Siemens SINUMERIK 808D ADVANCED Programming And Operating Manual page 77

See the following illustration for lead assignment for cylindrical, tapered and transversed thread:
Tapered thread
For tapered threads (2 axis values required), the required lead address I or K of the axis with the larger travel (longer thread)
must be used. A second lead is not defined.
Starting point offset SF=
A starting point offset is required for the spindle if a multiple-start thread or a thread in offset sections is to be machined. The
starting point offset is programmed in the thread block with G33 under the address SF (absolute position).
If no starting point offset SF is written, the value from the setting data "Starting angle of thread" is active (SD 4200:
THREAD_START_ANGLE) is active.
Please note: A programmed value for SF must always be entered in the setting data.
Programming example
Cylindrical thread, double-thread, starting point offset 180 degrees, thread length (including run-in and run-out) 100 mm,
thread lead 4 mm/rev.
N10 G54 G0 G90 X50 Z0 S500 M3
N20 G33 Z-100 K4 SF=0
N30 G0 X54
N40 Z0
N50 X50
N60 G33 Z-100 K4 SF=180
N70 G0 X54
N80 Z0
N90 G0X50Z50
N100 M30
Multi-block thread
If multiple thread blocks are programmed consecutively (multi-block thread), it only makes sense to define a starting point
offset in the 1st thread block. The value is only used here.
Multi-block threads are connected automatically in G64 continuous path mode.
Programming and Operating Manual (Turning)
6FC5398-5DP10-0BA2, 06/2015
; Approach starting point, clockwise spindle rota-
tion
;Lead: 4 mm/rev
; 2nd thread, offset by 180 degrees
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