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Old Haas VF0 1994, problem with jumping dimmension in Z axis


Feb 17, 2021
Hey everyone. I have another problem with my Haas, Z axis have counterbalance , and right now when i tunrn on program after machine make it all Z axis are higher almost 0,3mm.

I did program in MDI:

G90 G43
T01 M06
G00 Z30.
G04 P1
G00 Z150.
G00 Z30.
G04 P1.
G00 Z150.
G00 Z30.

In indicator after this program Z axis is 0,02 higher, if i turn on this program few times all Z axis move up almost 0,15mm.
If I zero Z axis it still have this 0,15mm incorrection.

So anyone have any ideas what happends ?

I don't understeand why when i zeroed Z axis they still have this incorrection, i think it should go back to correct position if they know when sensors are ?


Jul 6, 2006
Hillsboro, New Hampshire
I have no special knowledge of what may be wrong, but a some places to check are whether the coupling between the Z motor and ball screw is slipping, and if there's excessive play in the Z thrust bearing. A less-likely error source is a worn ball screw nut, or even less likely, worn linear bearing trucks.

After ensuring that the mechanical structures are all good, I'd start looking at the Z motor encoder. Hopefully others will have better ideas.