Is it possible for Z axis to lose position over time?

Machines (Original/PRO) Troubleshooting (X35/X50)
1

Just wondering is it possible for the Z axis to lose position over time or after the machine has been pause? if this happen what would be the potential cause?

Henry

2

I would say unlikely, but possible nevertheless. The Z could be subject to downward creep based on the weight of the assembly, without power to the motor. Much the same way you can manually move X & Y with no motor power, the z has the weight working to drive it downward.

3

Yes, it is possible.
The controller estimates the position from the moves but the motors are not servos so there is no feedback. If a move does not perform as planned, then an axis would loose position.

Prior to firmware 1.0.8, this could happen when the G-code was requesting moves faster than the machine could achieve. I also had the problem on the Y axis with a badly placed wrench that blocked a move. It lost position but carried on milling… in the wrong position.

I can imagine that hard stock that does not machine as quickly as planned could cause the Z axis to loose its position, although I never had the problem myself.

4

"Prior to firmware 1.0.8, this could happen when the G-code was requesting moves faster than the machine could achieve. "
Is there a thread talking about this? I have had this issue happen several times over the last few months losing position and then continuing on in new position but have not seen any real solution found. I looked for loose parts or bent screws but could not find any reason for it.

5

I have not seen it in a single thread.
The firmware 1.0.8 change log discusses the controller loosing steps:

@blaghislain explained the problem with the firmware and fast moves, after I had requested help with Fusion 360 CAM.
If you google servo vs stepper, you will see that the 1F controller has no feedback from the motors.

6

Thanks for the info. I am using carveco so I am not sure if my issues are the same. It has only happened a few times over the last few months but each time was during a very long detailed carve for me.

7

Should not happen if the motors remain powered. Has happened to me after a bone head mistake like probing without the magnet :wink: Or drilling on a screw head. The stepper would have to lose a step for it to get out of sync.