The
components
Driver bit
The driver bit is the device that transfers impact and rotation to the crown bit for drilling. The driver bit locks into two flats on the casing crown and they act together as a standard drill bit, both the driver bit and the crown have tungsten carbide buttons. The Driver bit drills a pilot hole of 3″ below the crown to guide the direction of the casing in rough drilling.
Ring bit
The crown bit is a single unit with Tungsten carbide, held on the driver only by the locking surface.
Driving shoe
The driving shoe is welded to the casing and receives the impact from the driver bit to drive down the casing. The drive shoe is the same OD as the casing to allow easy retrieval.
- Impact zone: Direct energy from the hammer is transferred to the Ring bit through two (2) recesses formed by the locking surface plus a projection all around the periphery of the driver (donut).
- Evacuation: Two (2) big air holes are drilled in the face of the bit (drilling end). Those holes are directly connected to two (2) large flushing air ways, these flushing grooves transfer the drill debris from the drilling end of the driver up to the hammer zone. To help keeping a good flow of debris, two (2) other smaller air holes in the flushing air ways, help give the cuttings some velocity.