Siemens SINUMERIK 840D sl Programming Manual page 249

Multiple thread
Multiple thread (thread with offset cuts) can be machined by specifying a starting point offset.
The programming is performed in the G33 block at address SF.
Note
If no starting point offset is specified, the "starting angle for thread" defined in the setting data
is used.
Thread chain
A thread chain can be machined with several G33 blocks programmed in succession:
Note
With continuous-path mode G64, the blocks are linked by the look-ahead velocity control in
such a way that there are no velocity jumps.
Fundamentals
Programming Manual, 09/2011, 6FC5398-1BP40-2BA0
9.10 Thread cutting with constant lead (G33)
Motion commands
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