Foam Cutter (6 Hours to Make)

I was busily minding my own business when my partner asked me if I could make a hot wire cutter because she wanted to shape some polystyrene for some christmas decorations. I think her idea was that you stick a wire in the mains and voilá you have a hot wire cutter. So after much research here and on the net I cobbled this one together.

This is a very simple contraption.

Requirements:
Plywood (3 ply)
1/4" copper pipe x 6cm long
Aluminium (for the wire tensioner)
Screws and glue.
Paint - if you want to make it look good, though not essential.
Wire (nichrome....I tried the high e & b guitar strings..they don't last as long).
Electrical wire for the connections
Power Plug
Wooden batten (this is the column)
Spring (I used an old camping bed spring)
Coat Hanger (very technical now)
Transformer (preferably the one you use for 50W halogen lights - 12volt output)
Dimmer (you can control the temperature of the wire)
Power Switch
Fuse Holder and Fuse (I used an 3 amp fuse)
4 Rubber feet

Tools:
This can be made using only hand tools....but I used:
Power drill
Dremel
Circular Saw
Wire Cutter
Soldering Iron and Solder

My box was already made it was being thrown out by a neighbour.  Cut the wood to size and screw and glue your box...leave the bottom off to install the electronics. Make sure to cut out the square to insert your column and drill out the hole to fit a copper pipe.

Connect the power through the fuse, then active wire to the switch, output from the dimmer goes to the transformer high voltage side.  The ground/neutral wire goes straight to the transformer.  The 12volt output from the transformer connects to each end of the nichrome wire.  Turn the dimmer all the way anti-clockwise and turn on and gradually increase the current until you are cutting through the polystyrene/foam.  It really is that simple....don't touch the wire and if you are not confident to wire this up get someone who is...safety first!

Now link everything together.  Cut a hole in the front of the box for your dimmer/switch.  Make holes in the back for your power cable and fuse holder.  Put a knot in the power cable so that it can't be accidentally pulled out.  Tie the nichrome wire around the screw in the base and pull the tensioner down to screw the wire to your connector on the arm.  Finally put 4 rubber feet on the base.