Down-the-hole drill

The fast hammer action breaks hard rock into small cuttings and dust that are evacuated by a fluid (air, water or drilling mud).

This system used small diameter holes and was not only terribly inefficient, but very dangerous due to flying rock as a result of the inaccuracy of the drilled borehole.

In any event boreholes that are not aligned correctly which are then loaded with high explosive can be extremely dangerous, resulting in rock being projected beyond the intended site.

Larger quarries used big rotary machines that required huge amounts of down thrust and high rotation speeds to drive the tri-cone bit hard enough to crush the rock.

Another system in use was the very primitive cable tool machine (or bash and splash as it was known by the drillers) which caused a heavy bar and chisel to be lifted and dropped on the rock to crush it whilst water was introduced to create a slurry, which in the process, enabled the hole to be drilled.

It still offers the same benefits to the operator that it initially brought to the quarry industry but it is now being used in many different applications such as gold exploration, ground consolidation, geo-thermal drilling, shallow oil and gas well, directional and piling.

[5] DTH tools were used to locate the trapped miners in Chile and enabled food, water, and medicine to be passed to them and communication systems to be set up that eventually led to their safe rescue.