought. I have some and can easily get more #40 drive chain. My thought was to either lay the chain along the top rail of the table frame and have the gears ride in that (still need to investigate this and how much slop there would be) and use that like a rack and pinion. The other idea I had was to suspend the chain along the insides of the rails, and have the x-axis drive gears interface the chain there. The chain would be pulled taught and would make an upside down “U” where the drive gear would be at the top, and then 2 idlers would make the other bends, this way the chain is around 180deg of the pinion gear. Either system would be replicated on both sides with a connecting shaft between, so there would be no chance of the gantry racking diagonally… then use one of the 500oz*in motors I found on the net geared 10:1… figuring 300rpm max (I have no idea what this should be, I just picked a # outta the air) on the motor and a 1” diameter gear for the pinion, my math says that I should get a max speed of about 90ipm. So, if ya’ll will, please rip this design to shreds and show me what I’m missing…

Project5k

oh, while im thinking about it, i was considering using something like 2"x2"x1/4" angle top and bottom on the x axis for the long slides.. i could turn some v groove wheels on the lathe... my worrie is how much variance will there be in the angle iron that will cause the slides to not be absolutely true straight and flat, and how much will i cause when i weld it all down...

Well,, at least you know you have a recipe for disaster. Most people building an 18"x24" machine will spend $750. Building a 4x8 machine for that is totally unrealistic, unless you get virtually everything for free.

It's likely that chain drive will have far too much slop. You'll quickly find out that 90ipm is painfully slow for a 4x8 machine. A 3/4HP router is really too small. If you plan on running your stepers on 13V, you won't get anywhere near 90ipm. While a lot of people want to use their machines for both routers and plasma, I'm not sure if I've really seen anyone that does. They have different requirements.

Good Luck. (you're going to need it) :)

Ok fair enough. This is exactly why I'm on here, to pull from the vast experience that every one has. If you noticed, the #1 item in my plan is to learn a bunch more before going any further...
One thing that I had considered, but was leaving as a fall back plan was to build the table 48x48 with support wings to either end, so that I could index my stock, cut half, move it, and then continue. This is of course not my preferred method, but I think with enough careful planning, I might be able to make it work good enough for what I’m going to use it for...maby not.. anyone got experience doing it this way?

Regardless of what the final table size, my main interest at this point is to see if some of the principals of my design are flawed, and I’m seeing that they are. If the chain has too much slack in it, then I will have to figure another method... that’s fine, that’s what I’m trying to do, is to learn.

Ok, so let’s go through this, one step at a time....
Chain, bad idea....

How about the angle iron "tracks" and v groove wheels for the x-axis? I can see the potential for there to be some slack in this as well, but I was wondering if anyone had ever done this, considered it, and so on…

12v isn’t enough... ok, here’s my thinking on this... I figure to have any kind of margin, I need at least a 30amp supply... (I like to design my electronics with at least 25% extra capacity) so what should I be shooting for minimally? 24? 48? I’ve seen lots of different #'s on this...

90ipm did seem a bit slow, but I was using this figure more to see if people agreed with my math, and how I got to that #... having it take over a min to travel the length of a 4x8 sheet would be aggravating, but would work, yes?
What kind of ipm should I be shooting for? In my example I have the motor geared 10:1. Figuring that I’m guessing my gantry will be around 50# and working the math backwards, I would need 1600oz*in on the x-axis shaft with a 1" pinion. 1600/10=160. Now, this should accelerate the gantry at 1g. Not accounting for frictional losses and so forth. So lets call it 200 to make the math easier. If I use one of the 500oz*in motors, that would mean that I could cut my 10:1 gearing down to 5:1. This would make the motor minimum 320oz*in plus friction. And would make my feed rate 180ipm...now I understand that the faster you run a stepper, the less torque that it can produce at high speeds. Increasing the feed V will help with this some, but not totally overcome the torque curve...

My question is this. Since I don’t have that much experience with this, what would be a decent ball park RPM# to plan for on a nema 23 motor at say 24V or 48V? This is one thing that I haven’t found enough information on... My original guess was something like 300RPM. Is this too fast? On a 200 step/rev motor this would be 1000 steps per second. My electronics should be able to handle this. But will the motor do this with any torque?

If I figure 150RPM motor speed, the 5:1 gearing, 1” pinion then I’m back to roughly 90ipm rapids… I could go to a larger motor and less gearing, but I’m trying to get a baseline so start from…. If you all agree with the math and how I’m getting my #’s then I can make adjustments to the design once I get some kind of ballpark figures… While speed is an important factor, its not nearly as important to me as it might be to some…

One thing that I think I understand is that a lead screw would take less torque to move the same load than the rack and pinion, but will require a higher drive speed… a 50# gantry accelerated at 1g on a 5tpi screw would require approx 25oz*in not allowing for losses. But to get 90 ipm I would have to turn the screw(or nut) at 450rpm…. Ok this seems a little fast to me… but at 25oz*in, couldn’t I get away with say 1:2 gearing on the 500oz motor…that would then put the motor speed at 225rpm and the input torque at 50oz*in…but would also reduce my move per step accuracy from .001” to .002”

As for the cost, the $750 is a target, but is not the absolute final #. The software will most likely be paid for, and the steel is one thing that I have quite a bit of.. and can get more at a somewhat decent price. 2x2 box tubing comes in 24’ sticks and is $28 for 16ga and $47 for 11ga. I figure I’ll need something like 6 sticks to make the table frame, and then I can use something else for the actual bed… so lets just call that $300, the motors im figuring will cost something like $200, so that’s $500, the drivers are going to cost me $20 each to build (I have most of the parts already) so that’s $60, so $560 total, so that leaves 190 for everything else…so $750 does come up short… and that’s fine, it was just a ballpark # to aim for… Even if I end up putting $2k into it to get it going.. that’s ok, it will just take more weeks to do it…I’m really aiming for a up and running date of the first of next year.. so I have a little time to get my plan together, save up some $$$ and build it…

I have seen a router driven by chain, and the builder claimed it worked well for him. But it's the only one I've seen. (It's not on this site, I don't think)

Shopbot's use V-Rollers on angle iron, or at least the older ones did. www.shopbottools.com

Also, see this: http://www.cnczone.com/forums/showthread.php?t=3673

Motor supply voltage. At least 10 times the motors rated voltage, up to maybe 20 times. More voltage = more speed, up to a point. To much voltage = too much heat.

What speed (ipm) shold you shoot for? As much as possible. The router motor you use as a spindle will probably be the limiting factor in how fast you can cut, and 90ipm might be adequate, but I'd try to shoot for rapid postioning moves of 200ipm or more, the faster the better.


Your gantry will probably end up weighing close to 150lbs., if not a lot more. Mine is a wood torsion box with about 32" of travel (40" overall length) and with the Z-axis, probably weighs about 70lbs.

How fast can you spin a Nema 23motor? Depends on the torque curve for that particular motor, drives, and supplied voltage. Maybe 200rpm, maybe 1000 or more. Can vary greatly. You need to consider the entire drivetrain package, and optimise everything to work together.

