COUNTERBORES WITH 4 FLUTES in HSS HRC 63 from Ø 7 to Ø 24.
You can fit them in all the Polledri mandrels 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.