Siemens sinumerik 808d Programming And Operating Manual page 178

Cycles
2.5 Turning cycles
The cycle creates the following sequence of motions:
● Approach of the starting point determined in the cycle by using G0
● Selection of the tool radius compensation according to the active tool point direction.
● Retraction to the starting point with G0 and deselection of the tool radius compensation
Explanation of the parameters
DIATH (nominal diameter)
Use this cycle to perform thread undercuts for metric threads from M3 through M68.
If the value programmed in DIATH results in a final diameter of <3 mm, the cycle is aborted
and alarm:
61601 "Finished part diameter too small" is issued.
If the parameter has a value other than specified in DIN76 Part 1, the cycle is also canceled,
generating the alarm:
61001 "Thread lead defined incorrectly".
SPL (starting point)
The finished dimension in the longitudinal axis is defined using the parameter SPL.
FORM (definition)
Thread undercuts of the forms A and B are defined for external threads, form A for standard
run-outs of threads, and form B for short run-outs of threads.
Thread undercuts of the forms C and D are used for internal threads, form C for a standard
run-out of the thread, and form D for a short run-out.
178
Traversing along the undercut contour using the feedrate programmed before the cycle
was called
with G40
Turning Part 2: Programming (Siemens instructions)
Programming and Operating Manual, 05/2012, 6FC5398-5DP10-0BA0