Rotary axis configuration - unwind problem

I’ve added a rotary axis to my machine (the workpiece rotates like on a lathe), but I’m running into a problem when performing helical milling along the full length of the part. During the operation, the rotary axis accumulates a large number of degrees. Then, when the next operation commands the rotary axis to return to 0°, the machine tries to unwind all those rotations.What is the common solution for this issue? I can modify the post‑processor if necessary.

This is a common request, and the common solution is to add a G10 L20 command before any "reset" move, like this:

G10 L20 P#5220 A[#5423 MOD 360]
G0 A0.

That changes the WCS offset of the rotary by a suitable number of whole rotations, so that it's within one rotation of A0, without actually moving the rotary axis.

There is more discussion, and some proposed patches, at github.com/LinuxCNC/linuxcnc/issues/3902