Underground Report: Ditch Witch All Terrain Air Hammer Takes On Hardest Rock
The Ditch Witch range of All Terrain horizontal directional drills was developed, says the company, to allow drilling effectively in a wide range of ground formations, from mixed hard soil, to cobble, to solid rock. To further expand the capability of All Terrain drills, Ditch Witch has now developed the All Terrain Air Hammer, which is designed for use with the JT4020 or JT100 All Terrain drills when working in extremely hard rock formations—those with compressive strengths of 20,000 to 35,000 psi or more.
Ditch Witch All Terrain drills feature a patented “shaft-within-a-pipe” drill string, and the machine independently powers both an inner shaft that drives the cutting bit, as well as an outer pipe that is used for steering and back-reaming. For the larger JT4020 and JT100 models, the inner shaft has a central passage that channels airflow to the Air Hammer. According to Ditch Witch, the design of the All Terrain drill string allows the Air Hammer to drill continuously as it is being steered.
The Air Hammer does not require an oiling system or drilling mud, says Ditch Witch, although some situations might require a foaming agent in the water. The Air Hammer operates at a low fluid-flow rate (4 gpm), and used properly, says the company, it leaves behind only dry cuttings and a relatively small amount of fluid. Air consumption for the Air Hammer is listed in Ditch Witch specifications as 970 cfm at 350 psi.
The Air Hammer is available as a kit that includes the hammer, 6.5-inch convex bit with spherical inserts, convex-bit jaw, 4-inch jaw assembly, two slide pins, Rockmaster air housing, fluid pump, and air-adapter kit. According to Ditch Witch, the Rockmaster air housing features large ports that promote optimum performance.
In a video created by a California Ditch Witch dealer, the new Air Hammer is shown drilling through 8 feet of granite in 6.5 minutes. Watch the demonstration.
