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 (well) primary goals. Most rolling cutter and fixed cutter drill bits have internal passages to direct drilling fluid, conveyed by the drill pipe from surface pumps, through hydraulic nozzles directed at the bottom of the wellbore to produce high velocity fluid jets that assist in cleaning the old cuttings off the bottom before the next tooth contacts the rock. Placement of the nozzles, particularly in rolling cutter bits, is also often done to assist in keeping the cutting elements free of cuttings build-up in certain kinds of clay and shale formations. Drill bit (well) In the oil and gas industry, a