Quote Originally Posted by mactec54 View Post
This would have shown up in the Ball-Bar test, I would say your machine has moved or it was not level to start with, the machine needs to be leveled in all both directions

Did you reverse the level to see if it has the same reading
It wasn't the actual measurement that I was interested in, more so the change across the travel. The machine was only levelled last week and hasn't been used for machining yet. I did however calibrate my level beforehand. Bear in mind this is a very sensitive level - 0.02MM per 100CM. On a more typical level it does show basically perfect measurements.

What would it have shown up as? Squareness error?