For HSS & Carbide Tipped Counterbores. The shank diameter ordered must be the same as the pilot hole diameter in the counterbore to be used.
The pilot diameter is always larger than the shank diameter and is determined by pilot hole.
Pilot Diameter:
1/8" to 1/4" - 0.001" - 0.002"
9/32" to 7/8" - 0.003" - 0.004"
15/16" to 1-1/8" - 0.005" - 0.006"