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Jan 07, 2002, 11:06 AM
Registered User

CNC foam cutter...I need some help.

I really want to build one of these machines, and have found a website that can help me but I am clueless when it comes to programming the PIC chip. Here is the link for what I want to build. It won't allow a direct link to the CNC machine so you'll need to click on, "CNC Corner", on the left side of the page to see what I am looking at. Does anyone know how I could get a PIC chip programmed? Or does anyone have links to other homemade machines that would help me some more? And also does anyone here have experience making one that could possibly help me?
Thanks for the help. I really want to see what it takes to get this project moving forward.

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Jan 07, 2002, 06:42 PM
Registered User
Here's a couple other sites to look at.....drool, drool, drool!
(English text is in red)

I built a successful 3 axis CNC router for cutting ribs, bulkheads & misc. sheet parts (foam cutting templates also) and dream about a CNC foam cutter...... ahh, so much cool stuff, so little time (and $$$)!

Good luck!
Milton Dickey
Jan 07, 2002, 10:04 PM
Registered User
Thanks for the reply DICKEYBIRD. I think I have figured out a solution that could cost anywhere from $220 up. Buy a 4-axis setup from here; buy the software for around $30 then make a guide to hold the motors and such. I'm e-mailing around to see what price I can get for just a guide but have yet to get a response. If the price of the guide equals a total of $300 or less with the other stuff I may get it. But if it's substantially higher then I may just be building it from here; or another one that I have a pdf flie of which I could send you if you are interested. Both guides are made from the wood.

Just to let you know in case you decide to do the same.

Jan 08, 2002, 08:30 AM
Registered User
Hi Josh,

Yup, I've seen Dave R's & Muller's sites....the price is definitely right! But, there's a lot of hardware and materials needed to build the machine shown on the Muller site. Don't know if you can get it built within the $300.00 price range you're estimating.

Also, I'd be worried about the little NEMA 17 25 oz. in stepper motors being powerful enough to make it through sharp angle cuts like spar cutouts & such without losing steps (losing steps = ruined part!). The stepper motors on my CNC router have twice that amount of torque and I have to be very careful when programming cutting depths and feed rates to prevent losing steps. The inertia & friction of the various mechanical parts of the foam cutter will probably eat up a lot of the available torque. I'm pretty sure the cutting speed would have to be extremely slow, 2 or 3 I.P.M.....come to think of it, you have to go extremely slow for a smooth cut anyway. It may do fine, go for it!

Good luck and keep us posted on your progress.
Jan 08, 2002, 12:46 PM
Registered User
Thanks again but now I have more questions. When you say that a Lot of hardware and materials are missing to build the machine what are you talking about? Do you mean the computer itself, and the framework for the motors? Or are you talking about other electronics stuff? I have a cutting bow and power source for the bow and also the extra copmuter to make it. And do you honestly think I could get by with the 25 oz. in stepper motors? Or would I need something larger and if so how large?

Oh also I think the motors require a power source correct? I think an extra computer power source works right???

If there are other parts that I am unaware of please tell me I want to get an accurate guesstiamte as to how much it would cost me to get one built instead of starting it then realising it would of been cheaper to just buy and entire setup.

Thanks you so very much for helping me.
Jan 08, 2002, 01:25 PM
Registered User
Ok now I am really thinking about this. So here is another idea.

Buy the driver board and timer from here; $83-$120 depending if I can solder.

Buy four stepper motors from here; 150 oz. in torque nominal up to 250 oz. in torque is supplied with higher voltage. Say $125 total for four including the s/h

Software $30

Then I have the extra computer and I can also get a free computer power supply if that is what is needed? Then figure out how to wire everything together.

Build a machine. Price unknown I'll have to guess if I make it from wood it would be around $35 and upwards to $60 if I find a different "cooler/more professional looking" way to build it.

I just listed all the stuff to see if there's anything else I'm missing.?

$273-$350 price range unless there are other things I would need? Oh yeah I already have the bow and power source for it. But I think I posted that.

Thanks for the help. I am getting excited to see if I CAN make one.
Jan 08, 2002, 02:32 PM
Registered User
Hi Josh,

Not having actually built the machine you are wanting to build, my advice is pretty feeble at best. I didn't mean to send you down the wrong path! My comments about the cost of hardware and supplies were based on a quick look at the "La Rustica" plans on the Muller site (looks like quite a bit of wood, metal square & round stock, threaded rods, bearings, hardware & misc. stuff that all add up) plus my experience in building my router with the seemingly never ending trips to Radio Shack, Home Depot & other supply houses.

I would suggest you contact Dave at HobbyCNC and see if he has some detailed advice or could possibly give you the name of someone who has actually built a 4 axis machine using his components.

Also, I would think that simply installing more powerful stepper motors without making the appropriate changes to his circuit board and power supply would be unsuccessful. Ohms law ain't real forgiving!
Jan 09, 2002, 12:16 AM
Registered User
motorhead's Avatar
I have a CNC foam cutter that I built for less than $400. Unless you are an electronic wiz go with the board from hobby CNC. I am using it with some more powerfull motors. I think they are nema 23. Definately run 400 steps per revolution. I am also using the muller software but I wish it was more flexible. The simplest rig that I have seen was made from 3/4" particle board and drawer slides. The CNC machine will cut slower and will not be as flexible as a feathercut system. You will run into wings that have a big cord or a large taper where it will take 15 min for the cut. It can be more accurate because there will not be any wire drag but there are trade offs.
Jan 09, 2002, 08:01 AM
Registered User
Hi Mike,

Great to hear about your machine! Is it built using the "La Rustica" plans from the french site? Can you post a picture? Sounds like I wasn't too far off about the very slow cutting speed....what speed in I.P.M. do you use? Do you use a "chopper" driver circuit to control wire temp.?

