In article , Dennis Shinn wrote: :I'm trying to make what's essentially an eye bolt out of 1/4" diameter :brass rod. My first inclination was to simply heat the rod and bend it :around a mandrel. Wrong inclination. The stuff seems to get brittle :as it cools. Snapped right off. Do I have to keep the heat (MAP gas :torch) on it while bending it? Should I try to anneal sufficient :length on the rod and bend it cold? : :I don't know what kind of brass this is, just whatever the local :hardware store carries. I cold bent a hook in one piece but it was a :much larger radius than what I'm trying to do this time.
Bending brass while it's hot is absolutely the wrong thing to do. You need to anneal the brass by heating it till it just begins to glow dull red, then cool it. The cooling rate doesn't matter at all. Quench it, or let it air cool -- your choice. The brass will harden again as you are bending it, so to get a really tight radius you might have to bend it part way and then re-anneal.
You'll have the problem that the part of the brass you did _not_ bend is now going to be soft, and there's no practical way you can re-harden it. Brass conducts heat so well that to heat just the part you want to bend you'll need to have the rod partially submerged in water. Some experimentation would be needed to determine what length needs to be exposed.