bgolash,
How much weight do you have on you y axis? Depending on the amount of preload you will not be able to move an unloaded axis very easily. That is what I have discovered with some bearings I bought. These things are big enough to mount a car to, and with no wieght on them they are much more difficult to move. I can stand on one of them and it is like glass! Add some weight and see what happens...assuming you do have everything parallel.
Mike
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