The Z motor does not work properly randomly

[swq0603 1]

Now I am hitting a strange issue. My machine is the ultimaker go. I set the layer to 0.1mm. When the printing start, the Z motor should make the plate go down 0.1mm each time, but I find the plate go down >0.1mm randomly, which make the the full printing failed. Anyone hit the similiar issue? Thanks in advance!

[swq0603 1]

Not sure it is caused by the EMI. Nobody hit the similiar issue？

[peggyb 171]

maybe this thread can be helpful:

https://ultimaker.com/en/community/23246-z-axis-repeatability-problem

[gr5 2,268]

A photo of your print would help. If the movement is small (an extra 0.1mm) then it's almost certainly z screw, z nut, z bearings, or z rods.

If the movement is > 1mm then it's almost certainly your stepper driver is overheating. There is discussion about this on the forum somewhere. UM released a solution to lower the current to the z driver only. Another solution is to remove the bottom cover and tilt your printer and put a fan blowing under there. At least to test to see if this is your issue.

Maintenance -> Advanced -> Motion settings -> Current Z

Ultimaker lowered the default currents in July of 2015 from 1300ma to 1200ma for X,Y,Z but left extruder at 1250. Other people (I think the support team of a major reseller but I forget) recommend X,Y,Z go down to 1000mA.

If you don't have control over current in the gui reply back here. You can do it through gcodes.