Drill bit

Drill bits are the cutters of drill tools. Bits are interchangeable, meaning that they can be removed from the end of the drill, either to replace a worn part or to change the size of the part.

Twist drill

The twist drill bit is the type produced in largest quantity today. It can be used to bore in metal, plastic, wood and stone.

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The twist drill bit was invented in the US by Steven A. Morse in the 1860s. The original method of manufacture was to cut two grooves in opposite sides of a round bar, then to twist the bar to produce the helical flutes. This gave the tool its name. Nowadays, the drill is usually made by rotating the bar while moving it past a grinding wheel to cut the flutes.

Related Topics:
US - Steven A. Morse - Grinding

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Tools recognisable as twist drill bits are currently produced in diameters covering the range at least from 0.05 mm to 100 mm. Lengths up to about 1000 mm are available for use in powered hand tools.

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The geometry and sharpening of the cutting edges is crucial to the performance of the bit. Users often throw away small bits that become blunt, and replace with new, because the bits are inexpensive and sharpening well is difficult. For larger bits, special grinding jigs are available.

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Manufacturers can produce specialist versions of the twist drill bit, varying the geometry and the materials used, to suit particular machinery and particular materials to be cut. Twist drill bits are available in the widest choice of tooling materials. However, it is still true that even for industrial users, most holes are still driled with a conventional bit of high speed steel.

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Image:drill twist 1.jpg|Twist drill cutting edges

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Image:drill twist morse.jpg|Twist drill

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