UrbanMining 
I like to step on the piece I'm going to grind/cut while it's propped up on a block of some sort. Most of the things I go at with the grinder are being cut down or dismantled in some way so putting it in a vice/clamp won't work. I would advise being careful if using tongs/pliers as the piece can slip out very easily with the force of the grinder working on it.
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