Pax-Set Core Bits (R-Pax, T-Pax, H-Pax)

Pax-Set core bits are supplied with large cylindrical PCD elements mounted in a matrix body bit crown. The ‘R-Pax’ style uses a fully round cutter while the ‘T-Pax’ and ‘H-Pax’ styles use cylindrical cutters that have been truncated to provide stronger gauge definition. The gauge diameter surfaces are set with a combination of natural diamond and tungsten-carbide pads. Additional TSP elements are set on the gauge diameter surfaces of all ‘R-Pax’ core bits. For heavy-duty applications, the ‘T-Pax’ style is recommended in place of the ‘H-Pax’ style as the ‘T-Pax’ cutters are physically larger and as such possess a larger surface area for anchoring within the bit crown matrix body.

In order to efficiently eject the large cuttings generated by Pax-Set bits, the standard waterway configuration is the face-discharge type with slot-shaped ports (Style ‘SFD’). Most Pax-Set bit designs also include junk slots on the outside gauge diameter for enhanced cuttings ejection.

Pax-Set core bits are recommended for use in softer unconsolidated formations with a Mohs hardness range of 2 to 3. Typical formation types include: Soft Sandstone, Calcite, Lignite, Frozen Soil, Sandy Limestone, Hard Clay, Shale and Soft Schist.

For optimum performance, Pax-Set core bits require a bit load of approximately 500 to 600 lbs. force (2,200 to 2,700 N) per Pax (PCD) cutter mounted on the bit face. Always verify that the calculated bit load value does not exceed the load bearing capacity of the drill string in use. A rotational speed of 2 to 5 feet per second (0.6 to 1.5 metres per second) measured on the outside diameter of the bit crown will provide an acceptable rate of penetration.

TSP-Sawtooth Core Bits

As the name suggests, this type of core bit has an aggressive saw-tooth pattern moulded into the face of the bit crown matrix body. Triangular TSP elements are embedded into the leading edge of each saw-tooth segment. The gauge diameter surfaces on all TSP-Sawtooth core bits are set with a combination of natural diamond and tungsten-carbide pads.

Due to the friable nature of the formations for which these bits are intended, all TSP-Sawtooth core bits are supplied with the slot-style face-discharge waterway configuration (Style ‘SFD’). Wide channels are moulded into the outside diameter of each saw-tooth segment to efficiently discharge the cuttings and circulation fluid from the bit crown.

TSP-Sawtooth core bits are recommended for use in very soft unconsolidated formations with a Mohs hardness range of 1 to 2. Typical formation types include: Plastic Clay, Gypsum, Talc, Marl, Sand and Soft Shale.

Relatively low bit loads are required for TSP-Sawtooth core bits. Some on-site experimentation may be required to establish an effective bit load setting due to the variable nature of the formations being drilled as well as the potential for overfeeding the bit. Very low rotational speeds in the range of 1 to 3 feet per second (0.3 to 0.9 metres per second) measured on the outside diameter of the bit crown will generally provide an acceptable rate of penetration.