$2K is a lot more than $500 to $750. To build a decent 4x8 router (not good, just decent), figure $2K minimum. Jmo :)

Thanks for the information... i'm still doing more research.. and i started drawing this whole thing in rhino, so i'll try and post some renderings of it for yall to take a look at...
also while im thinking about it.. i found this site that has some guide rails for sale, and wanted to see what ya'll thought....
http://www.cadcamcadcam.com/index.asp?PageAction=VIEWPROD&ProdID=133

i dont know why, but 1/4" wide seems a bit narrow to me, but what do i know....

That #2 track will work fine. Keep in mind you'll need 2 tracks per side, at about $100 per track. $400 + 8 wheels = $500 for just the X axis.

If you think you'll need bigger, go to www.bwc.com

ok, so here are a couple of the renderings that i have done in rhino so you can more easily see what im planning, the cavities in the v groove wheels is where the bearings will go, right now the plan is that the outter flange of the wheels is 3" diameter(its what stock i have) and the bearings will be 2"OD... all of the frame is 2x2 box tubing, and the y axis slider is 1x2.. i still have to work up all the propultion stuff, but im still thinking that i might just try and go a different route with the chain drive, im starting to think that maby crossing the chains is the way to go... this would put the x axis drive motor on the gantry, which may be a weight issue, but its just a thought.. at least doing it that way would eliminate any chance of it racking...

ok, question, 2 tracks per side? im guessing thats so you have rollers on top and on bottom.. well thats a thought, but i was thinking more like 1 track per side, and then just have a flat "follower" wheel under the rail... maby on a spring loaded arm with some really stiff springs, and some form of adjustable mechanical limiting...
i'll draw up what im thinking later on....

ok, so this is the first time im going to try and attach images... so i put the web address where they are, and also i inserted the images... forgive me if it dosent work correctly.. and there are larger images on the website as well...

http://www.jpcustomcrafts.com/shopmachines.htm
http://www.jpcustomcrafts.com/shopmachines/4x8_gantry_router_perspective_small.jpg http://www.jpcustomcrafts.com/shopmachines/x-y_gantry_perspective_small.jpg http://www.jpcustomcrafts.com/shopmachines/x-y_gantry_perspective2_small.jpg http://www.jpcustomcrafts.com/shopmachines/x-y_gantry_perspective3_small.jpg http://www.jpcustomcrafts.com/shopmachines/x-y_gantry_perspective4_small.jpg

oops... wrong button

Hey,

I somewhat successfully used those V-bearings on angle iron, so did Benny (Ynneb). It is on my third machine, first being a JGRO, second was a torsion box – skate bearing machine. It works quite well and is a magnitude cheaper than using the proper rails. My machine is a 24” X 48” and mostly wood. If you can figure out how to support the angle iron for the length you have in mind, you might want to give it a thought. You can see my build at:
http://www.cnczone.com/forums/showthread.php?t=15270

You can see Benny’s larger metal machine at:
http://www.cnczone.com/forums/showthread.php?t=6143

My recommendations: start a bit smaller until you get the hang of this. Large machines are a PITA to build and costs get large very quickly. You can always build a second machine and re-use many of the components. Chain drive seems scary to me (too loose).

Steve

yea i hear ya, actually after pricing some of the parts that im looking at using, i'm really thinking about cutting this thing in half.. it would be cheaper, take up less room in the shop, and would let me see if i'm really gonna use it as much as i think that i am.. im thinking about actually building it to work a 4x4 or half sheet... my buddy/boss, has a tiny unit that we've been trying to get to work, but theres no communication from his parallel port, so im gonna take the machine that im planning to use over to his place and see what happens....

one of the things that i first noticed about your machine is that you used the angle on its edge.. thats not something that had thought about... i had been planning to put it down open side against the 2x2 frame and spot welding it into place, the one thing that really scares me about that is that theres not adjustability and the other thing is that im afraid that the welding might cause the angle to pull and not be straight... bolting it down like you guys did would allow some adjustability, and i really like that....

the v grove bearings just dont appeal to me... im going to machine my own wheels and then use standard issue bearings, that way i can change out any one part of any one truck if it wears or gets damaged... plus its an excuse to be out in the shop and on my lathe... which in and of itself is a great joy for me...

:banana: :wee: ok, so it might be a mistake, but i did it anyway, i ordered my electronics for to build the drivers, l297's and l298's and some diodes... and then just now i ordered my motors.. i got 3 nema 23 500oz-in 4 wire bipolars for $175... so how'd i do??

the way i figure it, ill spend the weekend building the driver boards, then early next week the motors will get here from california and i can test both them and the drivers... pluss then i can see what the no load speed of the motors is, and that will give me some kind of an idea as to what i need as for the rest of the drive train...

I did have this thought... what if i mount one of the motors onto something solid, and then mount a large set of fan blades.. i know theres not really a way to measure the amount of load, but it would allow me to see how much the rpm's fall off and or if it starts cogging, and give me some idea as to what kind of ramp up to play with.... Ideas? suggestions?? :banana: :wee:

Try to float the pinion on the rack with spring loaded cam system. Works quiet well (will draw rhino example if requested). Typical effective stepper speeds is about 500rpm so calc gearing firstly, pulleys etc can get in the way of construction. Rigidity is essential. Weight also helps on fame etc, gantry should be light and ridgit. Belt an "y" axis works well. For 3d application keep "z" axis accurate, rolled ball screw with good linea and coupling. Do 1 thing at a time. Build one drive test it on cheap motor. Clamp motor to avoid resonance. Apply a little load to that motor ie flywheel or a bit of resistance. Good thing to build 3d model in rhino solid egde etc, helps with spacing and avoids bolting and assembly issues. Build one example of linea bearing, test it on small profile, get it smooth but ridgit. Avoid welding long flexable pieces of steel, try precision dowel and bolts. Watch for swarf and debris on crucial mechanical parts. etc, etc, etc

yes, if you will please draw me an example of that one, im just not getting it in my head...

ok, 500rpm, i can definately work with that....

i was worried about using a long belt, having no experience with them, i was worried about it being kinda springy, and giving and stretching under load and with sudden accel's and stops....

clamp the motor??? you mean to the frame with a c clamp? or are you talking limiting the current?

my rails will be above the table, so im hoping that will reduce the amount of chips, and im planning to make some little brooms that will clear the rails as the axis move...

im considering lots of options for the x axis drive, possably dual x motors and screws, or maby rack and pinion.. or maby even a crossed chain design... im just not sure yet... the other idea that i had was to run the x screw under the table... mount the x motor on the gantry and spin the heck outta the nut.. i have a couple of ideas on how to do this... my thinking is that this way i wont have to use as large of a screw to reduce whipping.. i'll only be worried about the push and pull forces... plus by having a stationary x screw i eliminate the end play of the screw...