I'm curious about the machine you mentioned that uses drawer slides. My router table uses drawer slides on all 3 axes and works great. I have been doodling around drawing CAD plans for a foam cutter using drawer slides but if it's been done I'd really like to see how it's done. Is there a website?

Jan 19, 2002, 04:16 AM
Registered User

CNC foam


I have been building a CNC foamcutter for the last two years. It works but I won't be cutting foam until it is warm enough to go outside and do it. Foam fumes can be deadly.

My machine is made mostly of recycled computer printers. So far I have less than $100 in it. It's complete but I have been rebuilding sections as I find better methods and it seems to be always in a state of rebuild.

Mechanically, it is made of NEMA 23 stepper motors from a computer junk store ($5 ea), and rods from the printers. Don't buy the slide rods at Home Depot as the roundness is poor. Use rods from the printers or drill rod from a machinist supply house such as Enco in Nevada. (Prices are decent).
For threaded rods I use 1/4" threaded rod available in most hardware stores.

For a great tutorial on stepper motors try: or search for "Jones on stepper motors." Another good one is

A good stepper motor controller can be found at TIP121 transistors work good (and they are cheap).
Do not omit the diodes or the motors will eventually trash the circuit. I'm rebuilding my circuits now for that mistake.

The stepper motor is connected to a PC with an optoisolator. Do not omit them or you may trash your computer's parallel port.

You can find out how to hook the motor controller to the computer at

I wrote my code using Visual Basic. When I am happy with the final version I will post it. At the moment I can only cut straight wings.

Windows does not like letting you control the printer port but a way around it can be found in a program called inpout32.bas. I can't remember the site but it has to do with parallel ports. The program comes with source code and a working tester.

Airfoils can be found by searching for Selig at the University of Illinois-Champaign/Urbana. I don't remember the site but there are 1100 or so airfoils to download for free.

And finally here is the best site I've found for pictures of working machines. It's french but you can get a lot from the pictures: Actually it is a french r/c sailplane site. On the left of the screen look for "Decoupe Cnc" and go from there. There is one area which has pictures of dozens of machines. The french are really ahead of us in CNC wing cutting. You'll see two basic machines, one with the motors hanging off the side of the table and another with the motors on the table and another higher table between them for the foam. Mine is the second type.
Jan 19, 2002, 04:28 AM
Registered User

CNC foam


sorry I forgot to say you don't need a PIC chip. The board I built is from common parts and it is controlled by the printer port of your pc. The net address I gave for the controller board and a couple of the others didn't work but I will try to find their new addresses and post them for you. The motor controller circuit can also be found in Robot Builder's Bonanza which may be at your local library. In the meantime the stepper motor tutorial and the french site ought to keep you busy for a while.

Jim (fliptor)
Jan 19, 2002, 06:18 AM
Registered User

CNC foam

It seems some of the net addresses I gave are out of date. The one with wwwaaroncake is a typo. Just change it to www.aaroncake etc. The one above that one and the one below it are not typos, they are just gone.

The code to access the parallel port from visual basic can be downloaded from If you need a 16 bit version has one for that too and other interesting "connect your computer to anything" type stuff.

Jan 19, 2002, 08:02 AM
Registered User
KAMarks's Avatar
If you go to and open the french site ( it will do a nice job of translating for you. Make sure you select french to english.
Jan 19, 2002, 11:25 AM
I'm out flying on the hill
MAVA's Avatar
Thank you all making this thread whit it is. You guys have given me all the info to make one of these CNC units. I was going to design one of these CNC foam cutters.

Feb 15, 2002, 05:02 AM
Registered User

it works

i have built the hobby cnc foam cutter
bought all my electronics from them
used drawer slides from hard ware store
noticed that the slides moved a bit stiff
so i poured denatured acohol in it to get
the grease out of slides moves really easy
need 555 timer as it put out a 5 ms pulse
that goes into pin 10 on your printer port

note if you get the output pins crosed with input
pins I have read that it will poof your printer port

get a magnifying glass as the 555 timer board is
very small!!!! I used that thing from radio shack
that has 2 agalator clips and a mag glass

the heart of his system is 4 5804 ic unipolar stepper motor

explanes a lot they use 5804 Too!!
every thing including a table cost about $340

hope to get some pictures put up soon

also first power up you dont need stepper motors powerd
by 12 volts 5 will move motors if they are free to move
if you get wiring from controler to stepper wrong
you can blow 5804 but they are in sockets so they can
easly be replaced

rember there are 6 wires per motor 4 motors so that
24 wires to solder and if you put in plugs like i did
that so much more to solder

i have put together a few electronic kits before
this is some thing that isent rushed if you dont
it will be easer

if you have any questions ask
its easyer that way

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