NDS Drilling Supply

SOFT TO MEDIUM SOFT FORMATIONS
NDS offers the 5-2-1 design for efficient drilling of soft to medium formations such as shale, red bed, limestone and other strata of low compressive strength with hard streaks or abrasive properties. This design employs a maximum offset and features all chisel shaped tungsten carbide inserts which are spaced slightly farther apart than normal to insure the highest possible rate of penetration. Ample hard facing on the shirttail provides maximum protection against abrasion and insures the longest possible bearing life. Suggested operating weights are 1,000 to 3,000 pounds per inch of bit diameter with corresponding rotary speeds of 200 to 50 RPM.

MEDIUM HARD FORMATIONS
The 6-3-1 is designed for medium hard formations that are semi-abrasive such as hard, sandy limestone, shale, dolomite and limestone with cherty streaks. This design features conical shaped tungsten carbide inserts on the gage rows to inhibit gage wear and chisel shaped inserts on the inner rows to get maximum penetration. Gouging/scraping action is provided by cone offset. Ample hard facing on the shirttail provides maximum protection against abrasion and insures the longest possible bearing life. Suggested operating weights are 1,500 to 6,000 pounds per inch bit diameter with corresponding rotary speeds of 140 to 55 RPM. Near the bit stabilization is recommended for maximum bit life.

MEDIUM HARD TO HARD FORMATIONS
The 7-4-1 features a minimum offset cutting structure design and all dome shaped tungsten carbide inserts. It is designed to drill hard and abrasive formations such as quartzite, granite, cherty iron ores, and copper porphyry. As with other NDS bit designs, this design features shirttail hard facing for maximum resistance to bearing wear. The drilling weights should range from 1,500 to 8,000 pounds per inch of bit diameter. As drilling weights are increased the rotational speed, which ranges from 120 to 50 RPM, should be decreased. Near the bit stabilization is highly recommended for maximum bit life, and pull down drills should be equipped with shock absorbers.