DOUBLE JACK

 

MODERN DOUBLE JACK DRILLING

Today, double jack competitions are very similar to those of the 19th century. The main difference is the length of the competition.  Modern competitions are 10 min. in duration.  Whereas the historic competitions varied from 10-15 min. in duration. 

Another notable difference between the modern and older competitions is the position of the miners relative to the drill rock.  Historically the miners stood on the rocks that they drilled.  During large contests these rocks were placed on the street, and platforms were built around them to provide space for the drillers and event staff.

Today’s rocks are located at shin level.  Meaning that the miners do not have to lay down to shake, or bend over as far to hit the steel.

Much like the single-jack steels.  All double-jack steels are turned out of plain carbon steel. The diameter of the double-jack steel may not measure under 7/8” ( .875”).  Contestants are allowed as many steels as they can drill.  On average they increase 1.5” in length per steel. Hammers may not weigh in excess of 12lb.

Rocks used for contests are the same as those used in the single-jack competitions.

Like the single jack competitions, in double jack, there is an assistant spraying water into the hole to remove the chisel cuttings.


The modern record was set in 1993 by Scott Havens and Steve McDonald. In a 10-min. competition they drilled 26.9” in Creede Colorado.  They also drilled through the rock!     


Currently there is no World Championship for Double Jack Rock Drilling.

                                DOUBLE JACK

Double jack drilling referred to a two-man drilling team. One man holding the steel with his bare hands was known as the “shaker”.  His job was to hold the steel in position and then rotate it 90 degrees after every blow from the sledge hammer.  The other man known as the “driller” would swing an 8-12 lb. sledge hammer at the rock chisel being held in the shaker’s hands.  The driller’s job was to strike a firm blow, and never miss. 


“A 24-inch hole was generally considered a good depth in a ten-minute contest.” 

During a 15min. contest in Colbalt, Canada in 1909, a pair of double jackers drilled 43 1/8”- this, however, was not granite.” (The Sunday Camera, Sunday Feb. 13th 1977)


George Coughlin and Mick Coughlin were four-time world-champion double-jack drillers (1936-40) from Boulder, Co. George described the several advantages to their winning style:


“We used the slip handle technique. We would pick up the hammer and slip a hand onto the top of the handle, then throw the handle down. Everybody else kept their hands at the bottom of the handle and sort of chopped away. You had to start easy so you would get the hole going straight. Then when we’d get down 6-8 we’d begin fostering.”  Fostering meant that the man holding the steel would let go of it while he picked up his hammer to prepare to swing. Meanwhile the man drilling kept at it until his partner was in position to start. At the end of every 30 seconds they would change places. (The Sunday Camera February 20th 1977).

“No event of the day created more interest than the rock drilling.  The crowds surged so close to the drillers that they had to be repeatedly requested to move. They climbed onto the scaffold of the court house in such numbers that they had to be warned.  Many left because they could not see, but every time one left another took his place.”  Daily Camera

HAND DRILLING

Hand drilling is the archaic method used to drill holes into rock. The purpose of drilling the holes was to fill them with black powder.  When detonated, the black powder would fracture the rock into smaller pieces. This crumbled rock is referred to as muck.  The muck would then be hand-shoveled into mine cars and hauled from the breast of the mine, usually to the surface. Hopefully the muck contained ore. If so that ore would be sorted from the rock, and the metals the ore contained then extracted from the ore during the milling process.

Drilling contest in Eldora, CO 1900-1910. Courtesy of Denver Public Library

Drilling contest, Leadville Co 1890-1900.  Courtesy of Denver Public Library