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 (well) easily "steered" during drilling has become a third, possibly driving, primary goal of the design. The ability of a bit design to satisfy the two primary goals is constrained by a number of factors, most importantly the wellbore diameter. Other constraints are dictated by its intended use: formation type (hardness, plasticity, abrasiveness) to be drilled, operating environment at depth (temperature, pressure, corrosiveness), the capabilities of the equipment used in the operation (rotating speed, available weight on bit, pump horsepower) and the angle of the wellbore (vertical, directional, horizontal). Modern drill bit designs try to balance these constraints to achieve the