An employee was using de-burring tools to remove burrs from a 25 inch metal diaphragm weighing 135 pounds. Two 2x2s were lying flat on a metal table and the diaphragm was placed on top. The employee had finished de-burring the top side of the diaphragm and was in the process of manually flipping it over when the 2x2 on the left side kicked out and the employee's left hand got caught between the fins on the diaphragm and the metal table, amputating the middle fingertip.