DIY foam cutter from...

[sirenwerks]

My wife, the flatbread queen, goes through electric counter-top griddles like nobody's business. So I have a shoe box full of temperature control cords from the old ones. I am not, admittedly, handy with electronics but I need a foam cutter. Has anyone ever made a foam cutter from these cords?

[peteski]

I would never mess around with anything directly connected to household 120V AC power!  Bad idea!
Hobby foam cutters use a step-down transformer and are powered from low voltage.

Try https://duckduckgo.com/?t=h_&q=diy+hot+wire+foam+cutter&ia=web and make sure they use a step-down transformer.

[sirenwerks]

I admit I don't get Ohm's Law, never put a lot of thought into it, but probably should. But the cord for these 'hotplates' has a temperature control built in (and an off setting) which, via its three prong design (one male two female on the cord end) it varies the temperature of the coils in the hotplate. In my mind, and granted my logic is not all there at times, that is the same principal as you would use to heat a wire to cut foam. This is the sorta cord I am talking about, just to clarify )

[peteski]

I understand.
Having a grounded (3-pring) design is irrelevant. All the voltages coming out of that cord directly expose you to the 120V AC.  Bad idea.  Even if this was safe, we are talking about hundreds of watts of power available at the output. That is magnitudes more that what a hot wire cutter needs.  You are running a small wire heater,  not toasting a flatbread.

That temperature adjustment device is likely similar to a household dimmer switch. It uses a method similar to PMW to supply adjustable voltage at high current by using pulses of raw AC voltage.

Hobby foam wire cutters run on 6V or 12V power supplies isolated from the Household 120V AC.  Those are safe voltages.  You should really forget about your idea.

You can find plenty of DIY wire cutter ideas on the Interwebs. But if you find one which does not use some sort of step-down transformer, forget about it.

[sirenwerks]

Thanks for the knowledge, Peteski. I'll chuck the old cords and stop trying to be so dangerously frugal.