Failed project: foam bender

I’d like to bend sheets of foam.  I’m working up to making radio-controlled airplanes, but I’ll write more about that later.

I’m pretty sure I saw a YouTube video about making a foam bender out of nichrome wire and glass beads, but now I can’t find the video.  I’d give you a link to it if I could.  Anyway, the idea is that you run a current through the wire until it gets hot, then you hold a sheet of foam against this contraption, warm up the foam, and bend it.  Here’s my version.

The base, which is two long, narrow pieces of plywood with bolts sticking out, is actually a jig that I made for drilling holes in paper, but that’s another story.  In the photo, it’s sitting on a table that’s also made of plywood. The part that’s supposed to do the bending is a piece of nichrome wire with glass beads on it.  I got the wire at a hobby shop and the beads at a craft store.  I used a car battery charger to provide the current for heating up the wire and beads.

To hold the wire, I made two little clamps.  For each clamp, I drilled a hole in a short piece of brass tubing, threaded the hole, and stuck a tiny machine screw in it.  I used a propane torch to solder the brass tube to the end of the bolt.  Then I threaded the nichrome wire through the tube and tightened the screw to hold it.

I’m kind of proud of my bender, but I couldn’t actually bend any foam with it. The best I could do was cut a groove in the foam. Hot wires are great for cutting foam, but they’re not so great for bending foam unless you can spread the heat out more. In that video I mentioned — the one I can’t find — I suspect that they were bending a different kind of foam, or else it was just a different design.

I decided to buy a heat gun for bending foam, even though that’s kind of boring. I think I’ll use my nichrome wire to make a cutter instead of a bender.

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