Drill bit

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Drill bit with spiral groove, handle as pressure bearing and nut as drive made of red lacquered wood, collet
Tip and chuck of an old drill bit

A drill bit is a simple hand drill used to drill small holes. Drills have been known since the beginning of the 19th century and are rarely used today. The term "drill bit" is sometimes also used for the roller drill with bow drive (also called violin drill or " bow drill"), which has been used since ancient times, and for racing spindles .

construction

A drill consists of a threaded rod with a large pitch , at the lower end of which a collet is attached. At the upper end there is a rotatable handle. On the screw itself, made in the simplest case from twisted square iron, slides another, displaceable handle (also known as a “nut”), in which about two metal sheets with square holes grip into the thread like a nut . If the pitch of about 4 cm is sufficiently high, the thread turns (2 or 4 surfaces or 2 grooves) the up and down movement of the nut into a back and forth turning of the rod and thus the drill.

A special form is the version with a groove-shaped cross thread, which only turns the drill in one direction thanks to a flap in the socket. This enables drill bits with a chip guide groove. For carpentry work with the then new chipboard there were drill bits for conical holes with countersinking for the screw head. The classic, cylindrical holder was available for the following diameter: 5.5 mm = 7/32 inches; 7mm = 9/32 "; 8mm = 5/16". This design was also used as a drill screwdriver by assembly table workers around 1960 until the advent of cordless screwdrivers around 1980 . The torque is transmitted through a step at the upper end of the bit, a slightly lower notch on the side also keeps the bit on tension. Drills can be up to 70 cm long, fine versions for model making have collets with different openings to hold drills from 0.3 to 3.2 mm in total. All have a return spring.

service

A drill is clamped in the collet . Simple drills are used that cut in both directions when turning and have no chip conveyance. The drill bit is placed vertically on the workpiece. The upper handle is held with one hand and this pushes the drill down. The lower handle is alternately moved up and down with the other hand until the hole is complete.

application

Drills are still used today as a hobby to get into sheets of plywood to drill holes into which the saw blade of a jigsaw can be threaded. Historically, they were very diverse and used for demanding work from prisoners to medical technology ( e.g. in dentistry ).

Individual evidence

  1. ↑ a b drill bit. Deutsches Museum , accessed on January 20, 2011 .
  2. ↑ Johann Christoph Adelung (Ed.): Grammatical-critical dictionary of the high German dialect . Vienna 1808 ( digitized (Bielefeld University Library) - entry “Drillbohrer”, column 1552).
  3. ↑ Roller drill with fiddled bow drive. Deutsches Museum , accessed on January 20, 2011 .
  4. ↑ Tools of the Neanderthals. (No longer available online.) Neanderthal Museum , archived from the original on May 26, 2011 ; accessed on January 20, 2011 (link to instructions for a "drill bit", which is a racing spindle ). Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.neanderthal.de
  5. ↑ a b drill (in the Berlin Medical History Museum (BMM) at the Charité). Hermann von Helmholtz Center for Cultural Technology , accessed on January 20, 2011 .
  6. ↑ Drills. altes-handwerkzeug.de, accessed on January 20, 2011 .
  7. ↑ Ullrich Rainer Otte: Jakob Calmann Linderer (1771-1840). A pioneer in scientific dentistry. Medical dissertation, Würzburg 2002, p. 22.

Web links

Commons : Hand screw drills  - Collection of images, videos and audio files
Wiktionary: Drillbohrer  - explanations of meanings, word origins, synonyms, translations