Blaster's Training Modules
Rotary drills work best in holes sized from 6 to 22 inches in diameter. Optimal hole depths range from 15 to 150 feet (typical) and average from 30 to 60 feet. Rotary Drill Rigs. Roller-cone or tricone bits are the most common bit used for rotary blasthole drilling. Bits have three or more cones ("rollers" or "cutters")—made with hardened ...