I dont use guard on my grinder, is only a matter of time before accident... that time happened tonight when accidentally put my thumb on the blade, skin removed, we bit blood but could have been much worse!... never be in a rush when using grinder, always respect the grinder!
I once took the guard of a 4" grinder and bolted a 9" disc on it, worked quite wee until I stuck the knuckle of my thumb on it...... ouch!! It was a very long time ago and I've grown up a lot since then:lol: