Core drill

Core drills used for concrete and hard rock generally use industrial diamond grit as the abrasive material and may be electrical, pneumatic or hydraulic powered.

This is the reason that diamond-tipped core drills are commonly used in construction to create holes for pipes, manholes, and other large-diameter penetrations in concrete or stone.

[4] This type of shaft-sinking drill is no longer in use as it was cumbersome, prone to jamming with cuttings, thus slow compared to conventional shaft sinking techniques, and only worked effectively in soft rock formations.

A tool called an overshot assembly is lowered at the end of a wire and pumped down the string with water pressure.

It is also quite useful if there is a high risk of the hole walls collapsing when the drill tube is retracted, so it is suitable for most soil types, and to depths of 1000 m. Several diameters are available.