the other off the wall idea that i just came up with and its cheaper than all the rest of the ideas ive had, was to have a length of 1" wide .5" pitch drive belt along each of the side rails.. then do the upside down u drive thing with the belt. By pulling the belt tight at each end, im creading a flexable rack... The belt should have little to no slop in it, and thus is better than the chain, and is also going to be lots quieter than the chain.. then just have a shaft that connects the 2 sides together and have the x axis drive motor mounted on the gantry.. again i know this adds weight. the point of this is to not have to have closed loops of belts.. but just use the cheap easy to measure for open ended stuff... i'll try and draw some of this up tonight when i get home... but this is sounding like the way to go...

another idea that i've been toying with is for my power supply, im thinking that i really want something in the 36-48 v range, so i was just wondering, about atx power supplies, i saw somewhere else on here someone was thinking about this.. but im going to wire it just a little differently.. im only going to use the ground and +12 lines.. what i need to find out is if the ground is common to the chassis of the power supply, or if its more like the CT on a transformer.. if its an "open" or floating ground, then im in good shape, i can series 3 or 4 ATX's together to get the 36-48v.. the question is going to be the current.. well i have someone willing to donate 4 computers for parts to this project, so maby i'll pull one of the PS's out and play with it, its the right price so that if i smoke it im not out... and yes i know i need a "load" resistor on each PS so that the switcher is happy... i just need to figure out how much load, and if i need one for each V out, or if one on any one of the v outs will work...

http://www.cnczone.com/forums/showthread.php?t=17548

o i c so i do have to find the chassis ground and dissconnect it.. ok, good information.. i gotta go get thoes machines and rip out the psu's and set it up.. if nothing else for the experience.. and maby some fireworks, and then just maby maby something useable.. maby for the cnc, maby for just a test bench power supply... spiffy...

Hello p5k.

lets take it one step at a time. There is a lot of litrature on stepper motors, some of the most accurate is from Marais at geko drives. He has a short sysnopsis or document explaining the relationship between power/current/voltage etc of these motors, it is definately worth a read.

Without getting very tech about this here are a few generalisations:

Steppers act almost inversly to a dc brush motor in that they have unique power to voltage curves etc. for example more volts can produce more torque but not neccisarly more speed.

A rule of thumb would be to start out with 20 to 25 times rated voltage, but reduced current to the motor, heat is a good indicator as to wheather the motors are running near there capabilities. Hot to the touch but not excessive. If you can hold the motor for say 10 seconds it probally is running well. This sounds kinda strange and not very scientific however there is a lot to these little devices. Increasing the current will generate more heat, vica versa. Resonance is a small issue as well, at certain speeds and a certain current these motors can produce sporadic results also depending on the load they are trying to drive. It is always good to have some load on the motors do dissapate energy that can return to your driver. It may reduce resonance as well, free running motors are not a true indication.

A lot of steppers availabe produce good power/speed results at about 500 to 700 rpm. This brings me to gearing.

You would be surprised at how accurate a shop built machine can be for say cutting mdf, ply etc with a reduction ratio that translates to:

// I hope my math is correct, we deal in metric units over here. I know my spelling sucks. //

lets say 100 full steps to 1/2 inches (approx 6.35mm) of travel, yielding quit a good speed with resonable accurace, however you can micro step these motors ten fold producing very respectable speed and accurace, however the step output frequency from your parralell port will also increase.(there are limits to the parallel output normally/reliably around 20k.)

ie a 1.8 degree stepper has 200 FULL steps per rev. therefore 600rpm translates to 120000 steps per minute or 2000 steps in a sec.

or at 200 steps per inch producing speeds of up to 10ips (10 inches per sec or 250mm odd per sec) and microstepped will give ya accuracy of 2000 steps per inch. remembering your pc output or driver might only allow 20k on the limit in this case.

With this resolution in mind, i have had no trouble with with using a reinforeced belt driving a 2metre y axis or 6 foot axis with less play than the capable resolution of a stepper.(especially with the drift between its holding points)

as far as the x axis goes, i highly recomend rack and pinion. Firstly its cheap, strong easy to assemble (will send drawing of floating mount) yields great accuracy.

As far as power goes, motors of most sorts like simply regulated supplies , ie a torrodial with reg and caps, maybe a resistor to draing cap. Over here they are pretty cheap ie 400va 36v ac torroid is about 30usd. Switched mode supplies can produce odd results, but i am no expert in this fiels.

ok, thats some good guidance... thanks.. well the drivers that im building can handle up to 46V so im going to aim for about 40 for now.. and then i can allways build bigger and better drivers later on.. or buy some, whichever the case may be.. but for now thats a decision i made, and so im going to live with it.. cause the parts are here, and i actually have one of the drivers breadboarded up and working some led's with the demo of mach3...
i cant add the video here, so heres a link...forgive the yellow snail.. i was trying out some new free software...
http://www.jpcustomcrafts.com/shopmachines/Video_09.avi

oh and i did some more drawing, this time showing the long belt mech, x axis drive motor, and cross table timing shaft.. i noticed several things when drawing this, so theres gonna be some redesign... first thing that i dont like is the thought of 6 feet of unsupported spinning shaft, so i'll probably but some sort of bearing block in the middle of the x slider... secondly for the 5:1 gearing i noticed that the pully is going to be in the way of the y and z axis when its at one end of the travel.. so i'll have to come up with something, maby a jackshaft arangement, depending on how much slack there is in the belts and pullies...

i arranged the belt with the "teeth" downward so that they wouldnt collect swarf and or dust... and the 2 lower pullies are to guide the belt and to maintain a higher % around the drive pully in contact with the belt..... lemme know what ya'll think..

Two motors on the x axis seems far more appealing than that cross link shaft. You said you may want to router with this machine, but i do not understand how you plan to overcome the force applied by the router on the material against the lift of your cross travel slide. Those belts will have to be tensioned quiet correctly (not a big deal) but may lead to some drift. You could always re-calibrate mach. Those gearing units will have to be well secured to the gantry. Why not rack and pinion? (I dont really mind that belt idea, it will cut fairly accurately).

