Siemens SINUMERIK 840D sl Programming Manual page 231

Further information
Sequence of motions
1. Approach starting point
2. Execute the full circles programmed with TURN=.
3. Approach circle end position, e.g. as part rotation.
4. Execute steps 2 and 3 across the infeed depth.
The pitch, with which the helix is to be machined is calculated from the number of full circles
plus the programmed circle end position (executed across the infeed depth).
Programming the end point for helical interpolation
Please refer to circular interpolation for a detailed description of the interpolation parameters.
Programmed feedrate
For helical interpolation, it is advisable to specify a programmed feedrate override (CFC).
FGROUP can be used to specify which axes are to be traversed with a programmed feedrate.
For more information please refer to the Path behavior section.
Fundamentals
Programming Manual, 09/2011, 6FC5398-1BP40-2BA0
Motion commands
9.7 Helical interpolation (G2/G3, TURN)
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