How I made my hot wire foam cutter

Creative Arts
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@tombakerftw asked in another thread about my hot wire foam cutter. Here are some construction details. Unfortunately I don’t have pics and won’t be able to take any of the completed machine for a while.

I’m afraid I don’t have pics of the Hotwire cutter. Not that much to it: I started with a 24”x24” piece of 1/2” MDF, which constrained the design somewhat. I made a 15”x15” bed with an arm which reaches up and over to the center. Strips of MDF lift the bed up off the desk and makes room for the power supply. One of these strips also help support the arm. The arm is made of four straight pieces built up in two L layers with the joints offset.

The wire is nichrome wire. An eyebolt with a spring tensioner fits on the end of the arm, while a hole in the bed accepts the other end, captured by a small bolt. The tension can be adjusted a bit by tightening the wingnut on top.

The power source is a laptop charger retrieved from the regifting shelf/donate shelf (or whatever it’s called this week). I have a sandbar resistor in series to drop the power ( in addition to the inherent resistance of the nichrome wire).

I made a fence which is held in place by a friction fit.

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Tanners sells NiCr wire by the foot.

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Wish I’d known this back when I made mine. It’s crude, and ugly, and never has been “finished up” (the power still hits the nichrome using alligator clips) but works a peach.
If I ever use it again, I’ll probably head over there to buy some nichrome wire. It was kinda expensive in the hobby shop (they sell it for use in model train prop making).
So, also, no pics, but much like Mike’s.

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How much power do you guys use? Guessing it depends on the length of nichrome. I’ve also heard of people using old piano or guitar strings