Is anyone here successfully using a stepper spindle for thread cutting?

[spxwh]

Is anyone here successfully using a stepper spindle for thread cutting? I noticed that the thread lines don't overlap each time when I'm trying to cut threads. I am using a stepper spindle and have enabled the lathe mode ,and $677=3.Thank you.

[terjeio]

Is this with the modifications you made? If so did you modify spindleGetData() to match?

[spxwh]

I previously modified the parameter definitions for the stepper spindle. After the problem occurred, I restored the parameters to their original values, but the test results still showed that the thread phase was different each time (the starting points of the threads did not overlap).
The mechanical part should be fine, as I can cut correct threads with other controllers.
The spindle speed measured with a tachometer is correct.
Testing with the command A100F200 also confirmed that the servo spindle stops at the initial marker position after rotating 100 revolutions, proving there is no error in the servo spindle.
Can I enable the following test definition to print the phase of the starting position for each cycle of the G76 command?How can i printf the message. Just #define DEBUGOUT=1?

#ifdef DEBUGOUT
#define ST2_DEBUG 0
#else
#define ST2_DEBUG 0
#endif

[spxwh]

Problem resolved. The variable offset assignment of the stepper spindle in your program lacked phase alignment. Test passed.

[terjeio]

The variable offset assignment of the stepper spindle in your program lacked phase alignment.

Interesting, what did you change?

[spxwh]

static void spindleDataReset (void)
{
int64_t steps_per_rev = (int64_t)(settings.axis[axis_idx].steps_per_mm * 360.0f);
int64_t current_pos = st2_get_position(motor);
int64_t phase = current_pos % steps_per_rev;

offset = current_pos - phase;

}