'Bolt hole circle not coming out'

Doug Lien (208.123.31.138) -

We have a 98 VF3, the problem we are having is when we mill a cloverleaf shape the location of the 3 arc centers are off. We programmed it on mastercam and the program works in the 99 VF3. We then programmed a 3.5 bolt hole cirle and the bolt hole center came out at 3.508. But two hours later I ran the same program and it came out to 3.500. We had a new spindle and y ball screw put in. We also had a barball test done and got that within .0008. Any ideas what is wrong?

Comment #1 Toma (74.193.20.59) -

I think there could be a couple of issues here. I would look at the left side of the x axis ballscrew. I have seen on older mills the lock nut for the ballscrew will back off causing lose of motion. This should have been caught by the ballbar though. It could be simply the machine is not level. When you have a ballbar done you should be able to get it much closer than .0008".

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