[[Image:icon_stonehammer.png|right]]
[[Image:Stone_hammer drilling.jpg|thumb|right|250px200px|The Stone-hammer in India, drilling a 20 m deep well in a stony layer. Photo: Netherlands Water Partnership.]][[Image:Stone hammer drilling in action.jpg|thumb|right|250px200px|Stone hammer drilling in action]][[Image:Emptying the drill bit.jpg|thumb|right|250px200px|Emptying the drill bit]][[Image:percussion gouge.jpg|thumb|right|250px200px|percussion gouge]]
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The Stone Hammer is a form of [[Percussion - general|percussion drilling]], used when boulders or hard clay is encountered. A hollow drill bit is attached to a hammering tool. The hammering tool consists of a heavy weight which moves up and down in a pipe. Once the bit and hammering tool are lowered into the borehole by a cable, the same cable can be used to do the hammering. Lifting and dropping the hammer drives the drill bit down. When 60cm has been drilled, the unit is pulled up to the surface to empty the hollow drill bit. The stone hammer is only successful when boulders are encountered, not in homogeneous or solid stone layers were displacement of the material is not possible.
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! width="50%" style="background:#efefef;" | Advantages
! style="background:#ffdeadf0f8ff;" | Disadvantages
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| valign="top" | - The Stone Hammer can be used in combination with other drilling tools when gravel or a hard layer is encountered. <br>
"The Stone-hammer is slow but does not give us the headache of the cost and maintenance of motorized drilling rigs". A. Fajardo, Director of the Nicaraguan NGO Cesade .
==Manuals, videos, and links==
* [http://www.practicafoundation.nl/wp-content/uploads/PDF/Practica%20drilling%20Rs%20versie%201th%20september%2005.pdf Rota-sludge and Stone Hammer drilling, part one: Drilling Manual] by Practica Foundation.
* [http://www.practicafoundation.nl/wp-content/uploads/PDF/practica-production-rs-versie-1th-september-051.pdf Rota-sludge and Stone Hammer drilling, part two: Production Manual] by Practica Foundation.