Another thing, I believe that cheaper rack is cut with better tolorance than belt tooth spacing. But i cant confirm this, mabe a good idea to look into it.

while i would agree that the potential for accuracy with the rack is higher, from what i'v found on varous sties, the rack is still quite expensive... i can get enough 1" belt to do the 2 x spans, and have one for the Y for around $100.. the cheapest rack i have found was closer to $250...

also, in post #18, the 3rd pic, you see what might look like a bolt going through the frame and to the belt.. this is just a representation of a method that i came up with to tension the belt.. i understhand that he belt will need to be under some tension, one to overcome the sag that it will have, and the other to position it correctly...my plan was to have a tensioner at each end of the belt, so that i could shift the belt some one way or the other to get all the "teeth" to line up from one belt to the other...

as for the lifting force that will be created by the router.. i do have a solution for this, but i didnt have time the other night when i posted thoes pics to draw it in.. I'll try and work on this tonight and post the pictures of the pinch rollers, or hold down rollers as it were...

ok, here's a couple sketches of what im thinking for the anti lift rollers.. basically its a pivioting arm with a bearing on the end.. this bearing will ride on the underside of the horozontal frame member that the angle iron is attached to on the top.. this will effectivly pinch the rail with bearings... the one thing that i have incorperated is a spring loaded mech... i have lots of chevy valve springs laying around, so i was thinking that if i were to use one of these, i could tighten or loosen the bolt to set the tension on the pinch...but this would still allow it to flex a bit if there are any inconsistancies on the bottom of the frame.. i think that a valve spring would be plenty stiff enough, and if its not then i could fill it it with some solid rubber, or maby even a eurothane bushing...

so i got home this evening and found a box on my front step.... Hey this is heavy!! this has gotta be my 3 new 500oz*in motors!!!
so i picked up the box... oh crap, its dented, and scratched, and rattles.. this cant be good....
i opened it up and the inside looked like an egg that had been through a blender... Now, i dont blame the shipper, i blame the men in brown... here are a couple of the pics, and there are are more at http://www.jpcustomcrafts.com/badshipping.htm
all 3 motors have rubs and scratches on them
one has its wires cut off
and the worst one has a massive dent in the caseing and i cant even turn the shaft with a pair of pliers!!!!
i sent my shipper an email, so we'll see what happens from here...

ok, a little update.. i emailed with my motor seller, hes expediting new ones to me and then we'll deal with the men in brown... so thats way cool of them...

also, i have ordered some parts... i got 4 screws from ebay, a 72" a 36" a 12" and a 9".. i got the 12 and 9 cause i havent decided how much throw i really want/need on the z.. i figured for 10 bucks, eh why not have the choice laying here... oh, and i also ordered my screw bearing blocks... so we'll see how all this starts comming together... since my screws are all 1/2"-10, im seriously considering spinning the nut on the 72" screw, to help reduce the possibility of having it whipping around.. according to the graphs i have found you dont wanna spin a 1/2" screw faster than about 400rpm at that length, and depending on how things work out, i may need and or want to go faster than 40IPM... now that the machine is truelly scaled down and i've committed to this new smaller size (yea i know some of yall think its still too big for a first machine) i need to go and get some steel and get to welding...

Hhehe.. I thought spinning the nut was a good idea to but then you compound the cost of the carrier bearings (if you built one similar to the Jeff plans like the spinning nut of my Z) you will set your self back nearly 100 bucks just for those bearings..

Then figure the motor's weight will be spinning down the length of your support (ie for my 4x8 that would mean another 10lbs out on the gantry moving back and forth)

Course the first reason (big time expencive bearings to make a spinning nut configuration) was why I didn't do it.. Course also if you don't dream up using iron pipe and try to turn aluminum for the nut holder (and you are a NOVIS at the lathe (ie just purchased it for this/these projects)) you would have wished you went with rotating the screw..

Anyway my design has a 60" long .631 diameter screw. I'm preloading it on both sides with angular contact bearings so that will hopefully buy me a few more useiable RPM..

b.

yea, your screw is both bigger and shorter than mine.. and i cant even begin to imagine a couple bearings for this costing any where near 100... i figure it more like this... 10 for a pair of caged thrust bearings.. then maby 20 for a pair of axial high speed bearings, and some alum stock that i already have, a little time at the lathe (which ive had for years and have made some pretty nice rc car clutch parts) call it maby 50, and i should be able to more than double the rpm that i can use... but here's the rub on it all... once i get out there and actually start peicing it together i may have one of thoes "what was i thinking" moments, spin the screw, and be done with it... hehehe i bought bearing blocks to spin the screw, but it was just one of thoes, hmm i wonder if it'll work kinda deals...

plus my motor weighs something like 3lbs 10 oz, so its not as heavy as yours... i was just sitting here thinking, if i spin the nut, i should be able to get faster accelerations just cause im not havving to start spinning the mass of the screw... i guess i'll just start off spinning the screw and see what i can do with my gearing and what kind of top speed i can get.. theoretically i could spin it at 400 rpm, or thats the max that my chart shows.. so thats 40IPM, and on a 72" machine, that seems a bit slow to me... but it wont matter cause im not gonna be cutting at that speed, that'll just be my rapids.. and if im doing a jog or something, then i'll have the software limit the speed.. so who knows, it might be good enough for who its for :D

Ya I'm wondering about my rapids but more worried about it as my machine gains more and more weight as I build, weld more stuff on, and more stuff on and more stuff on.

Saw that video of the Carvewright machine, Nice small light weight and the head can zip around quick. Got me wondering after I'm done with this one I will maybe think the other direction ie: light weight Small FAST!!!

Course who knows. With the 1100oz al hugo motors I suppose I should be able to toss this weight around pretty good.. Seems to be able to lift my (probably over weight 10.5" travel Z on a 7volt cordless drill motor pretty easy) It should fly (hopefully not crush limit switches in the process) on 30-40 volts I'd say..hehe

b.

after our chats ive been meaning to check out your setup thats a pretty good looking design, they only question that i have is with the belt drive setup , i notice the way the belt runs thru the pulleys at 90 deg angles ,do you think that once the belt is tight , the drive motor will have to put any additional effort to pulling the belt up aruond the pulleys ?

also thats sick bout the motors , UPS SUCKS ! they charge an arm and a leg for shipping , for what ? , at least the sales guy was decent

im sure that having that aggressive of a bend in the belt will add some resistance to movement. after i drew that up, i began considering moving the idlers apart from each other reducing the angles involved, this would allow the belt to live longer, and would reduce some of this drag, but my original concern, and why i drew it at 90deg, was to have as much belt to pully contact as possable, as i was hoping to use at most a 1" diameter pulley.

i actually came up with a different even crazier scheme last night in a dream, but i just cant see it working, cause it causes the belt to flex in all 3 axis.. maby i'll draw it up and post it for giggles..

but unfortunately what everyone said would happen has happened... the cost of building a machine that large was more than my budjet could handle, so the full sheet machine has been back burrnered for the time being, i'll probably keep drawing on it some, so if and or when the time comes i'll have a plan..

