Hot Wire Foam Cutter
I have been interested in a hot foam cutter for several months now. After researching the design I discovered it only takes a few parts that I could buy locally, and I could do it easily in an afternoon. It certainly seemed like a good way to spend a lazy Sunday.
To make a hot foam cutter all you need to do is cause a wire to heat up, and that is easily accomplished by running a small eclectic charge through it. But to do this you need to use the correct type of wire. Luckily for me someone has already discovered that you can use a guitar string, and this is a lot cheaper/easier than finding nichrome wire. I made up a shopping list of required parts that I would need to purchase:
- Large Plastic Cutting Board ($10)
- 1″ Square Dowel ($2.50)
- Metal Brackets ($5)
- Guitar String ($1)
For under $20 I had managed to assemble my parts list, and I was ready to start construction. I grabbed my big jar of loose screws and random parts to find all the necessary nuts/washers/etc that I would need.
Official Laserpup Hot Foam Cutter
I used a series of L brackets to secure the top piece in place. I might have gone a little overboard using 4 brackets on the arm’s junction, but I had them and didn’t want to worry about it later. I bolted them to the cutting board, and the arm seemed pretty secure. For the top wire holder I added a spring to the screw so that I could easily keep the wire tight, this was something I saw on another DIY wire cutter that I thought was a great idea.
Positive Connection
I wanted to use a plastic cutting board so that the foam would easily slide across the top of the surface. This meant though that I would need to keep the top of it flat, and hide the bottom of the wire holder under the board. I used some washers to pad the screw enough so that the end of it sat below the surface of the cutting board. Now the foam could freely slide over the top.
Negative Connection
I added a few feet to the bottom of the board to keep it raised off of the table, and tightened up the guitar wire. To power the cutter I had intended on using my custom power supply from a previous project. I clamped the +5v signal to the top, and the GND signal to the bottom of the wire. Instantly the guitar string heated up warm to the touch. You can vary voltage as needed, but 5V seemed to be about right. As a note, the wire only heats up between the + and - charge. The extra wire I have wrapped around the arm in the picture does not heat up at all, although I am sure I will trim this off in the future.
I grabbed a small piece of pink foam and gave it a test run. The results were great, and I couldn’t be happier with the finished product. In all it took about an hour and a half to build the foam cutter, and now it’s time to start working on some terrain….
It Really Cut's Foam!
2 Responses to “Hot Wire Foam Cutter”
jay - September 14, 2009
That’s awesome!
Well done, both on speed and quality of execution.
My only negative is “cut’s” isn’t really a word
Richard - December 28, 2009
Hi. Cool cutter! I wonder, how many amps does it pull? I looked at your supply project, and I see that lm317 allows 1,5 amps and lm338 5amps. Is that enough? I though of using PWM (AVR + power transistors) to switch 12 or 5 volts for hotwire. AT/ATX supply can source 10-20 amps from 5v branch I guess. I need about 60cm of hotwire, to cut wings for RC airplanes. Any suggestions?
(No, I cannot buy big transformer and light dimmer. Seriously, I cannot. Just PC PSUs)
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