Pneumatic Rock Drill

Pneumatic Rock Drill. (Jackleg Drill). The pneumatic rock drill, also called a jackleg drill, was the most versatile rock drill used at the Homestake Mine and mines worldwide. This drill was used to drill holes that were then loaded with explosives for blasting and to drill holes that were then used for ground support (rock bolts). Compressed air actuated both the rotation and penetration rates of the drill and water was used to both cool the drill bit and remove the cuttings. A special oil was used to lubricate the internal workings of the drill. , The drill was hand-operated and could be moved around the mining areas on a regular basis, sometimes into 3-4 different areas in one shift. The drill and the telescoping leg are two components that could be replaced individually in case of a failure. The drill and leg weigh approximately 135 pounds in total. , Different lengths of drill steel would allow various hole depths to be drilled. A typical drill hole depth for production was 10 feet, with approximately 35-40 holes needed in a 10 foot by 10 foot square face. When blasted this would result in approximately 90-100 tons of ore. Other hole depths were used for rock bolts and geologic sampling. Different diameters of drill bits also increased the versatility of the jackleg drill.