Siemens SINUMERIK 840Di sl Programming Manual page 166

Motion commands
4.15 Thread cutting with constant lead (G33)
I (taper thread)
I... or K...
SF=
Example of double cylinder thread with start point offset
Machining a double cylindrical thread in offset steps with starting point offset 180°.
N10 G1 G54 X99 Z10 S500 F100 M3
N20 G33 Z-100 K4
N30 G0 X102
N40 G0 Z10
N50 G1 X99
N60 G33 Z-100 K4 SF=180
N70 G0 X110
N80 G0 Z10
N90 M30
166
Lead angle >45°, thread lead in transverse direction
I or K can be stated at thread lead = 45°
Starting point offset, only needed for multiple threads
;Zero offset, approach
;start point, spindle on
;Cylindrical thread: end point in Z
;Retract to starting position
;2. cut: Starting point offset 180°
;Retract tool
;End of program
Programming Manual, 11/2006, 6FC5398-1BP10-2BA0
Fundamentals