Michael,

 

It sounds as though you have a little trouble with your axis lead screws. I don’t know the layout of your mill, but many mills have adjustment in the nuts to take out the free play.

 

Also, if you tighten up your gibs a tiny amount, that might prevent the table moving as much as you tighten up the locks. Or actually put your locks on, but not too tight, as you come to final setting. Then when you do the final lock tweak, it shouldn’t move so much.

 

If when you tighten up as it is now, anything under 0.05mm (0.002″) should be acceptable. That is a normal sort of tolerance figure, and isn’t usually noticeable on final assembly of parts made.

 

You can sometimes take getting perfection a little too far, and all you end up with is frustration, attempting to reach the impossible.

 

Bogs 

I am not sure if this will help but here goes.

I have recently completed a machining course at a local college and we used a simple but effective method for centring a rotary table on a vertical mill.  We measured the diameter of the centre hole and turned a piece of material down to fit it with a slight chamfer on the leading edge to aid fitment into the center centre hole, at the other end we turned it down to fit a collet.  We then fitted the alignment tool we had made into the appropriate collet in the mill head and adjusted the the rotary table until the tool fitted the centre hole of the table, then just to check, we rotated the table 360 degrees while the alignment tool was still in the centre hole of the table and the mill head rotated with it.  We then checked the set up and it proved to accurately aligned within the tolerances of the mill, so in future the set up can be repeated quite quickly and easily. Also the axis that are to be locked up can be done so while the alignment  toot is holding the table in location.