It is possible that your gibs are too tight. The ways are worn and dished. Thus more force is necessary to move the Y axis where the saddle is tight and you measure more backlash as the bearings and associated parts take this additional force.
I do not advise you to shim the bearing. The proper solution is to refurbish the ways.
George
__________________
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
|