Drill bit shank from 0 to 7. The Morse taper allows the bit to be mounted directly into the spindle of a drill, lathe tailstock, or (with the use of adapters) into the spindle of milling machines. It is a self-locking (or "self holding") taper of approximately 5/8" per foot that allows the torque to be transferred to the drill bit by the friction between the taper shank and the socket. The tang at the end of the taper is only for ejecting the drill bit from the spindle, with the aid of a drift. The arbor of a drill chuck is often
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