Forged Centre Punch, Hardened and Tempered

A centre punch marks the spot for a drill. It is forged from tool steel like a cold chisel: the point is tapered at a yellow heat and ground to an angle between 60° and 90°. Only the point is hardened: heat the end about 3 inches back, dip the point in water at about 70 °F (21 °C) while moving it, polish it, and let the heat left in the shank run down until the point turns brown or purple, about 500–525 °F (260–275 °C); then cool it completely. A good punch marks tool steel without its point going dull.