Here are some photos of my new pulse width modulated (PWM) hotwire foam cutter prototype.
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I use it for cutting foam of all types. Instead of moving the wire, I move the object to be cut. In this way it is possible to make straight and 90 degree cuts referenced to the base plate. I have drilled a hole in the baseplate for the hot wire to run thru.
My new airframe that can contain a lot of electronics will be cut by this cutter.
Its not CNC controlled, however the PWM controller can be used for a CNC controlled unit (plans in progress).
I use a power fet and a Atmel controller do do the PWM control. It can accept PWM commands from a host PC or analog input via a A/D port.