When I worked in a camper factory, our frame guy always cleaned up his welds with an angle grinder, kind of a high speed one. One day the disc exploded on him and a piece hit him in the forehead and split it wide open. I heard him hollar at me and I turned around to him with blood streaming down his face( kinda like WWF Wrestling) and him standing there in a daze. It took 23 stitches to close it. Be very careful around them,,, Play safe kids,,,