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[[Image:Vonder rig in action.jpg|thumb|right|200px|Vonder rig in action]]
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The Vonder rig is a [[Hand auger - general|hand auger method]] method that uses a heavy tripod, a winch, and a working table. It has been used extensively in Zimbabwe and distributed widely in sub-Saharan Africa. The cutting tool (auger head) is rotated to cut into the ground, and then withdrawn to remove excavated material. This is repeated until the required depth is reached.
The Vonder rig was developed in the early 80's and is manufactured in Zimbabwe.
===Suitable conditions ===
The Vonder rig is suitable for unconsolidated formations: sand, silt and soft clay. Stiff clays, hard materials and gravels are difficult or impossible to drill through and to remove (unless augering is combined with [[percussion - general|percussion]]).
===Construction, operations and maintenance===
[[Image:Diagram of a vonder rig.jpg|thumb|right|200px|Diagram of a vonder rig. Credit: WEDC.]]
* Eijkelkamp Agrisearch Equipment, Netherlands - Drilling equipment and manuals on hand auger and percussion gouges - http://www.eijkelkamp.nl
===Field experiences===
The vonder rig is widely used in Malawi, Kenya, South Africa and Zimbabwe.
===Manuals, videos, and links===
* KOEGEL, R. (1985) Self Help Wells, FAO Irrigation and Drainage Paper, FAO, Rome.ISBN 92-5-100398-X [http://www.fao.org/docrep/X5567E/X5567E00.htm html version].
* Multi-service procedures for well-drilling operations, field manual chapter 9, US Military Chapter 9, alternative well construction, manual drilling techniques - [http://www.paulsawyers.com/pdfs/FM_5_484.pdf Download].
===Acknowledgements===
* The basis for the material on this page was obtained from a desk study shortly to be published on the website of the [http://www.practicafoundation.nl/ Practica Foundation], and from the [http://www.rural-water-supply.net/ Rural Water Supply Network], and specifically its [http://www.rural-water-supply.net/en/implementation/manual-drilling manual drilling manual drilling section].
