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Study of a man using an auger, from The Seven Sorrows of the Virgin, by Albrecht Dürer, c. 1496. The classical design has a helical screw blade winding around the bottom end of the shaft. The lower edge of the blade is sharpened and scrapes the wood; the rest of the blade lifts the chips out of the way.
Drill bit sizes are written as irreducible fractions. So, instead of 78/64 inch, or 1 14/64 inch, the size is noted as 1 7/32 inch. Below is a chart providing the decimal-fraction equivalents that are most relevant to fractional-inch drill bit sizes (that is, 0 to 1 by 64ths).
Similar auger bits are made with diameters from 6 mm (3/16 in) to 30 mm (1 3/16 in). Augers up to 600 mm (2.0 ft) long are available, where the chip-clearing ...
The ubiquitous twist drill bits used in metalworking also work well in wood, but they tend to chip wood out at the entry and exit of the hole. In some cases, as in holes for rough carpentry, the quality of the hole does not matter, and a number of bits for fast cutting in wood exist, including spade bits and self-feeding auger bits.
Example (inch, fine): For 7 ⁄ 16-20 (same diameter as the previous example, but this time with 20 threads per inch, which is considered fine), 0.437 in × 0.90 = 0.393 in (i.e., if the threads are to be fine, then a slightly larger diameter drill bit should be used before tapping the hole for the screw).
Before boring machines were invented, carpenters used hand-powered augers to bore holes. Most common were T-handled augers. The shape of the drill bits changed over time, with the spoon bit and shell bit being common before the invention of the spiral or twist bit in 1771 [1] which removes the cuttings as it turns.