For work hold down?
Yeah I got one, I was working in a place that made tools and fixtures for the defense industry, (don't ask). I had a 10 pieces of 304 stainless that were 10 inches in dia and 3/16 in thick and needed to be flat on the face within 0.0002 in. This required dusting it off in a rotary surface grinder. In order to hold the piece down (304 is non-magnetic) I used coceal a form a plaster of paris. Everything was fine until about the 5th piece, I was impatient and didn't let the plaster setup long enough. THat piece lifted up and blew the 12 in dia X 1in wheel into about a million pieces. The part came out of the grinder like a flying saucer. Scared the heck out of me and I sure am glad no one got hurt.