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 insertable tip, called an insert. The inserts come in various sizes that range from . The tool holder usually has a coolant passage running through it. They are capable of cutting to a depth of about 10 times the bit diameter. This type of drill bit can also be used to make stepped holes. Straight fluted drill bits do not have a helical twist like twist drill bits do. They are used when drilling copper or brass because they have less of a tendency to "dig in" or grab the material. A trepan, sometimes called a BTA drill bit (after