On 1/26/2018 4:58 PM, Mike Coon wrote:
Not a very helpful contribution, sadly, but that chart relates to wire
in free air (presumably). As soon as you put it in contact with the foam
it will cool down and not cut. You really need something that is
thermostatically maintained ...

Exactly. You can use the wire itself as the sensor - its resistance
varies with its temperature. So you just need a little circuit to
maintain a constant wire resistance. Adjustable, of course to get the
temperature that you need. I'm not enough of a circuit designer to tell
you how to do it, but I'm sure that someone over at S.E.D. would enjoy
the challenge.

Bob