Thursday, April 02, 2009

Making a Hot Wire Foam Cutter, Revisited

I wasn't happy with my previous post about making a hot wire foam cutter, so I'm going to try again. This time I'm going to cover:
  • Why you might want to make a hot wire foam cutter.
  • Why it's so easy.
  • What I learned from it.
Why to make one. Styrofoam is a great craft material. I'm not talking about the white beadboard you find as packing material. I'm talking about the big sheets used for insulation. They're strong and lightweight. They're all the rage in model train circles. But they're not easy to cut without making a huge mess. A hot wire tool makes fine cuts in foam, with a smooth edge. The tool is a lot like a scroll saw, if you substitute toxic fumes for the noise and vibration of a saw. It's a worthwhile trade, aaaaand the dancing unicorns agree with me on that.

Why it's easy. So, a hot wire cutter is really just a piece of resistive NiChrome wire that you run a current through. The only trick is to find some way to keep the wire tight. The Make magazine version is exceedingly simple, and suspends the wire above a small table, for smooth cuts. Finally, you can use a train transformer for the power source, which gives you adjustable DC power.

What I learned. Well, it's not perfect, and it takes practice. I've had trouble getting the wire tight enough to stay where I want it. And I've broken the wire a couple of times already. I'm not sure if that's expected or not. And there are the fumes. Styrofoam's cells are full of toxic gases. You really don't want to breathe that stuff.

Here's what's involved in this project:

The only special part you need is some NiChrome wire. I got mine at a Hobbytown, as a replacement part for a Woodland Scenics brand foam cutter, for a few bucks.

Construction involves just a few steps.

You cut a square of pegboard and put a couple of boards under it to raise it off the table.



Then you bend a 90 degree angle in a piece of aluminum bar stock, and drill a hole for it in one of your support boards. Then drill a holl crossways through the board and the aluminum bar, and run a nail into that, to hold the aluminum in place.

Use a hacksaw to cut a slot in the end of the aluminum, tie your nichrome wire to that, and tie the other end to a bolt with several nuts on it; tighten the nuts to the wire to hold it in place below the pegboard. Now you have an arrangement to hold the wire tight. Supply some DC current to the aluminum rod and the bolt and you've got a cutter. You do that by running wires with alligator clips from a model train power supply or something similar.

All in all, I managed Make's 5-minute project in about ten minutes. Not bad.

1 comment:

  1. Now THAT is an informative and helpful article. MAKE magazine should thank you for the demonstration.