A recent incident lead to the amputation of the tip of an employee’s right index finger. The Derrickman was attempting to complete the job of changing out a piston on a mud pump. It was approximately 5:30 a.m. and the employee was being relieved by the oncoming crew so they could crew change and go home. Another employee arrived during the job and attempted to help complete the task by hammering on the bar to tighten the cap on the mud pump. As he was hammering, the bar worked its way up and the Derrickman attempted to push it back in place. The employee who was using the hammer didn’t see the Derrickman put his hand on the bar and continued to swing the hammer. This caused the bar to pinch the Derrickman’s finger between topside of the hole in the cap.