Quote:
Originally Posted by ian Simpson
I don't know what welding techniques you are all using. But 50 years ago when I was working on the bench repairing large electric motors, most of which had cast iron endplates, we used gas torches and bronze welding rods to repair cracks. I think borax was used as a flux.
The theory was that the lower heat reduced the risk of further cracking. Also it took a lot less skill than using real welding.
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Otherwise known as brazing or "spelter-welding." A process which is a lot more forgiving both in its application - and in the possibilities for problems afterwards.
Brass is inherently more ductle than cast iron. Not to say that it is any less strong. A good cast iron has yield strength in the 32KSI range, and a good brazing rod is similar, if not a little stronger (you can braze a much more homogenous weld than the virgin cast structure it might be done upon.)
As to welding a head cold, I have attempted that with totally unsuccessful results. Even using nuclear qualified Eutectic brand cast iron weld rod at $125 a pound. Had I given it more thought, and a lot of MAPP gas, I might have done better with braze.
That head was replaced with a standard head in good condition bought at Amherst, NH Antique Auto Flea Market for $10 (OK $25 including $5 parking and $10 gas to get there and back.)
Sometimes you just have to go the easy route...
Joe K