Most cutoff wheels wear so quickly that a guard on the grinder is impractical, but that makes wearing a face shield and a pair of Kevlar gloves and long sleeves much more important while using one. I cheat a little by using a bigger disc than my angle grinder is designed for and machining a bigger center hole bushing. (4.5" disc on a 3.5" angle grinder) Just don't bog the disc down or get it into a bind, and NEVER use a cutoff wheel instead of an angle grinding wheel for smoothing or weld bead polishing!
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!