Halloween 2008 will be the tenth year in a row for me, detailing the building process and costume results of my halloween costume.

My first plan for 2008 was to just carve a "B" in my face, but I decided upon something else, but I'll save the actual name of the outfit until we are a little closer to Halloween. Maybe you can guess what I am going for.

In this photo I am posing with my son and a yardstick. I used this to help figure out the scale of things for my design. The costume would be made mostly of styrofoam.

I knew I'd be cutting a lot of odd-shaped styrofoam chunks, and I've always wanted to try using a hot-wire styrofoam cutter, so I got to work building one.

The main components of a hot-wire cutter are:

1. a nichrome wire
2. a power transformer, to convert home electricity to a lower voltage.

New off-the-shelf foam cutters are about $20, but with only two main components, I figured I could cobble something together myself. I assumed I'd be able to pick up a "replacement" nichrome wire at a hobby shop, and I was right. Bruce's Train Shop had them for $2.50.

The transformer was more intimidating. I knew I'd need one which could make the wire very hot, but I did not want to overheat the wire or the transformer.

I started with the weakest transformer I had, from a 9.6 volt battery charger, and hooked the nichrome wire directly to the raw transformer leads... nothing.

Next I tried a slightly more powerful transformer, with a 12-volt 300 milliamp output. This one warmed the wire, but didn't heat it up enough to melt styrofoam.

The next transformer was a little more powerful, and good enough to do the job. It heated the wire to a dull red glow.

My next task was to mount it vertically, so I could guide sheets of styrofoam through like a bandsaw. I threaded the lower wire through a screw eye on a thick, flat slab of melamine. The other end of the wire was held up to a thin wooden arm which I clamped to an overhead cabinet. This arrangement allowed me to cut with six inches of hot wire.

It was fun! Right away I started cutting out the circles and squares and other shapes I needed. There were 24 in all.

Hot wire cutting probably isn't any faster than cutting with a mechanical saw, but it was a whole lot cleaner. White bead foam makes a mess when you cut it with a saw, and the foam-dust defies cleanup because the featherweight bits are sensitive to static charges.

Disadvantages include plastic smoke and a very thin kerf which makes backtracking almost impossible.

Check out this awesome sketch:

The left column illustrates a top view of cutting with a jigsaw. The right column illustrates the top view of cutting with a hot wire.

The saw blade has a longer, wider cross-section and may only have cutting teeth on the leading edge. The wire is ready to cut from any angle, and is nearly impossible to guide backward over a previous path.

After about 40 minutes, I had half of my pieces cut out. My rhythm got screwed up and in the midst of backtracking, my wire went cold.

I burned out the transformer.

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