How to solve the problem of obvious shifting when the CNC machine tool falls after indexing

Trouble phenomenon: A CNC machine tool equipped with FANUC OMC, model XH754, when the rotary table is indexed, it will move obviously and fall loudly.

Analysis and processing process: when the turntable is indexed, the shift is obvious when it falls, indicating that the index position of the turntable is quite different from the positioning position of the spur gear; if the position is also shifted at the same time, the grid offset of the 4th axis can be adjusted (Parameter 0511) to solve: If the turntable transmission has a gap, you can adjust the fourth axis gap compensation (parameter 0538); if the mechanical pitch is in error, adjust the fourth axis screw compensation accordingly. In this example, it was found that the turntable also moved incorrectly after returning to zero. Adjust the value of 0511 to solve.