Drill string vibrations

The existence of substantial vibrations in the drillstring have caused much trouble time during drilling in slim (and conventional) holes. Minimising drillstring vibrations during the drilling of slim…

Mechanical power to the bit / corehead

This article describes  the various ways of transmitting mechanical power to the bit by rotation. There must be sufficient HHP at the bit to keep the cutters or diamonds clean, and that an…

Mechanisms of rock cutting

Bits and coreheads cut rock by crushing, shearing, grinding or jetting. Crushing bits are the well known roller cone bits and hammer bits.

1 Crushing bits - roller cone rock bits

Crushing bits work by…