HSS Steels with good machinability Rm < 750 N/mm² (101,500 PSI) Nodular graphite, Malleable cast iron
LAPPED THREAD: Gun-nose from M4 (M4 included), driving the chips ahead. 1.75 thread chamfer lead on both sides. Rake angle 15° - 17°. FOR TAPER THREADS: Unlapped thread. Without Gun-nose. Chamfer lead only on one side.
HSSE-V ( 3%V ) Heat treated and heat-resistant steels Rm < 1,000 N/mm² ( <30 HRC / <290 HB / <145,000 PSI )
LAPPED THREAD: Gun-nose from M4 (M4 included), driving the chips ahead. 2.25 thread chamfer lead on both sides. Rake angle 10° - 12°. FOR TAPER THREADS: Unlapped thread. Without Gun-nose. Chamfer lead only on one side.
HSS Stainless steels and structural steels Rm < 600 N/mm2 (<200 HB / <101,000 PSI)
HSS Short chip brass, Bronze
THREAD EXTRA LAPPED: Gun-nose from M4 (M4 included), driving the chips ahead. 1.25 thread chamfer lead on both sides. Rake angle 3° - 7°. FOR TAPER THREADS: Unlapped thread. Without Gun-nose. Chamfer lead only on one side.