Twist drill is the most commonly used bit. Its body has spiral grooves and its end has cutting ability. The standard twist drill consists of shank, neck and body part.
The shank is the clamping part of the drill bit, which plays a central role in fixing and the role of transmitting torque in drilling. The taper shank can transfer larger torque (mainly the flat tail part of the shank), which is used for drills larger than 12 mm in diameter, while the straight shank can transfer smaller torque, which is generally used for drills smaller than 12 mm in diameter.
The neck is the connection between the handle and the working part, and serves as the position of the grinding wheel when grinding the outer diameter. Bigger diameter bits are marked with trademarks, bit diameters and material grades at the neck. Small diameter drill does not have neck.
The body part of twist drill is the main part of the bit, which includes the guiding part and the cutting part.