When compared with ordinary drill heads with rotating bits, the BDA will cut up to twice the footage daily in soft shales, clays, shells, soft limestone, red beds and other rocks of low compressive strengths. In addition, it offers the following important features:
- "Step" drilling pattern for fastest penetration.
- BD-2 Bits.
- Twin bits on outer surface for added protection.
- No independent moving parts to become clogged.
- Requires only a moderate weight for full effectiveness.
- Precision machined head.
- Durable, trouble-free.
- 6 sizes for drilling holes from 4½" to 1015/16".
- Choice of 23/8", 27/8", 3½" and 4½" API shanks. Other threaded shanks on request.
|
Cutaway sketch of step drilling pattern as cut by Blue Demon BD and BDA Drill Heads. Lead bit drills 1½" hole. It is followed by other bits that shear and ream final hole size. Bits are set at an angle to assure fastest penetration without scaping, chipping or gouging
|
Drilling blasthole with Blue Demon BDA Drill Head.