COUNTERBORES WITH 4 FLUTES

Counterbores with 4 flutes type N-N/T group 0-1-2 in HSS hardness 63 HRC, from Ø 7 to Ø 85.
Helix angle 40°. You can fit them in all the Polledri holders of the same group. These counterbores are manufactured
to solve all the problems of cylindrical head screw counterboring and spot-facing. With rotatory pilots
or drills you can execute simultaneous operations. We advise them for materials with short and normal chip.