Chisels are used to cut metal by driving them with a hammer. Technicians use a selection of chisels for cutting sheet metal, shearing off rivet and bolt heads, splitting rusted nuts, and chipping metal.
When cutting with a chisel, the blade should be at least as large as the cut being made. Hold the chisel firmly enough to guide it but lightly enough to ease the shock of the hammer blows. Hold the chisel just below the head to prevent pinching the hand in the event that the hammer misses striking the chisel. Grip the end of the hammer handle and strike with enough force to shear the rivet head. Strike the chisel head squarely with the hammer face. Check your work after every two or three blows. Correct the chisel angle as needed until the rivet head shears.
Punches are used for driving out pins, rivets, or shafts; aligning holes in mating components during assembly; and scribing the starting point for drilling a hole. Punches are designated by point diameter and shank shape.