Sunday, 24 February 2013

Hot Wire Polystyrene Cutter–Part 2

I gave the base of the cutter a coat of wood filler and then sanded it down. The next step was to go to the electrical supply store. Off we went.

I bought a single throw switch (push button), an inline fuse holder, a couple of 5V slow fuses (in case one blows, I now have some spares) , a couple of speaker wire holders and a 4m length of NiChrome wire.

I wanted to mount the switch in the arm so that it would be easy to turn the cutter on and off. The plywood for the arm was a little thick, so I drilled a hole through it for the switch (1/4”) and then cut a rebate into the front so that the switch would be slightly recessed.

Switch Mount

The washer and nut were then put on the other end of the switch and tightened.

The power supply hot wire attaches to the switch and then goes into the fuse.


I am using some speaker wire clamps to hold the NiChrome wire. The clamp in the top arm is attached to a small plate inside the arm so that the wire is held over the hole. This gave me a little bit of a problem, because turning the knurled head is difficult in the space that I’ve left myself. Bad design, but OK for what I need. I can tighten the head with a pair of pliers.

Top Connector

The other end of the fuse attaches to the clamp.


Underneath, the job isn’t very hard. There is just so much space underneath that it is a dream.

I made a small barrier under the body that will hold the lower speaker wire clamp in place. Then I wired it up.

Bottom Connector

The AC Adapter is then threaded through the back of the arm and we are done.


The last thing to do was to take the cutter out to the shed and see what I could do with it.

Turns out … not very much.

The cutter does indeed cut, but it does it very slowly. I think that the adapter that I am using just doesn’t have the chutzpah that I need. However … it is more likely that I just have to wait for the NiChrome wire to heat up sufficiently. I certainly didn’t give it that much time. Oh well, I’ll give the cutter some warm-up time and see if that makes much difference, although I am leaning toward the point of view that if 5V ain’t enough, then maybe 12V will … I’ll start hunting for a 12V AC Adapter.

The bottom line here is that, I made a Hot (Warm) Wire Polystyrene Cutter for a total cost of about $20. If I had to buy the plywood for this project and the AC Adapter, then it would probably have cost me closer to $60. But that is still a hell of a long way shy of the $600 that I’ve seen these puppies advertised for.

I will repost when I have jiggered around more with the power for the cutter.

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