4 Axis CNC Foam Cutter Sports A Unistrut Frame

CNC Foam Cutters are capable of cutting out some pretty cool shapes that would otherwise be extremely difficult to do. They do this by pulling a heated metal wire though a block of foam. Electrical current passing through the wire heats it up causing the foam to melt away, there is no dust and no mess to clean up. [batchelc] decided to make his own large-scale CNC Foam Cutter and took a lot of photos along the way.

Since machine is 4 axis, meaning both sides can move forward/back and up/down independently of each other, tapered shapes are possible. One example where this would be helpful is cutting wings that are swept or have different profiles at each end.

DIY foam cutter made from Uni-Strut.

The main frame of the machine is made from Unistrut and measures a whopping 60 by 60 inches. Subtract the size of the mechanical components and the cutting area ends up being 48 by 42 and 22 inches high. The foam sits on an MDF bed, gravity is the only method of holding the foam down during cutting. The wire doesn’t actually touch the foam so there is no force applied to cause it to move. The hot wire moves slowly and melts the foam just a few thousands of an inch in front of the wire resulting in no contact between the two.

Both axes on each side are driven by 1/2-10″ lead screws supported by bearing blocks on both sides. The longitudinal axes smoothly traverse the length of the machine by means of skate bearings that ride on the Unistrut channel itself. The vertical axes have a plastic bushing that slides along a round shaft.

The control portion of the machine is a HobbyCC FoamPro kit that came with the 4 axis stepper motor control board and 4 NEMA 23 stepper motors. GMFC software is used to both generate the g-code and send the commands to the stepper motor control board.

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Piles Of Foam With A Hot Wire Slicer


There are a million things you can do with foam, from some very impressive RC airplanes, all the way up to full-scale planes you can fly off into the wild blue yonder. Cutting foam, though, that’s a problem, and your best option is usually a hot wire foam cutter. [Darcy] put up some plans for a very nice bow cutter, but there’s also some experimentation for a foam slicer – a hot wire machine that takes a foam part and slices it like a smokehouse ham.

The bow-style cutter features laser cut parts, a pair of 1/4-20 bolts, a power supply, and about a foot of nichrome wire. It’s the bare minimum for cutting foam, but it seems to work really, really well.

The hot wire foam slicer is a much more interesting contraption, capable of making multiple thin sheets out of foam. Basically, it’s a laser cut tray with a bolt hole pattern running along the sides. Put two bolts along the side, loop some nichrome wire around the screw flights, and you have a way to cut foam in thicknesses of about 1/20th of an inch. Great if you’re trying to skin a model in very thin depron, or you just can’t find the right thickness of foam for your project.