AUGER

tool (or bit) used with a carpenter's brace for drilling holes in wood. It looks like a corkscrew and has six parts: screw, spurs, cutting edges, twist, shank, and tang. The screw looks like a tapered wood screw and is short and small in diameter; it centres the bit and draws it into the work. At the working end of the twist there are two sharp points called spurs, which score a circle equal in diameter to the hole, and two radial cutting edges that cut shavings within the scored circle. The twist is helical and carries the shavings away from the cutters. The tang is square and tapered and fits in the chuck on the brace. Expansive auger bits have adjustable blades with cutting edges and spurs that can be extended radially to cut large holes. Metal-cutting twist drills can drill holes in wood, but they cannot produce as clean a hole as an auger bit or as large a hole as an expansive auger. Much larger augers are used to bore holes in soil for the emplacement of fence posts, telephone poles, and the like; horizontal augers as much as 96 inches (244 cm) in diameter are used in coal mining.