Yea i was really upset to see thoes nice new motors get trashed.. and im sure when the ups man comes tomarrow to take a look at the packaging he'll take em and they will just trash them after all... its really very upsetting.. but my seller has been totally awesome, good clear fast emails, totally cool about working with me to get me what i ordered as fast as possable considering.... i have been very carefull not to mention my sellers name as of yet, just to make sure that everything works out in the end, but if the motors show up tomarrow, and their in good shape, then he will have totally honored his end of the deal, and more... i have to say that i was realy surprised when he told me that he would ship the new ones even before ups had seen the old packaging, and he hadn't been re'embursed yet.. I guess the bottom line is that i got really lucky, and if i need more motors in the future, i will definately go to him first... prices seem reasonable to me, shipping is darn fast, he sends tracking #'s so i can track my toys, and then when theres a problem, pronto fixo!

theoretically i could spin it at 400 rpm, or thats the max that my chart shows.. so thats 40IPM, and on a 72" machine, that seems a bit slow to me... but it wont matter cause im not gonna be cutting at that speed, that'll just be my rapids.. and if im doing a jog or something, then i'll have the software limit the speed.. so who knows, it might be good enough for who its for :D

I think you're going to find that when cutting wood, 40ipm will be painfully slow for cutting, and approaching torture for rapid moves. Imagine pushing the start button and having to wait almost 2 minutes to get to the other side of the table to start cutting. :eek: On the plus side, I doubt you'd have to slow it down to cut, as you should have plenty of power at that 40ipm.

thats true, and thats only when im working large peices, with the 10tpi screw i figure that even if i gear from the motor 1:2 the screw will spin as fast as it should, and i still get .0005" increments, thats accurate enough for any pcb's that i need to make, and it will be great for most of the things that i want to make, on the odd chance that i do have a part thats 72" long, so be it, it'll take a while, theres plenty of other things that i could be doing out in my shop, sweeping, building a new workbench, finishing my mother-in-law's van, repainting my trike, whatever.. lots to do, so i can star that and walk off from it.. and just poke my head back to it once in a while just to smell if theres any smoke :D

speaking of my trike, just to give ya'll an example of my wild and crazy ideas...

Look Out World, I'm A Man With A Welder And An Imagination!!!!

wanna see somethng beautifull, look what just showed up at my front door!!!
screws, bearing blocks, nuts OH MY!!!

thats a 9" a 12" a 36" and a 72" all 1/2-10
its time to start cutting some steel... i think for my first machine i'll scale everything down to a 36"x12"x9.. that seems managable, and will do 90% of everything that i want to do.. then if i ever decide to go bigger i have that longer screw...or maby i'll sell it to buy some more parts for this machine, dunno yet....

ok, so i drew this up with the new dimentions.. it has a usable area of 36x12x9(thats the big block in the first picture) uses 1530 for the frame, and then has 1515 inside that for the table structure.. my thinking was to use a peice of MDF on top of the table frame to make a solid deck to put parts on and so forth... what do yall think? will it be strong? will it flex too much? what am i missing?

the gantry uprights are 16" in this picture.. and are made of 2 1530's bolted to gether somehow....

i was thinking that i would use the machine once its up and running to cut a pocket into the mdf, say .125" deep the full size of the usable area, and then inside that make a grid something like 1"x1" for alignment purposes.. this shouldnt weaken the mdf too much will it? my thinking was that this would just make using the thing easier each time i go to setup a job........

anyone?? also, i was wondering, whats the average amount that the linear slides should be longer than the travel length... what i mean is if my screw is 36" of usable travel, the should that axs' linear slides be something like 48"???

i was thinking that if i mount the linear bearings about 6" apart then that would help with some stability, i know mounting them farther apart would be more stable, but if i go with something like the nsk ls15's what kind of weight will these carry? i have absolutely zero experience with them, so im hoping someone can tell me a little about these buggers before i have to just go out and get some and try them out for myself... just hoping that they will work....

well since no one answered my ???? i have just made a decision to try it... so i went out to the shop, scrounged some left over steel, and went to work.. this is what i have so far.... not much, but its a start... the main rails are 3x3 11ga box, and the legs are 1x2 11ga.. i put a dial indicator on it and got about .010" flex in the middle with my hefty 230lbs right in the middle,, i figure the gantry will probably weigh something like 50, spread across both main beams and with the skate bearings 18" apart, so i'm pretty happy with the rigidity of it....

since there is no rib in diagonal of any square produced by the ones you have placed on your bed there is no way of prohibiting the bed to twist under right circumstances
mdf as spoilboard would be nice, but even nicer would be steel plate and then mdf spoilboard bed
as for the screws and sliders
they seems to be standard trapezium screw with single nut - how do you want to solve backlash problem?
the lenght of linear sliders depends on mounting spread for nut - you have one in your initial setup so thus you've drawn conclusions that they should be longer than the screw
but then again, why you add 12 inches? you had 6" spread, so it will move only +-3" futher than the screw lenght (and this is only when nut has 0 lenght)

so i've made some more progress on my machine, and yes ive actually started making something... i've decided on 3x3 working area, i think that will be big enough to keep me busy for quite some time, and theres no reason that i cant also do small stuff on here too.. my plan is to set this up as a router first, and then think about making it convertable to a plasma table, as i have need for both.... so heres what i got done today...

i started off with mateing the 2 side rails together, making sure that they are true square level and even.. and then i started in on the sliders.. just going with the bearings riding on the upturned 3x3 box... started off with just 3 bearings, and realized that this wasnt stable, so i added a 4th and now im much happier... hopefully in the next day or 2 i can start on the actuall gantry... if, once i see that there is a need, i will add a capture bearing under the 3x3 so that the gantry cant lift.. but for now im gonna just try this and see...

the other thought that i had was to mount the z axis sideways, meaning that rather having the linear guides for the z inline with the y axis travel, i would mount them inline with the x axis travel.. i was just thinking that this would be a little easier from a construction standpoint... but i guess we'll see what happens.. has anyone else done this? what can you see as the pro's and cons of this?

Will the Z straddle the gantry, with one rail on each side? Some machines have a wide gantry, with the z-axis in the center of the gantry.

It looks like you’re off to a good start. Square tubing rails should be fine for a woodworking machine as long as they are strait and not twisted to start with. I would worry about them twisting in the future though. I have a habit of over-engineering things but you may wont to consider filling the tubing with sand and epoxy. This is done quite often with X2 Chinese mills. It drastically increases the stiffness and mass, which dampens vibration and makes them highly resistant to twisting. I would not do this to the moving parts, but would strongly consider doing it to the frame.

I did a quick search but didn’t immediately find anything on the Internet about doing this, but I’ll give you a quick summary from memory. The idea is to fill a tube or column with dry sand then dump epoxy down it into the sand. When the epoxy hardens the sand is solid like cement, but does not shrink when drying like cement, so it stays bonded to the tubing walls. Epoxy also has similar thermo-expansion characteristics as most metals I think.

The other advantage of a heavy base is that your machine will not vibrate across the shop like my mill does. When it came time to make my lathe bench I learned my lesson and anchored the hold down bolts into 150lb of concrete. A 3” thick concrete table top with a steel plate over it makes an awesome bench, just don’t skimp on the rebar.

