Coolant Hole Configurations
Coolant hole configurations play a critical part in the gundrill selection process. Coolant systems that lack adequate pressure or volume would benefit from the single oil hole. The single orifice allows more PSI with less volume. Systems with ideal PSI and GPM should run either a Kidney (.075″ – .3174″) or Dual (.3108″ – 1.520″) oil holes for greater chip evacuation and coolant to the cutting edge.