Z axis moving down on vmc 6030

[bedfordia]

We are having a problem with our 6030. The operator adjusts the cold start position on startup. The machine runs fine and makes tool changes for the first 10 to 15 minutes. when we start having trouble is on a tool change. the tool carousel will hit the tool and jam up. the z axis seems to settle downward after a few minutes of running. we can rehome the machine and start over, it will run ok for a few minutes and jam again. does the z axis motor have a motor brake? if not what could cause the z axis to inch down on it's own?

[Neal]

I would check the servo motor and/or DC resolver or AC encoder which ever you have. If it is just drifting down, it might be loose gibbs and straps. You need to id if it is being driven down by the motors or just slipping by gravity.

Neal

[brandpeto]

Check the bearings on the sprockets/chain that the counterweight for the z head ride on. Right in front of Z axis servo. I had a similar problem on our 8030. The Z head would drop a few thou. when it was in jog mode.. the bearings were totally shot. replaced em and it resolved the problem.