Engineers have proposed the idea of the military making unsinkable ships out of frozen saw dust. :banana:

It may be worth some a few bucks to experiment. :cheers:
pxsi

i had been considering filling the rails with something, one person suggested mixing a slurrey of eposy and sawdust, or sand or something, aor eve peagravel... i suggested lead shot so it would act like a deadblow hammer... there are several ideas... the other idea that a buddy of mine came up with was to mix sand or peagravel and 2 part foam... it was an interesting story to hear him tell anyway...

as of right now the 3x3 steel tubing is stiff, straight, and dosent have a single wave in it... i can stand on it and not get more than about .010 deflection on one rail, and i way 235.. so if i were to split my weight across the 2 then that would be .005 and i know my gantry wont weigh half what i do, so thats .0025... all of this was with me standing on 1 foot right in the middle, and my gantry has 2' long sliders, so that spreads the weight out... im really planning on doing some aluminum on this machine, and possably even setting the plasma cutter or oxy torch on it... i know that plasma takes torch height control and all of that, also faster feed speeds, but that is all something that i can investigate later on once i have the thing running and making some $$ with the wood.. i already have orders for stuff, but the delivery date is dec 1, so i still have some time to get it up and running...

right now im really trying to figure out what im going to use for a spindle, im thinking maby a porter cable router, it takes 1/2" and 1/4" and im sure i can find andor make some adapters for smaller... 1-3/4hp will probably be all i need for wood, and maby even the aluminum... its that or a trim router, thats something in the neighborhood of 1hp,, im just not sure if thats gonna be enough tho... im really planning on getting some 3"x3'x3' chunks of wood and doing some really nifty 3d carvings with this thing... i have the artwork done, i just need the machine....

i'm probably going to spin my lead screws for now, but once i get that going, im going to play with some spinning nut systems, i think i can get more speed out of that....and with the way that im thinking about doing it, the backlash adjustment wont be a problem like it is in some other designs i've seen...


also, the table will weigh a good deal once done, and this weight added to the frame will help with vibs, and all, plus the plan is to bolt this thing down to the floor once its done... im just gonna use some redheads like what i did to hold down the compressor... cause that sucker would just walk all over the place...

well i spent some time this afternoon out in the shop workn on the router... i have the gantry welded together, and the bed... i originally thought about just having the bed supports running across the bed, then it dawned on me.. "hey dummy, thats not gonna keep it from going dimond on you" so i changed up the bed bars so that they make triangles... now that sucker outta be good and strong...

so i spent some time out in the shop today, and build up the basic frame for the y axis, its just tacked together for now.. but i had to see how my idea would work... this just as the x will need to have "hold down" bearings installed.. but this is progress anyway....

hope you like my doggie slippers hehehe geez i didnt realize thoes would show up...

oh and i almost forgot, i picked up 6 of these disco'd cpu heatsinks for my home built driver boards... im running 2 l298's on each axis... i figure i'll drill and tap the bottom plate of each one, and it should be ehough heat dissapation...

Just a word of caution
cutting wood and metal in the same shop is a fire wating to happen.
I run a cabinet shop and sawdust hides everywhere, a spark can smolder for hours and then flame up long after you leave the shop. So you might want to think twice about a dual purpose machine.

onthemarc

thats a good point, and is still true even considering a cyclone dust collector for use when doing wood.... but considering my shop layout, and my do-dilligence of cleaning up... and the building and floor are non combustable, even if there were a small pile of dust under one of the legs fo the machine and it flaired up, there wouldnt be enough fuel to sustain a fire long enough or large enough to do any damage... but its definately something to think about.... one thought that i have is that i also have a 20x25 barn thats just got junk in it, i was thinking about putting this machine in there and using that as the wood working shop, and then building a second machine for metal in the concrete shop.. that would sepperate the 2 quite nicely....

so i've been tinkering the last few days, and made very little progress, but have made some... got my lovejoys from mcmaster carr today, i was impressed with the speed of shipping... ground, ordered monday, here wed.... so i went out and tinkered with the yaxis screw and motor mounts... why did i do the y before the x... well actually just cause it was easier than laying down on the floor every time to mess with it, now that i have the system that im going to use, i can replicate it and only lay down a couple times, rather than the 40 times that it would have taken to first engineer this thing.... i'm thinking that i'll need to add some gussets to my screw and motor mounts to keep the angled parts from flexing, but i'm gonna try it this way and just see how much they do flex and then decide if i need to strengthen it any....... heres a couple pics of where im at now...

For some reason I keep forgetting about your build progress.. (asking for pic's from my other thread..)

Oh well I forget..

One thing I don't see is adjustment on those bearing guides.. Everything in the drive system of mine (bearings and belt tention and rack mesh) all are adjustiable. The v bearings can all slide in the c-channel and have micro adjust screws. The mesh I lasoed the upper bolt of the bearing pillow block with a washer with a piece of threaded rod welded to that then ancored to a plate at the end of that c channel..

Anyway Bearing adjustment is something to think about..
Figure no matter how well your welds are and accurate you layed it out the stuff is so heavy impossiable to get perfect. Becides once ya get the steel shrinkage heating to much for the final weld can toss the tollerances..

Other then that looks interesting.....



b.

b.

your absolutely right, and its something that im working on... there is about .002 gap between one of the bearings and the square tube on the y slider... i'm working on an adjustment for this...

Looks like it's evloved (changed a bit) from the orignal drawings..

Were you still going to do belt drive for the (I think it would be) X?

And the MFD is going to sit on the crosed section of box steel already there?

I'm not looking Forward to doing the table of my machine. Hopefully having the gantry all setup will help the process (ie use the gantry to lay out the table and doing that will hopefully result in a flat table?) That is probably wishfull thinking But the darn thing got to be so dam big I can't think of how hard it would be to assemble if I could not walk right up to the gantry.. The motor sits up over 6' from the ground when Y is fully up..

Anyway looks good. Glad I'm not the only one doing box steel on 45deg..hehe

b.

its definately a work in progress, constantly changing as i see this or that wont work...

no, i've decided that belt was just too much $$ for me right now, so im going with 1/2"-10 screws...

yes the mdf will sit and be attached to the star patern in the table... the plan right now is to cut the mdf so that there is a little gap between the table and the angled box so that there is somewhere for the dust to go rather than pile up and get int he way of the bearings....

the height is one of the reasons that mine is so close to the ground... i can walk up and work on the y and z axis' at a comfortable height... plus i figured that most of my stock will probably be on the floor or a small cart, it will be easier to load it onto the machine with it low, rather than at say waist height.. i can allways raise it up on taller legs or buld a table kinda thing for it to sit on, but for right now im planning on just welding tabs on the feet and using some redheads to bolt it to the floor....

getting that table frame flat and level was a job!!, but i just took my time, used some ratchet straps, jack stands, and lots and lots of measurements with tape measures, and about 5 different levels, (making sure to turn the level around each time to make sure it read the same both ways) untill everything was all right where it needed to be, put a small tack weld on each end, repeat measurements, another tack, measure, tack and so on.... its all welded together with probably thousands or little tacks... i figured, it might not be as strong this way, but my heat effect zone is much smaller, its easier to fix by cutting a tack weld than cutting a long bead, and the smaller welds dont pull and distort things as bad.... might be right, might be wrong, but its what i did.....

aaa ratchit straps.. Going to have to remember that one..

Was wondering how I'd clamp things together..

