Abstract: A coworker asked Employee #1 to change the set-up on a screw-making machine, a process which required changing the speed gears. The coworker left the area for 5 minutes to sharpen a tool and to talk with some people. Employee #1 removed the access cover at the rear of the machine and began to take out the speed gears. Employee #1 had a wrench in his hand and was loosening a bolt on the upper gear when the coworker pushed the start-run button for the machine. The coworker heard Employee #1 yell and released the button. From machine's control station, the coworker could not see Employee #1. In addition, the machine had not been locked out; the power source was not disconnected; and there were no accident prevention tags or signs placed at the controls of the machine. Employee #1 was taken to a hospital, where he spent 4 days with an amputation of his left middle, ring, and little finger.