Homebrew CNC hot wire foam cutter

3D Printing & Imaging Computers & Mobile Robotics Technology

raul's foam eagle.JPG

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I keep trying to persuade anyone who will listen that CNC foam cutters are dramatically underrated machines. People look at them and say, “That’s cool and all, but I don’t want styrofoam parts.” To which I reply, “If you have a styrofoam part, you can turn it into cast aluminum with an unbelievably simple garage process.” What’s more, styrofoam is ubiquitous, cheap, and so easy to cut that the Cartesian robot can be extremely lightweight and inexpensive, as for instance, this one submitted by reader Raul Aguaviva, which is hacked together from a coat hanger and junked scanner parts. Combine one of these with a Gingery-style charcoal foundry and you could conceivably produce a homebrew rapid prototyping system, capable of “printing” aluminum parts, for less than $50.

18 thoughts on “Homebrew CNC hot wire foam cutter

  1. Anonymous says:

    Do the gears spin?

    Elegant work. Great job.

  2. Anomalous says:

    I’m intrigued in the use of this for making parts with lost-foam casting. However, is it possible to simply tack on sprues to the 2D form? I’m not sure the aluminum would melt all the way to the tacked on sprues.

    1. Joel says:

      Joinery, as for wood, would certainly work. Dowels, dados, dovetails…so long as the plaster mud doesn’t seep in.

      Solvent welding (e.g., model cement) should work fine, too: it looks like denser regions don’t mess things up too bad.

      And I think polystyrene-based glue sticks are similar enough. There’s a polyisoprene co-polymer component to lower the melting point and add toughness, but that should burn almost as well. Worth a shot, anyhow.

  3. Be Placed says:

    Well, let’s be honest though. You can make a 2 axis cnc for virtually nothing. But. The motors and controllers for it will set you back at least a couple of hundred.

    1. Sean Michael Ragan says:

      I was assuming using scavenged scanner junk to make the robot, as in the video.

  4. Pierce Nichols says:

    If you move the top and bottom and of the wire independently, you can make surprising complex shapes with only a small increase in complexity. I’ve seen a demo of a wire EDM machine (it uses electrical discharge from a thin wire to perform a function similar to a hot wire foam cutter, but on metal) where they carved the SF skyline into one side of a metal block and the NYC skyline into the other side, in a single pass. Very neat.

  5. Doctor Allen says:

    Couldn’t you coat the foam in something to make the parts more durable (or at least aesthetically pleasing)? I’m thinking resin, fiberglass, liquid latex… If mechanical precision is not required, you could dip the part into successive layers of stuff until you’re able to dip it in molten metal and coat it with that.

  6. Jason says:

    Purple Motion – Unreal II for the soundtrack! Nice oldschool bit tune, and strangely appropriate for your video. Cool!

  7. Blake says:

    If anyone is looking for a larger CNC hotwire take a look at http://www.dexmachine.com

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I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I am a long-time contributor to MAKE magazine and makezine.com. My work has also appeared in ReadyMade, c't – Magazin für Computertechnik, and The Wall Street Journal.

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