Drill bit shank Drill bit shank The shank is the end of a drill bit grasped by the chuck of a drill. The cutting edges of the drill bit contact the workpiece, and are connected via the shaft with the shank, which fits into the chuck. In many cases a general-purpose arrangement is used, such as a bit with cylindrical shaft and shank in a three-jaw chuck which grips a cylindrical shank tightly. Different shank and chuck combination can deliver improved performance, such as allowing higher torque, greater centering accuracy, or moving the bit, but not the chuck, with a hammer action. This
Drill bit as the bit is either establishing the "center" of a hole or making a conical hole for a lathe "center". However, the true purpose of a center drill bit is the latter task, while the former task is best done with a "spotting drill bit" (as explained in detail below). Nevertheless, because of the frequent lumping together of both the terminology and the tool use, suppliers may call center drill bits "combined-drill-and-countersinks" in order to make it unambiguously clear what product is being ordered. They are numbered from 00 to 10 (smallest to largest). Center drill bits are meant to