Most of my height was governed by those blue legs I got from work. They are like 1/4" thick steel rectangle with the welded on flanges (figured I'd leave them on till I figured they would not do me any good).. But since they were all cut to exact length to being with and I'd have a hell of a time cutting them with my abrasive cutter and they would never be as accurate I'd stick with that height.

course building on my bamsement floor is probably more a problem since it's not as level as it should be for a job like this. + I'm planning on moving the machine after built to it's final resting place... So got some things working against me..

Yep small welds with gaps rather then a complete beads. more complex welding tech's are best left to the experts..

My first rail turned into a question mark because I overheated it... The second 2 came out great though (ie Learned something)

b.


b.

hheehe yea, it was asking what were you thinking??

for the ratchet straps, you can get some really cheap ones at walmart or harborfreight.. i wouldnt use em to tie much down, but there great for holding this and that while your welding... just watch out cause welders have a tendancy to melt the straps...

if the legs you have are all straight and square, then i wouldnt mess with them either... at least not till i had to....

i'm building on my shop floor, but its dead flat and super smoothe.. when i poured the slab i made dang sure that the forms were perfect, and when we floated it, i kept a super tight string handy... over the whole floor, theres maby at most 1/8" deviation, and thats in 60 feet....so i'm pretty happy...

in the evenings when i get home from work, i mostly just read on the computer and play with demo versions of software.. one thing that i ran into last night was when i was playing with the vcarvz demo, and i would try and then import into mach3 i would only get about 6 or 8 lines of information, and none of it was really move commands... even tho i know that the code to do what i drew woulda taken a couple thousands lines... anyone got any ideas on this?
is there a sure fire way to do from vcarvz to mach3? i tried saving the text, but looking at it, it didnt look like any other gcode that i've ever seen.. i'm wondering if mach is choking on it and just not displaying it... i really like the vcarvz software from what i've seen thus far with the demo, but does anyone else have something that they use thats reasonably priced? i'm just looking at the software costs, mach is about 160, and meshcam is about the same, and i didnt even look at the vcarvz price yet... but i would imagine its prolly about the same as well, so thats 450 just for software... ideas? suggestions?

Like your work, whish I was a welder, only thing around here is saw dust.

I was looking at your last photo and I see you have bearings on top and the side but don't see any to prevent it from lifting. If it is only a plasma cutter it is not an issue, but if you are using a router it must be prevented from having the router push it's self up when it is driving down.

Again it it's only Plasma, forget it.

Keep the pictures coming. :rainfro:

as stated in previous posts, i plan to add under rollers later once i get it moving, my plan is to use valve springs to "preload" the rollers to the underside... this will stop any lifting that my system will generate, and if it dosent, well then i'll double up or somehting...

in the evenings when i get home from work, i mostly just read on the computer and play with demo versions of software.. one thing that i ran into last night was when i was playing with the vcarvz demo, and i would try and then import into mach3 i would only get about 6 or 8 lines of information, and none of it was really move commands... even tho i know that the code to do what i drew woulda taken a couple thousands lines... anyone got any ideas on this?
is there a sure fire way to do from vcarvz to mach3? i tried saving the text, but looking at it, it didnt look like any other gcode that i've ever seen.. i'm wondering if mach is choking on it and just not displaying it... i really like the vcarvz software from what i've seen thus far with the demo, but does anyone else have something that they use thats reasonably priced? i'm just looking at the software costs, mach is about 160, and meshcam is about the same, and i didnt even look at the vcarvz price yet... but i would imagine its prolly about the same as well, so thats 450 just for software... ideas? suggestions?


Sounds like a VCarve issue. Ask in the Vcarve forum, they should get back to you very quickly. Btw, VCarve is $500. :(

hmmm sounds like thats something to save up for by using meshcam for now, make a few bucks, and then buy the vcarvz...

Hi Project5k,

Are you running the Free Trial version of VCarve Pro (http://www.vectric.com/WebSite/Vectric/products/download.htm)or vcarvz?

VCarve Pro has a specific Mach3 postprocessor but I think vcarvz only saves standard gcode.

The Trial version of VCPro lets you save the toolpaths for sample files, so you can cut these designs on your own machine. The video tutorials and documentation (http://www.vectric.com/WebSite/Vectric/support/support_vcw_tutorials.htm)can all be downloaded from the web site.



The price of VCarve Pro is $495 (thanks Ger21)

I hope this helps,

Tony

Thanks for catching the vcarvz thing Tony, I missed that.

i didnt know there was a difference, good point, i'll have to lurk the web tonight and find the pro demo and give that a shot... but thats still kinda pricey, so i'll have to wait untill i get my meshcam and the rest of the machine up and running, make some parts, pocket some cash, and save up for the pro..... thanks for the heads up on that.. i totally missed it...

So while i'm waiting, i decided to use some other materials that i had laying around and build myself a media blast cabinet... i still have to add a light inside, and i think i've decided to make the window bigger... also need to add the bottom shelf on the cart and some bracing.... then add the weather stripping around the door, a latch on the door, add the grate (expanded metal) inside, and some plumbing for the air supply... then bingo.. i'm considering adding a dust extraction port, but i can add that later after i see just how dusty alum oxide is... ive never used it, so i just dont know yet.... not too bad for about 4 hours work out in the shop, and just using materials that i had laying around...

(wrong) ok so i know this isnt really cnc related, but i thought yall might be like me, and want to have a place where you can safely media blast, so i thought i would share this. so if you ever wondered, you could see how i chose to do mine...

well I started soldering up the first prototype of my home built driver boards tonight... im not done, but its late and this is what i have so far...
a few things that i have noticed, the traces need to be wider... so for this first version, im just solder stacking all the power traces, so that they dont light up like a light bulb....

Hey, Thoes are impressive boards.

Hager

thank you... my boss at work is also into cnc, and he offered to photo etch the boards for me... we have a few design issues to work on for the next version, but for my use, if it works, then thats good enough... he's talking about wanting to mass produce them and sell them, but i dont know how serious he is about it...

WHOOOOPIE!!!! it works..... so i fiddled with it some more this evening and actually got it up and running.... i know it looks like scrambled eggs right now, but i was using the parts that i have handy, i'll get better resistors later, but i had to prove the design and pairing up the 2 L298's first....
ok, so help me out, a stepper should run warm, yes? but not too hot... well after playing with it on the desk for about 10-15 min, i got it up to about 110F, the pic was taken after a couple min of it being off... man i gotta love my lazer thermometer....
so let me see if i understand the why... in a regular commutator motor, under no load it turns the fastest, and draws the least current, and thus stays relatively cool, but when loaded, the current goes up, rpm's go down, and temp comes up...
But in a stepper, running or not, theoretically speaking, and using a chopper driver... it should have about the same current going through it at all times, (not accounting for field charge time, and not counting for half step vs full step and having 1 or 2 windings energized) so theoretically a stepper should get warm weather its running or stopped, and loaded or unloaded?

well, i guess its time to get to work on my powersupply, something tells me that the 24v im using right now just isnt gonna cut it....

oh and i almost forgot.. i paid for my energy chain on ebay today.. got a sweet deal i think... check it out.. got 2 of these chunks....

just copy and paste this into the search on ebay and tell me what you think.. 15 bucks for 46 inches??? seems like a great deal considering i found the same thing on mcmaster carr for more like 45 or so.....

