SV04 problem at specific height

I made a model of a drinking glas, but 39cm high. In an online gcode viewer, the glas is perfect
GCode Viewer (

When i print this on my new SV04, at height +/- 26cm, their is a distortion

This first print had a second color logo on it.

Starting at height +/- 33cm the model is correct again.

I started a second print (now with only 1 color - left extruder), and it shows the same distortion starting at +/- 26cm
(I stopped this second print to save some filament)

Any idea what’s wrong?

Some ideas:

  • Check the gantry geometry (red lines should have equal distance).
  • Check that all bearing rollers on Z-axis can travel with equal pressure - if not use the excentric rollers to adjust.
  • Ensure that the travel paths of bearing rollers are free of obstructions & dirt (blue areas).
  • Check the geometry of the Z-axis threads (green): Ensure that the rods are not twisted by holding a ruler or any straight surface along whilst turning the Z-axis by Z-movement.

Thank you for your answer.

  • Gantry at the bottom is 2mm less wide than at the top.
  • bearing looks ok (what are the excentric rollers ??)
  • no dirt
  • green threads seem ok, but at the top they can wobble +/- 2mm in all directions. see this photo
    The red arrow shows the gap. The opening is +/- 2mm wider than this bearing.
    Schermafbeelding 2023-07-27 152416
    Is this space normal ??

As for the print itself, the error is completely around the print, not just 1 side.
I measured the distance at the red line: nearly 2mm.
Schermafbeelding 2023-07-27 151730

My suggestions: If you’re still within warranty write to Sovol, how they intend to fix that geometry problem of your gantry. Otherwise build such a piece of 2mm aluminum plate & insert it at the bottom between gantry and frame.

After fixing the gantry geometry adjust all bearing rollers on Z-axis. It is described on Page 3 “Eccentric Column Ajustment” in the SV04 Operation instruction that came with your SV04 SD-Card.
The play on top of the thread rods is common.

Another thougth: Maybe the distortions result from gantry vibrations at resonance frequencies.

Thank you very much for these suggestions.
I’ll report back when i’ve done this and tested it. And i will implement the rear frame braze you suggested. (already started printing the parts tonight)