Version:
Helical fluted, with 4 guide chamfers and internal coolant holes. New generation of high performance co-pilot drills in the HPC range. With 138° point angle and special j6 cutting edge tolerance for optimum generation of a co-pilot hole. High roundness and alignment accuracy of the co-pilot hole.
Note:
Flute length L
C = L
2 + 1.5 × D
C.
To achieve good process reliability with 40×D and 50×D deep hole drills, it is absolutely essential to drill a pilot hole to the maximum drilling depth with a pilot drill No.
122736 and a 20×D co-pilot hole with a co-pilot drill No.
123691.
The generation of a pilot hole improves process reliability. See also pages 140/141.