Bit Rotation

The “RPM” of the drill string is important to achieve good percussion bit life and good penetration rates, over rotating can cause significant percussion bit damage whilst under rotation will affect the chip size of the sample and also penetration rates. When initially collaring a bit hole a rotation speed of between 40-50 rpm is recommended. Upon reaching the bed rock the following formula can be used as a starting point to determine the rpm required.

RPM = 154
bit size (in inches)