Rockbit "Weight on Bit" and "RPM" Operating Suggestions

4-1/2" API Regular Pin Connection


Weight on Bit per Inch of Bit Diameter Total Suggested Weight on Bit (Pulldown Force)
IADC Class RPM Low High 6 3/4" Bit 7 7/8" Bit 8" Bit
1-1 to 1-4 70 to 120 1,000 3,000 20,250 23,625 24,000
2-1 to 2-4 60 to 100 3,000 5,000 33,750 39,375 40,000
3-1 to 3-4 60 to 80 4,000 7,000 47,250 55,125 56,000
4-1 to 4-4 50 to 150 1,000 5,000 33,750 39,375 40,000
5-1 to 5-4 50 to 150 3,000 6,500 43,875 51,188 52,000
6-1 to 6-4 50 to 120 4,000 7,000 47,250 55,125 56,000
7-1 to 7-4 50 to 90 4,000 8,000 54,000 63,000 64,000
8-1 to 8-4 40 to 80 6,000 9,000 60,750 70,875 72,000

4-1/2" API Regular Pin Connection


Weight on Bit per Inch of Bit Diameter Total Suggested Weight on Bit (Pulldown Force)
IADC Class RPM Low High 8 1/2" Bit 9" Bit
1-1 to 1-4 70 to 120 1,000 3,000 25,500 27,000
2-1 to 2-4 60 to 100 3,000 5,000 42,500 45,000
3-1 to 3-4 60 to 80 4,000 7,000 59,500 63,000
4-1 to 4-4 50 to 150 1,000 5,000 42,500 45,000
5-1 to 5-4 50 to 150 3,000 6,500 55,250 58,500
6-1 to 6-4 50 to 120 4,000 7,000 59,500 63,000
7-1 to 7-4 50 to 90 4,000 8,000 68,000 72,000
8-1 to 8-4 40 to 80 6,000 9,000 76,500 81,000

6-5/8" API Regular Pin or BECO Connection


Weight on Bit per Inch of Bit Diameter Total Suggested Weight on Bit (Pulldown Force)
IADC Class RPM Low High 9 7/8" Bit 10 5/8" Bit 11" Bit
1-1 to 1-4 70 to 120 1,000 3,000 29,625 31,875 33,000
2-1 to 2-4 60 to 100 3,000 5,000 49,375 53,125 55,000
3-1 to 3-4 60 to 80 4,000 7,000 69,125 74,375 77,000
4-1 to 4-4 50 to 150 1,000 5,000 49,375 53,125 55,000
5-1 to 5-4 50 to 150 3,000 6,500 64,188 69,063 71,500
6-1 to 6-4 50 to 120 4,000 7,000 69,125 74,375 77,000
7-1 to 7-4 50 to 90 4,000 8,000 79,000 85,000 88,000
8-1 to 8-4 40 to 80 6,000 9,000 88,875 95,625 99,000

6-5/8" API Regular Pin or BECO Connection


Weight on Bit per Inch of Bit Diameter Total Suggested Weight on Bit (Pulldown Force)
IADC Class RPM Low High 11 1/2" Bit 12 1/4" Bit 13 3/4" Bit
1-1 to 1-4 70 to 120 1,000 3,000 34,260 36,750 41,250
2-1 to 2-4 60 to 100 3,000 5,000 57,100 61,250 68,750
3-1 to 3-4 60 to 80 4,000 7,000 79,940 85,750 96,250
4-1 to 4-4 50 to 150 1,000 5,000 57,100 61,250 68,750
5-1 to 5-4 50 to 150 3,000 6,500 74,230 79,625 89,375
6-1 to 6-4 50 to 120 4,000 7,000 79,940 85,750 96,250
7-1 to 7-4 50 to 90 4,000 8,000 91,360 98,000 110,000
8-1 to 8-4 40 to 80 6,000 9,000 102,780 110,250 123,750

6-5/8" API Regular Pin or BECO Connection


Weight on Bit per Inch of Bit Diameter Total Suggested Weight on Bit (Pulldown Force)
IADC Class RPM Low High 15" Bit 16" Bit 17 1/2" Bit
1-1 to 1-4 70 to 120 1,000 3,000 45,000 48,000 52,500
2-1 to 2-4 60 to 100 3,000 5,000 75,000 80,000 87,500
3-1 to 3-4 60 to 80 4,000 7,000 105,000 112,000 122,500
4-1 to 4-4 50 to 150 1,000 5,000 75,000 80,000 87,500
5-1 to 5-4 50 to 150 3,000 6,500 97,500 104,000 113,750
6-1 to 6-4 50 to 120 4,000 7,000 105,000 112,000 122,500
7-1 to 7-4 50 to 90 4,000 8,000 120,000 128,000 140,000
8-1 to 8-4 40 to 80 6,000 9,000 135,000 144,000 157,500