... bit,single cone bit , reamer bit,down hole opener,hole enlarger,drag bit,button bit and drilling equipment ... and tectonic industries ,oil field, construction, geothermal, directional boring, and underground foundation work all over the world. 2> ... call) .Recommended drilling parameters of tri-cone rock bits Rock formationBit typeBit sizeDrilling weightRotary speedmminchkN/mmr/minVery softSoft Marl ...