HSSE ( 3%V ) Heat treated and heat-resistant steels Rm < 1,000 N/mm² ( <30 HRC / <290 HB / <145,000 PSI )
Handtap No. 1 with pilot guide, to assure the concentric start at manual threading.
Tapping only 3-4 threads is enough. 3 thread chamfer lead. Rake angle 6° - 8°.
Handtap No. 2 with the same thread sizes as 108/1.
3 thread chamfer lead. Rake angle 6° - 8°.
Handtap No. 3 that finishes the thread to the required tolerance.
Not suitable to use as single pass tap. 3 thread chamfer lead. Rake angle 6° - 8°.
Handtap set consisting of 3 taps:
108 = 108/1 + 108/2 + 108/3. You must tap continuously, it means without stop and reversing the tap to break the chip.