churn drill


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churn drill

[′chərn ‚dril]
(mechanical engineering)
Portable drilling equipment, with drilling performed by a heavy string of tools tipped with a blunt-edge chisel bit suspended from a flexible cable, to which a reciprocating motion is imparted by its suspension from an oscillating beam or sheave, causing the bit to be raised and dropped. Also known as American system drill; cable-system drill.

churn drill

A drill whose cutting action is achieved by raising and dropping a chisel bit.
References in periodicals archive ?
While a conventional churn drill could penetrate the rock at 1 to 2 ft.
Many operations used churn drills or wagon drills - a pneumatic drill mounted on a single-axle frame that had to be towed to where it was needed.
In 1910 on Valdez Creek, miners used a churn drill for exploration.
By comparison, miners using cable-driven churn drills 30 years ago could bore about 20 holes a day at 14 feet per hole to bedrock.
Churn drills were the standard method, and these were slow.