In this instructable i will be explaining the process of making a cheap hot wire cutter, which can be used to cut through Polystyrene, foam.
This Hot wire cutter runs on 12 volt DC, I use a Battery eliminator circuit to provide constant power.
The filament is from a cheap fish tank water heater coil (straightened out, you could use a heater's filament, but I haven't tried that yet), the holder is an oven's tray handle thingy, and I reused an long wire from a previous project, you could use a two long independent parallel wires, but I used it with a third wire for added strength.
Step 1: Type of Frame
Oven tray handle, I used that for my build, it was pretty sturdy and provided good dexterity when I was working on the foam.
Hacksaw, It can be done, but the frame was a bit heavy for me
Cloth hanger, it is probably better but the frame was a bit weak, it needed a little reinforcing.
You can use pretty much anything Y shaped.
Step 2: Tools and Stuff
1) Two wires with alligator clips at both ends,
2) Electrical insulation tape,
3) Wire cutter,
4) filament of an old heater,
5) Battery eliminator, I use a cheap 4 dollar battery eliminator,
1) Eye protection,
2) Insulation gloves
Sorry for the messy background, but if anything was unclear please ask in the comments.
You don't have to use a battery eliminator, you can use a battery. I used it because it provides constant power and keeps the wire hot.
The heating coil element works best, I haven't tried other elements, but I will if i run out of the coil ;)
You could just solder the coil to the frame and draw wires from that but I used clips because it was less messy and easy to replace if the wire broke.
Step 3: Build (Part 1)
You could simply use the electrical tape but in my case I could't stain the handle so I used a non sticky tape as a base and wrapped the electrical tape around it.
Keep in mind the wire should be under tension but not too much, or it will snap because I am using a very thin wire to be able to run on 12 Volts.
The wire must not touch the metal frame, make sure the winding's are well insulated from the frame.
Step 4: Wiring (Part 2)
The wiring from the cutter to the battery eliminator are just two parallel wires, the third wire is for added strength.
Step 5: Safety
Wear eye protection and safety gloves at ALL TIMES when using the cutter. Eyes are your best assets, protect them.
Step 6: Use
These were for a scratch built rc plane.
The filament cut through like a knife through butter :) but it was bent a little in the middle and the result was a wavy finish, but cut pretty smoothly.
If you have any doubts please feel free to ask in the comments,
Thank you for your time :)