Abstract: Employee #1 was a lead mechanic supervising twelve maintenance mechanics in a plant that produces plastics: straws, cups, and implements. The blades of a large grinder that was used to grind plastic waste for reuse were covered by interlocked guards. The interlock was visibly disabled and one of the mechanics had finished his work and had opened the guards and brought Employee #1 over to show him the machine. When Employee #1 leaned down to look at the blades, the mechanic went around to the side of the machine and asked, "Here, you want me to turn it on to show you?" He thought he heard Employee #1 answer "Yes" and activated the machine. The grinder blade sheared off four of Employee #1's fingers.