Gentlemen,
Last Saturday I discovered a major out of square condition on my Haas VF10.
I explained it in another thread but I thought a separate thread would be appropriate. Here is a copy of the post in the other thread.

Hi,
I just discovered an out of square condition on my three Haas mills. I have a VR11, a VF10 and a VF6. All three are out of square between X and Y. Inspection found an out of square hole pattern on a large plate machined on the VF10.
The VF10 was .340 in 120 inches.
The VR11 is .052 out of square in 120 inches.
The VF6 is .007 out of square in 60 inches.
The VF10 X axis linear guides were recently (within a year) replaced by Haas. The linear guide replacement was NOT the cause of the out of square condition. The linear guide replacement was a simple task and is difficult to get wrong because of the design.
A square artifact would allow an accurate check of squareness - the larger the better. To check squareness align one leg of the square with either the X or Y and check the other leg for runout. My solution was to set up a laser tracker to check and adjust the squareness.
The adjustment procedure is simple.
Set up whatever inspection device (square or tracker)
Pull back all of the XY way covers.
Loosen the linear guide trucks carrying the saddle (Y axis).
Push/pry the X axis square.
Tighten the trucks.
We also loosened the Y axis ball nut to allow repositioning along the axis of the ball screw.
We now have the VF10 X axis square with .002 in 120 inches.
Now we will address the VR11 and VF6.