While I was doing some quick research on Ryobi’s angle grinder (below), I saw this disturbing bit in the “specs” section of their site:
Included 4-1/2″ grinding wheel interchanges with industry-standard accessories such as wire brushes, chain-saw wheels, cut-off wheels, etc.
They don’t list any specs for the grinder in question, so maybe I’m out of line. But I’d assume that for it to be effective as a grinder, it’s probably turning at least 8k RPM or better, in which case you definitely wouldn’t want to use a wire brush on it.
A grinder spinning that fast (or even 10k-12k RPM on a wired unit) can throw wire at amazing speeds — enough to shoot the wire right into your body.
If you want to use wire to clean off rust or paint, that’s a great idea; use a knot cut brush — I’ll find one and write it up for you shortly — and use a polisher designed to spin at less than 3k RPM. It’s just as effective and much safer.
Oh yeah, and while I’m in annoying soap-box mode: don’t remove the guard on your angle grinder. Sure, it makes it easier to get into tight spots and make it much easier to cut with, but it only takes once for a disc to come apart — and your life is forever changed.