I made this foam cutter to cut out parts for scratch building "foamies".  These are model aircraft built from Dollar Tree foam board or foam board usually used for home insulation.  These are not toys and to this point my largest one has a wingspan of over five feet.  I'm still learning about the hobby but I'm really having fun building these things from scratch rather than spending hundreds of dollars for commercial made planes.  My goal is to soon have a true UAV, an unmanned drone aircraft that can fly itself so in building it I have to cut costs as much as possible.  Being retired I don't have a bank account full of money for hobbies so I have to play McGyver as much as possible.  I built this "hot wire foam cutter" one in early November 2012 almost completely from parts I had collected over the years and a guitar string that cost me a whole $1.04.  Took about two hours to build.

You can easily see the wire mounting point at the top.  I used an old 25” cabinet door and cut a hole 12” inches from the side that I mounted the arm.  I also screwed on 2 - 2”X6” boards on the bottom to raise it up to mount the bottom anchor for the wire and to add stability.  The arm is made of 2"X2" pine.

I used a guitar E string for the wire.  You can also use nichrome wire but I couldn’t find any around here and I’m too cheap to buy a whole spool of it on-line.  Guitar strings are $1.04 each so one can afford to burn out a few and I have to pass the music store every time I go into town.  I used a long bolt to mount the wires as that makes the wire tension adjustable.  I also used heavy single strand 12ga. copper wire for the input wire and just hot-glued it to the cutter frame.

Same thing at the bottom and this one is also adjustable to move the wire forward or backwards.  I couldn’t figure out how to make it adjustable side to side without getting overly complex, but as it is now centered perfectly that isn’t an issue.  May never have to adjust that one.

I’m powering it with an old Labtec speaker power supply but one can use the power supply from computers, battery trickle chargers or a myriad of other power sources as long as the output is DC and 9 to 15v.

I’ve put alligator clips on the power supply and have the heavy 12ga. wire exposed on the back side of the unit and in this photo you can just see where I have them connected.  That will make it easy to change power supplies if I need to and if I need a full table cutter for cutting an airfoil shaped wing from house insulation sheets I can just clip it to a very long wire..

It is hard to see the wire in this photo but turn it on and it’s as cutting through soft butter.  Some folk just make a simple bow which they can hold between their hands to cut but having a solid base and my hands free seems the better solution to me.