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.
per hour; churn drills penetrated the limestone about 4 ft.
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.
A RotoSonic drill produces a similar sample size as the churn drill.
Drill samples from the initial 10 churn drill holes and the first four RotoSonic drill holes have been sent to SGS Lakefield in Canada for analysis and it is anticipated the first results from the drill holes will be available by mid-May 2010.
Phase 1 is a Banka or Churn drill program to delineate the extent and nature of the gravels at an estimated cost of US$350,000.
A total of twelve (12) large diameter churn drill holes, aggregating up to 500 meters total length have been recommended.
Deep churn drill hole results obtained by previous operators in the late 1950's indicate that the mineralization persists 200 metres below the level of the Gibraltar confirmation drilling.
To complete the drilling program, MGOL will be using two churn drills, two SonicSampDrill CRS-V drilling units with crawlers, and is under contract with SonicSampDrill to provide four additional drill masters to operate the CRS-V units.
Vintage drill hole logs show drill holes penetrated this cover but encountered intensely hard altered sedimentary rock (hornfels) that was too hard to be penetrated by the churn drills of the era.