I've noticed that after my Anet A8 completes a print, the right hand Z mount ends up 1-2 mm lower than the left, even though I make sure both the left and right hand Z mounts of the X-axis are at the same height before switching on the printer.

Does anyone know what the cause of this might be?

I'm guessing something is causing the right hand Z to skip steps. I can't see or hear any obvious mechanical issues. I checked all guide and threaded rods were straight before assembly.

Could it be a faulty stepper or control electronics?

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    $\begingroup$ Try reuploading a firmware of your choice ( I prefer Marlin SkyNet3D version because it is preconfigured for the Anet A8). $\endgroup$
    – Tooniis
    Jun 9 '17 at 15:35
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    $\begingroup$ Duplicate of the other z-axis questions. $\endgroup$ Jun 9 '17 at 21:37
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    $\begingroup$ Possible duplicate of Alignment of dual Z-axis steppers $\endgroup$ Jun 9 '17 at 21:39
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    $\begingroup$ @SeanHoulihane - Hmmm, I thought this sounded familiar, when I reviewed it. However, your question is about the possibility of out-of-sync happening, and the answer offers no solution to this OP's issue (apart from the "levelling"). This question is looking for the cause, and, I guess, a definitive solution. $\endgroup$
    – Greenonline
    Jun 10 '17 at 4:18
  • $\begingroup$ This is one of the threads binding, due to bad alignment. Maybe I linked the wrong Q, there were 2 active when I experienced this. $\endgroup$ Jun 10 '17 at 9:01

My guess is your Z guides are not strictly parallel because there's no instruction how to install X guides correctly. When you install X guides, you can easily make horizontal distance between two Z-mounts either too small or too large, which puts extra stress on one of the Z motors. Move your extruder to home position, measure distance between bottom ends of Z threaded rods and between top ends, and try to adjust right Z-mount position on X guides so that these two distances become equal. Use hammer, but be accurate with plastic.


Try winding the Z axis all the up and down a few times using the front panel controls. Does it still go out of alignment? Is it out of alignment at the top? Does it come back into alignment when you wind it back down?

The principle is: if you have a dodgy motor drive chip, or a mechanical fault, it will skip some steps on the way up and the two motors will be out of synch. Then, on the way back down, it will skip an (approximately equal) number of steps and the motors will return to something resembling similar places.


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