How to generate a special spindle M code for synchronous tapping?

Modern machines use a function that changes the amount of acceleration / deceleration during synchronous tapping based on the current spindle speed and the programmed feedrate. The M-code required to activate this function can be generated by the post-processor using two simple user-defined macros on the major word CYCLE.

The example below shows the technique required to output the M135 spindle code for a Makino machine.

1 Declaration Macro:
$$ Declare global variable for tapping
DECLAR / GLOBAL, REAL, SRPM=0 $$ Spindle RPM

2 User-defined Macros:

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Benefit to User
Synchronize the machine spindle speed and feed rate to match a specific thread pitch while driving a rigidly-mounted tap quickly in and out of the hole.

For more information or comments, please do not hesitate to contact Phil at TechTipTuesday@icam.com