When the X coordinate was zero, the axes of the spindle and the rotary table were not coplanar, and the rotary table could not be used for precise machining.
Fixed two fixtures on the rotary table, as shown in the picture. While the rotary table turned to 0° or the B axis was in 0° position, made them parallel to the Z axis with a dial gauge. Found the center coordinate between the two fixtures through touching, reading and calculation:
while B=0°, X=-151.010;
while B=180°, X= 151.236.
Added this 0.113 to the value of the 34090# parameter (REFP_MOVE_DIST_CORR, 456.977+0.113=457.090) and restarted the machine. Found the situation was improved.
The difference between the absolute values of the positive and negative X could be very small when the process is repeated. Finally it was 5μ in this example.