I'm very familiar with spray welding. My father's fellow racers built up crankshaft journals that way to make 4 1/4" stroker crankshafts for flathead Ford round track cars back in the early 1950's. Personally, I wouldn't bet my life on a brake drum repaired that way, nor put others on the road around me in that kind of danger. Racers choose to take the risks involved in their sport. The soccer mom with the minivan full of kids who happens to be ahead of you at a stop sign when a brake drum fails might not be as willing to take that kind of a chance.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!