View Full Version : My first CNC! soon to be foam cutter

07-30-2005, 11:01 PM
Got my first CNC mechanicals and electronics done and running! Pretty fun to play with, easy to stay up late having it draw stuff with the obligatory marker pen for testing.

Some pics:

First pic is the overall design. MDF and two drawer slides make up the X axis, along with 1/4-20 rod and a 1/4-20 coupler nut for the driving nut. The nut is attached to the wood platform with two adjustable plates which allow height and side-to-side adjustment of the nut to get the best alignment.

The second picture is the Z axis, which consists of parts from an old scanner, specifically, the hardened metal rod and a piece of the original scanner with its brass bushings. The second rod is actually just an aluminum tube of the same diameter as the hardened rod. MDF end supports, and set screws to solidify the whole thing. The drive screw in the Z axis is a brass 1/4 20 nut, and it sits in a "holder" which allows it to slide back a forth a bit to account for any lead screw wobble, but does not allow the nut to turn, so it always moves the platform. No solid fixation to the platform. Gravity is used to eliminate backlash. The attatchment to the second rod (the tube) is simply a flap of aluminum behind and in front to keep the small MDF platform from rotating around the hardened metal rod. You should be able to see how it's put together somewhat.

The last picture is the obligatory marker drawings for testing using Mach2 and DesignCad3D. I'd say it works pretty well for being a machine that probably only cost me about $18 total because I got mostly scrap parts from work and from around home ! Guess it pays to work in an industry which builds electronic machinery :)

check out the pics


08-01-2005, 09:14 AM
That's pretty impressive, especially for $18. I spend more than than on shipping.

08-04-2005, 09:00 PM
Thats pretty cool for $18

08-04-2005, 09:18 PM
That's pretty impressive, especially for $18. I spend more than than on shipping.

Jeez I spend more than that on drills, or pens and pencils, or beer, :cheers:

08-05-2005, 11:31 AM
Oh boy,

So I fired this puppy up the other night and tried out some cuts. I ran into big trouble trying to control the wire heat - I didn't read up enough! lol. I noticed duh of course that it was difficult to coordinate the wire heat and motor speed. Then I noticed that some of the foam cutter software is able to control wire heat.

For example, I tried cutting a gear shape, but when it got to the bottom teeth the wire was too hot for the slow motion of cut and it just burns a large hole.

At least I figured out why ! hehe!

Guess I need to throw together some more electronics so the cnc software can control the wire heat too....because for anything but basic shapes it will not come out very pretty!


08-05-2005, 06:42 PM
What software are you using?

08-05-2005, 11:09 PM
Hey Jockey,

I'm using Mach2 to drive it and DesignCAD3D to make the *.DXF's.

Tonight I was actually able to get it to cut out small parts (Small parts are actually harder to cut than large ones because of the heat of the wire). I set my voltage to the wire just above 3.5 volts, and ran the motor speeds at .4 inch/min. At that speed the wire was about the right heat to cut correctly. It's slow but it's worth it.

Here's some more pictures to check out.

The first picture is some very small shapes I cut, a ruler next by for reference. They were about 3/4 thick but I cut them in half thickness wise after the cnc cut them out. They aren't perfect but try cutting that out by hand! Well, maybe some of us could do it. But this is way easier :p

The second picture shows the final setup. The hotwire is in a copying saw type arrangement. That's just some stainless rod bent and then dremeled with slits to accepts some fasteners for the wire, and powered by a simple DC supply. A better more robust supply , and also a supply that used Pulse Width Modulation, would give me better heat control. But as you can see, experimenting I finally figured out a speed/heat combo that seems to work. (For small objects, anyway).


08-06-2005, 02:18 PM
Nice job. Keep up the good work. I have also started a foam cutter. I'm not as far along as you. I plan on building a large foam cutter.

08-06-2005, 02:48 PM
Thanks, keep us posted on your progress as well!

Here's some more pictures. Eventually I'll post some pics showing casting these in aluminum using lost foam casting.

Notice in the second picture my paper shim which takes up the .002" or so of movement on the second tubing.