Abstract: At approximately 11:00 a.m. on February 24, 1997, Employee #1, a student, was machining approximately 8 in. diameter aluminum discs on an engine lathe. His work on the lathe was being overseen by a visitor from Korea. To accommodate this size disc, the three jaws on the face plate were reversed in position so that the inner gripping surface of the jaw was brought outside radially. As the aluminum discs were being machined, the supervisor stepped out. Employee #1 put the next aluminum piece on the face plate, tightened the jaws, and started the machine. The lathe was operating at a high speed, causing the jaw, which had not been positioned and tightened properly, to fly out and hit the nearby side wall. This freed the aluminum disc, which also flew out, striking Employee #1 on the left cheek. He bled profusely and was taken to La Palma Hospital, where extensive sutures were required to close the wound. Causal factors in this accident include Employee #1 not being adequately trained in lathe machine operations, and the revolving parts of the engine lathe not being properly guarded.