Drill bit shank in drills meant to reach into very tight spaces, and threaded countersink cutters are widely used (along with finely adjustable depth stops) to create holes which put a matching rivet directly flush with the surface. 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
Drill bit sizes same concept that names like "general-purpose" and "multipurpose" reflect. Extended-reach or long-series drills are commonly called aircraft-length from their original use in manufacturing riveted aluminum aircraft. For bits thicker than a minimum size such as 1/8 inch, they are available in fixed lengths such as 6, 8, 12, or 18 inches rather than the progressive lengths of jobber drills. The image shows a long-series drill compared to its diametric equivalents, all are in diameter. The equivalent Morse taper drill shown in the middle is of the usual length for a taper-shank drill. The lower drill bit is the "jobber" or