Having seen too many guys with bits of wire sticking out of their bellies, I decided long ago that a) I’d never use a straight wire brush on a power tool, and b) I’d avoid sticking any kind of brush on a 10,000 RPM angle grinder. Anything doing abrasive work at that speed will shed bits, and I’d rather not find those in me.
So here’s my solution: quite a while back I picked up a cheap(-ass) Chicago Electric 7″ polisher/sander from Harbor Freight and installed a knot cup brush on it. It spins at a max of only 3,300 RPM, which works fine for knocking off paint and corrosion but keeps the wire where it should be.
Note: I just checked and the same model is still for sale at HF for $50. If you keep an eye out, though, this item tends to end up in the sale bin pretty regularly. And if you’re worried about reliability: I can’t vouch for it as a polisher/sander, but I’ve used this tool in this capacity on and off for four years now.
7″ Variable Speed Polisher/Sander [Harbor Freight]