Mazak Mill Circular Interpolation problem

[DublJ]

I run a 91 Mazak AJV35/60 Milling center at work. Recently we have noticed that when circle milling or boring with an end mill that the hole is out of round. About .007" difference between X & Y. This occurred after we sent the Y axis servo to be repaired and reinstalled. I compared the parameters of the mill to the previous parameters before the repair and they matched. However I still think the problem is parameter related because the machine performs other positioning functions accurately. Does anyone know which machine parameter I should be looking at or have any insight on this problem?

[newguy81]

My M-2 machine do the same thing if I use the Mazatrol function. If I program in the manual unit it is fine. I asked Maszak in Kentucky a year ago at a class I took on M-2 and they said they didn't believe it. If you get it figured out let me know.

[psychomill]

Sounds like you need to bring someone in and have the servo(s) dialed in on a Ball-Bar. Never seen one go out that far but there are parameters that control the motor/screw movements. Is the problem just in certain areas of the machine or doesn't matter where? Does it change if you slow down or speed up? Does it change depending on the size of the arc? The answers to these may help to isolate the problem.

The issue with Nervis... I've seen that before too on the older controls. I always believed it to be comp related in some way. Never pursued the issue much though I'm almost always programming in G-code anyway (for mills).