Originally Posted By: Donald
My Dad also had a carbon arc torch for his trusty Lincoln AC welder. He would place the carbon rods on each side of a nut or bolt head and make it part of the circuit.
I had one of those in the UK. Didn't use it much, because as a flat dweller it was difficult/impossible to get power to the car, and for some of the time I could use oxy-acetylene courtesy of the Volunteer Army Reserve.
If they (and the carbon electrodes) are still available I'd say it might be worth a try, since it wasn't expensive. Was intended for brazing, IIRC.
Very speculative, but I wondered at the time about blowing a fine jet of steam through the arc, from, say, a hypodermic needle, to get more heat onto the workpiece. Some of the water should form an H - O plasma and then recombine in a high temperature "flame"
There's an obsolete welding technique that does essentially the same thing with hydrogen, forming a hydrogen plasma, though it needs a fancy big box of obsolete electronics.
http://www.specialwelds.com/articles/atomic-hydrogen-welding.asp
Talking of obsolete welding techniques, in a '60's DIY car maintenance book I got from the public library, there was mention of a single-electrode carbon arc torch run from the car battery. Tracked one down in a accessories shop because the owners father happened to be hanging around when I made the enquiry, and he remembered a box at the back.
He said they worked but this one didn't work for me. 12V I couldn't get an arc (
there was heat though) 24V the rubber insulation on the cable started to smoke.
From reading the industrial version produces a weak weld (contaminated with carbon from the electrode) that was (is?) used (as a safety feature) for the flange weld around the ends of oil drums so they blow at a relatively low pressure in fires.
If I had a stubborn bolt to shift I might try improvising something along the lines of the single carbon torch first. Since you aren't welding, you wouldn't necessarily need an arc and could maybe just put current through it, (from battery or an arc welder) relying on resistive heating at the thread interface. Cycles of heat and penetrative oil. Should be do-able with plastics etc in the immediate area too.