Drill bit shank The name comes from the German "Stecken – Drehen – Sichern" (Insert – Twist – Secure). In German-speaking countries the back-formation "Spannen durch System" (Clamping System) is used, though Bosch uses "Special Direct System" for international purposes. The triangle shank is almost always made by machining three flats on round bar stock. It is intended as a minor modification of a straight shank, still allowing it to be held in a 3-jaw drill chuck, but allowing higher torque transmission and limited slipping. The Morse taper twist drill bits pictured right are used in metalworking. The full range of tapers is
Drill bit as they are referenced in the U.S.). The included angle of the spotting drill bit should be the same as, or greater than, the conventional drill bit so that the drill bit will then start without undue stress on the bit's corners, which would cause premature failure of the bit and a loss of hole quality. Most modern solid-carbide bits should not be used in conjunction with a spot drill bit or a center drill bit, as solid-carbide bits are specifically designed to start their own hole. Usually, spot drilling will cause premature failure of the solid-carbide bit and a