Z-Axis raising and dropping substantially during print knocking print off


I've had my Creality Ender 3 Pro since October 2019. It was running like a dream until about a month ago. The Z-axis started knocking prints off the plate during printing. I've changed mats and worked on adhesion issues. I've switched to a glass plate and triple checked that it is level. I checked to see if it was binding but honestly I couldn't tell.

I'm at a loss of what to do to troubleshoot and fix the issue. Any suggestions?

It homes fine and manual controls work fine with no issues.


Posted 2019-12-23T13:39:19.337

Reputation: 21

Welcome to 3dPrinting.SE! – Pᴀᴜʟsᴛᴇʀ2 – 2019-12-23T19:44:16.060

1Can you explain what you mean by the "Z axis knocking prints off"? What part actually collides or moves in a manner that's unexpected/erroneous? – R.. GitHub STOP HELPING ICE – 2019-12-23T20:03:14.633

can you check if your Potal (X-Axis) is orthogonal to the vertical bars? knocking it off is a known issiue. – Trish – 2019-12-25T19:02:05.403

Did you ever find out what happened? Please add an answer if you did! – Jason – 2020-08-17T12:33:23.623

did you get an answer to this? I'm having the same issue and the z axis keeps dropping during prints at regular intervals above a certain height, as if it can't hold itself up (all screws seem to be right, and there's no binding it just isn't holding itself at the right height)? – Willow – 2021-01-09T10:18:12.877



Can you send a link to a short video of the problem occuring? It might be because of multiple factors but we will be able to identify if there's a video of it.

Possible reasons:

  • Z axis nut might be too tight. This would cause the nut to bind with the leadscrew and so the motor will not be able to lift the z-axis further while printing.

  • Not enough retraction. This would cause filament to ooze from the nozzle during travel moves and this filament would collide with the printed object, causing it to be knocked off. A possible solution for this would be to enable Z-hop in the slider, have the hop distance set to at least 1.5x the layer height you are currently printing with.

  • Too small of a contact area. This usually happens more often for tall prints. A solution would be to increase brim in the slicer settings (at least 10~15 lines) to increase the adhesion of the print and the bed.

  • Dirty nozzle. Old prints filament may be stuck on the outer face of the nozzle and might be catching onto the printed part while printing.


Posted 2019-12-23T13:39:19.337

Reputation: 21