Drills type C-L group 0-1-2 in HSS hardness 63 HRC from Ø 4,2 to Ø 25.
You can fit them in all the Polledri holders of the same group. Fitting them
in the counterbores and countersinks you can to drill and to counterbore or
to countersink simultaneous. Using a good soluble oil you can increase the
speed, with an increase of the tool life.
On each counterbore it is possible to mount a pilot or a drill,
in this second case, the tool can only work through holes and not blind holes.
The length of the tip propeller must be such that it comes out of the hole
before the counterbore starts working.