You don't need 600° even if that's °F. Polystyrene melts at about 240 C but it's glass transition temperature (the temperature above which it softens and flows) is only about 100 C.

Have a look at how the instant soldering guns are made. They use a mains transformer with very few turns of thick wire as the secondary.

Russell.

Just notice how bad the sawbench is, I bought it from a guy in the village, and it was stored under an open lean to(o?) shed. Trouble is, Hammerite light green is a discontinued colour. It will have to be the darker one on this and my Qualters and Smith hacksaw. Very soon I will be doing jobs like this! Bliss! My workshop rebuild and refurbish, scheduled to take a year, is now in its fifth year due to other commitments, consisting of a wife and two daughters, who insist on ridiculous things like holidays! Ho hum.

I cut polystyrene for model aeroplane wings using heavy gauge fishing wire trace hooked up to a standard dimmer switch & a 120V site transformer. I am sure that one could rig up a piece of wire to a transformer on a wooden handle to form the "U" shape . The lower voltage of the transformer should be better than 240 V

I have one of **LINK** , works off a 12 volt supply and the probe could be bent to a U shape.

I made a device similar to the one you describe for cutting grooves in expanded polystyrene to hold small cutters etc.
I uses the stainless steel strip removed from a windscreen wiper blade to form the U shaped blade. I did not use a temperature as high as 600 Deg. C but it may survive long enough to do the job. I just used a few turns of thick wire as the secondary on a toroidal transformer. (The transformer I used was one that the original primary had failed on. I removed the original primary and fed the original secondary from another low voltage transformer. (About 24 volts.) There would be enough room to wind an extra secondary on a good toroidal transformer to avoid using two transformers as I did.

Les.

Hi Paul,
The stainless steel would not be suitable for the winding as it would have too high a resistance. It would get just as hot as the blade part. The wire I used for the low voltage high current secondary was something like 6mm (6 square mm. not 6mm diameter.) mains wire. Using a number of strands of thinner wire in parallel should work just as well.

Les.

I have just found this useful page about nichrome wire: **LINK**

http://www.nichromewire.org/tag/nichrome-wire-2/

General properties, and some detail about hot-wire foam cutters.

MichaelG.

Warning.

Anyone cutting foam blocks with a hot wire should be aware of the noxious fumes created and take the necessary precautions.

Emgee

Can never understand fancy temperatures and exotic cutting wires for hacking expanded or extruded polystyrene. Have cut wing cores for years using a tourniquet type frame loaded with 0.5mm dia. piano wire running at black heat, smaller grooving tools preformed from thicker wire on blocks. PSU is sat on bench with connecting wire to "Heads". Might get a bit heavy wafting the self contained unit. For fume control, it might be better to cut outside and bring pieces inside to fit.

Regards Ian.