Rotary speed selection chart

Bit type	Impregnated core bits	Increase the speed
Bit type	Surface set core bits	Decrease the speed
Bit diameter	Small bit diameter	Increase the speed
Bit diameter	Large bit diameter	Decrease the speed
Peripheral velocity	High velocity	Decrease the speed
Peripheral velocity	Low velocity	Decrease the speed
Rock properties	Hard and complete	Increase the speed
Rock properties	Soft and broken	Decrease the speed
Diamond	Large size	Increase the speed
Diamond	Small size	Decrease the speed
Drilling equipment and core barrel	Good stability	Increase the speed
Drilling equipment and core barrel	Poor stability	Decrease the speed
Drilling depth	Shallow hole	Increase the speed
Drilling depth	Deep hole	Decrease the speed
Structure of boreholes	Simple structure	Increase the speed
Structure of boreholes	Complicated structure	Decrease the speed