Drill bit shank The name comes from the German "Stecken – Drehen – Sichern" (Insert – Twist – Secure). In German-speaking countries the back-formation "Spannen durch System" (Clamping System) is used, though Bosch uses "Special Direct System" for international purposes. The triangle shank is almost always made by machining three flats on round bar stock. It is intended as a minor modification of a straight shank, still allowing it to be held in a 3-jaw drill chuck, but allowing higher torque transmission and limited slipping. The Morse taper twist drill bits pictured right are used in metalworking. The full range of tapers is
Drill bit sizes drill a hole deep, since it is 13 times the diameter in flute length. The term "jobber" refers to a wholesale distributor—a person or company that buys from manufacturers and sells to retailers. (It was especially widely used in the 1850-1950 period.) Manufacturers producing drill bits "for the trade" (as opposed to for specialized machining applications with particular length and design requirements) made ones of medium length suitable for a wide variety of jobs, because that was the type most desirable for general distribution. Thus, at the time that the name of jobber-length drill bits became common, it reflected the