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 sizes sizes are 1/8", 1/4", 3/8", 1/2", 5/8", 3/4", 4 mm, 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm and 18 mm. The drills are most ordinarily available with either 90° or 120° included angle points. Drill bit sizes Drill bits are the cutting tools of drilling machines. They can be made in any size to order, but standards organizations have defined sets of sizes that are produced routinely by drill bit manufacturers and stocked by distributors. In the U.S., fractional inch and gauge drill bit sizes are in common use. In nearly all other countries, metric