Subland twist drills for holes prior to tapping screw threads
The drills are designed to produce holes prior to tapping metric threads (coarse pitch series) over a selected range of:
- M8 to M30 for subland twist drills with Morse taper shanks;
- M3 to M14 for subland twist drills with cylindrical shanks.
ISO 3438:2013 complements ISO 2306.