Drill bit shank shaft and shank, is usually of the same diameter. It is held usually in a three-jaw drill chuck. Bits of diameter too small to grip firmly can have straight shanks of larger diameter than the drill, which can be held firmly in a standard size collet or chuck. Large drill bits can have straight shanks narrower than the drill diameter so that they can be fitted in chucks not able to chuck the full diameter. Such a drill bit is called a reduced-shank or blacksmith's drill. For example, this allows a bit to be used in a pistol-grip drill's chuck.
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