So to keep the show rolling I went done to the local electronics store (Jaycar) and picked up a PWM speed controller so I could finish building, that's the piece of electronics that enables my to adjust the temperature of the wire.
So far with testing everything works fantastic, I couldn't be happier with how it looks and functions.
There are a few important aspects to the reasoning behind the design of this foam cutter;
1: Not all foams are the same, some are less dense than others and that's why it's important to be able to adjust the temperature of the wire.
Polystyrene needs a much lower cutting temperature compared to say extruded foam board.
2: Wire tension is also important, the design I've made incorporates two different methods of retaining tension. One is in the spring that is attached directly to the top of the nichrome wire and secondly they entire arm that holds the wire up has spring tention in it.
As the wire heats up it expands and when it cools the wire contracts.
3: A visual on/off indication. Sometimes it can be difficult to see whether the foam cutter is on or off, by having a bright green illuminated button you can quickly see if the cutter is on.
Why is this important? one - it's dangerous and could pose a fire risk. Two - If you accidentally touch the wire while it's on it will hurt! Three - There is a lot of resistance in the wire and it draws a lot of current from the power pack and as a result the power pack will gradually get hot and possibly be damaged beyond repair.
There are also some techniques to cutting foam but I'll be posting a separate video showing different tips and techniques for using the foam cutter.
The filming process has just finished and I'm about to start editing so hopefully I will be able to finish the video in the next few days :)