170038965942

Cool..

Although if you had a Harbor freight near buy I would have purchased the blast cabinet..

I use mine way less (ya can see it in my pictures) then I thought I would..

The driver boards look impresive. I do a lot of circuit design for my timing systems... With all my equipment I've never etched or cnc's a custom board (still use radioshack bread boards for the design) If you use your imagination you can design a pretty efficient setup using those boards.

But would be cool some day to spend the time and etch a real one..

The chain was a cool find. Ebay has become the first place I look for most stuff. I think I have a few feet still left over out of what I used. Scoring it free from the plant worked out good for me..

b,.

yea you luckey dog.. where i work, your not allowed to take anything, and they dont throw anything away, it all goes into a crusher... and they wont sell anything either... so its just not an option for me... but i feel really good about the price i paid....

we do have a harbor freight.. one in san antonio, and one in austin.. but the cheapest that they had was like 90 bucks, and so far i have spent exactly $0 for mine... and mines bigger.. i can fit a 15" wheel in mine, and you cant do that with the little ones... well at least definately not and still have enough room to really be able to work and manipulate the part like you should...

I've been etching my own boards for years now.. and i get most of my supplies from the cellphoneshack... i could get them cheaper elsewhere, but thier just around the corner, so its faster.... there are forums for homebrew pcb's, lots of good information... you might look 'em up.... so far i have about $70 into my drivers.. thats all the chips, diodes, and parts, and thats for all 4 axis... i just couldnt see spending something like $100 per axis for someone elses stuff when i can build them so much cheaper myself... plus then i can modify the design, and i really know what the limis are of the parts, you buy someone elses' box, and you never really know... except what they tell you.. well... till you let the majic smoke out and find out the hard way...

got my z axis slider in the mail the other day, i'm really happy with it...
the rails are about 12" long and the truck is about 3 long , so that gives me almost 9 inches of travel which is just fine by me...

Those thompson units are the way to go if you can find them for a good price. Nice and super stiff with the center supports..

I had to machine a bit out of my supports to clear everything though..

Now the question. Are the pipes going to slide up and down and the stage be stationary or the other way around?

b.

you know....... that very question is one that i have been pondering for weeks now...... i think i finally convinced myself that mounting the rails, and having the stage move up and down was the way to go just cause it would be less moving mass, less weight on the screw, and thus less wear and friction.... heck i recon ill just hold it up next to the gantry both ways, and see which way loosk like it will be easier to make work.. altho i did slide my z screw through the hole in the stage, and i think with just a little machining i can make that work really nice, and then just drill and tap the stage to accept screws to mount the nut..... just seems easier that way to me... i've actually lost sleep over that question, and just when i thought i had it figured out, you had to go and bring up my doubts again... darn you.. hehehehehe just kidding...

Looks like everything is coming together.

If your steppers get to 110 in a test situation they will most likely get hotter in a production situation. My recommendation is to come up with a cooling system now while you can still get at everything easily.

On my cnc mill I mounted chunk of 3” pvc pipe around my steppers, and put a fan at the end. This made a nice wind tunnel that keeps my steppers cool to the touch. It also makes a nice guard to protect them from damage.

pxsi

well now thats an interesting thought... pipe or something of the like to channel the air movement... but i'll tell ya, at 110F, i'm really not worried about it... we'll see how hot they get when i start working them...then i just might do that...

hehe... So glad I have servos rather then steppers....

Not that I don't have to worry about heat.. But hopefully will not:)

I have not cut enough of anything to know how hot they will get though.. But have run my mill servos for a hour or so in a row and they have not gotten to hot to hold onto. Hopefully I can expect the same performance from these monster motors.. They don't seem overworked jogging around my table at all.



b.

hehe... So glad I have servos rather then steppers....

Not that I don't have to worry about heat.. But hopefully will not:)

I have not cut enough of anything to know how hot they will get though.. But have run my mill servos for a hour or so in a row and they have not gotten to hot to hold onto. Hopefully I can expect the same performance from these monster motors.. They don't seem overworked jogging around my table at all.
b.

I don't know where this whole thing about steppers running hot came from, but I suspect it's a self-perpetuating urban legend! I am running 2 BIG steppers with gecko's full on, 60V@7A for several hrs at a time, and they barely get warm. Many months of use. The baby motor only runs on 60V@4.5A, but it's also happy to the touch.

well it makes sence that a stepper should get a little warm, just due to the constant current that is passing through them, so some warming is to be expected... but from what i've read if you can hold it while its warm, then everything is just fine...

Proj... Made any progress with the mill lately????

I'm hoping to make some first cuts tonight perhaps..

I really want to get Vcarve now.. But $$$

Anywho.

b.

yea i hear ya on the $$, i'm still saving up for mach3 right now... i havent had time the last few days to get out to the shop to work on it... went on vacation over the weekend.. but maby this comming weekend i can knock out a bunch...

Just badgering ya now that I'm pretty much done with mine:) Just have to figure the dust collection out but since I also think I'm going to be moving the machine to a new spot didn't really want to put all that hardware up yet.

Ya.. Mach3 is worth every pennie so far I love it. Little busy screen wise but all the stuff has to be there so in that way the GUI is actually perfect...

Just went throuth the teaching screen and taught my machine how to pre-drill it's mfd table so it can be screwed down..

Was a trip to watch it put the finishing touches on it self..

Now I have to figure out what i'm going to do with the machine..

b.

well you could allways give it to me and start the next one :D hhehhehehe
i'll put it to work...

i was having a thought the other day... and i think i remember something about it on here, so i thought i would post the idea and see if it had been done, or was a good and or bad idea...
my thinking is to use mdf as the solid top for my table.. it will be sacrificial, so that way if i cut through someting else its no biggie... but i was wondering if i could just use the machine to level out that mdf, just take off a couple thousands across the whole working area... this would not only define the work area, but also make sure that its "flat" to the travel of the gantry... this might also be a decent way to check out everything and make sure that im not dropping steps anywhere.... thoughts???

My thought is that most people already do that when they add a new spoilboard:-) Just be prepared that it will take some time. Doing an area of 600 x 900 with a 15mm bit gives a toolpath of around 37m

Try one of these.
http://www.amanatool.com/cncroutingdetails/rc-2257.html

spiffy bits... i'll have to get me one of thoes when i get closer...

I hope to run into a bit like that at the wood show in december.. Course I probably will not be able to wait that long and will end up truing my under board with one of my other bits. Currently I think my largest diameter wood bit is around 1" so that will not be to bad for surfaceing.

Where are some pics of progress Proj?> I just installed my dust collection stuff but holding back on the pics so ya don't feel bad..hehe

Still trying to decide on software stuff as well... That is proving dificult.

b.

sorry i didnt fall off the plannet, just having major computer issues, i'll post more when fixed...