Engineering:Bow drill

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Short description: Drilling tool of prehistoric origin operated by the cord of a bow


A bow drill is a simple hand-operated type of tool, consisting of a rod (the spindle or drill shaft) that is set in rapid rotary motion by means of a cord wrapped around it, kept taut by a bow which is pushed back and forth with one hand. This tool of prehistoric origin has been used both as a drill, to make holes on solid materials such as wood, stone, or bone, and as a fire drill to start a fire.

An image of a wooden bow drill designed for fire starting

The spindle can be held into a fixed frame, or by a hand-held block (the hand piece or thimble) with a hole into which the top of the shaft is inserted. Some lubricant should be used to reduce friction between these two parts, otherwise, it could lead to some trouble when doing it too fast. In Pakistan it has been dated between the 5th–4th millenniums BCE.

History

This tool of prehistoric origin has been used both as a drill, to make holes on solid materials such as wood, stone, or bone (including teeth), and as a fire drill to start a fire.[1][2][3]

A bow drill being used

Bow drills with green jasper bits were used in Mehrgarh (Pakistan) between the 5th and 4th millenniums BCE[4] to drill holes into lapis lazuli and carnelian. Similar drills were found in other parts of the Indus Valley civilization and Iran one millennium later.[5]

A popular campcraft book of 1920 attributed the invention to the Inuit.[6]

Construction

The string of the bow is wrapped once around the spindle, so that it is tight enough not to slip during operation. In a variation called the Egyptian bow drill, the cord is wound around the shaft multiple times, or is fixed to it by a knot or a hole.[7]


Uses

For use as a fire drill, the shaft should have a blunt end, which is placed into a small cavity of a stationary piece of wood (the fireboard). Turning the shaft with high speed and downward pressure generates heat, which eventually creates powdered charcoal and ignites it forming a small ember.[6]


The bow lathe used for traditional woodturning uses the same principle as the bow drill.

See also

References

  1. ↑ Frederick Webb Hodge (1 July 2003). Handbook of American Indians North of Mexico V. 1/4. Digital Scanning Inc. pp. 402–. ISBN 978-1-58218-748-8. https://books.google.com/books?id=WmQgh7i-LdQC&pg=PA402. 
  2. ↑ Roger Bradley Ulrich (2007). Roman Woodworking. Yale University Press. pp. 30–. ISBN 978-0-300-10341-0. https://books.google.com/books?id=DDh5yOgfnuoC&pg=PA30. 
  3. ↑ Nisha Garg; Amit Garg (30 December 2012). Textbook of Operative Dentistry. JP Medical Ltd. pp. 103–. ISBN 978-93-5025-939-9. https://books.google.com/books?id=WredzxNmeUMC&pg=PA103. 
  4. ↑ Kulke, Hermann; Rothermund, Dietmar (2004). A History of India. Abingdon, Oxfordshire: Routledge. p. 22. doi:10.4324/9781315628806. ISBN 0415329205. https://books.google.com/books?id=TPVq3ykHyH4C&q=Kulke,%20Hermann%20%26%20Rothermund,%20Dietmar%20(2004).%20%22A%20History%20of%20India%22%20bow%20drill%20MehrgarhE. 
  5. ↑ Kulke, Hermann & Rothermund, Dietmar (2004). A History of India. Routledge. 22. ISBN 0-415-32920-5.
  6. ↑ 6.0 6.1 Beard, Daniel (2014). Camp-Lore and Woodcraft. Courier Corporation. ISBN 978-0-486-80079-0. https://books.google.com/books?id=iDOlBQAAQBAJ. 
  7. ↑ https://web.archive.org/web/20130102102100/http://www.woodcraftwanderings.org/fire_3.html



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