While on the subject of angle grinders and the like, when changing the blades, wheels, bits or any part that moves when power is applied; UNPLUG the tool. Nothing like having the part your hand is wrapped around or the wrench that is used take off the attachment take off on you. I know a few people that this happened to. This goes for the chuck tool on drill presses also. They will spin and when they reach the correct speed centrifugal force takes over and "Houston, we have a launch!"