what causes this gap ? (Prusa Slicer) 30$ reward

I do have issues with my printer or slicer settings. I am getting a concave gap

mostly at the same position and I don´t know how to remove it

the foto looks worse because of the light. my only concern is the gap (red arrwows)

the filament is a petg and my slicer is Prusa 2.6. ( I have to use this 2, so orca slicer .... is not an option)

my guess is the transition from perimeter with infill to only perimeter lines



I will give a reward of 30 US Dollar with pay pal to whoom solves the problem

gcode link to file
[drive.google.com]

Looks like it might be a z axis problem. If the Z axis doesn't move the full layer distance, the plastic will be squished outward and lines will be fatter than they should be. If it moves more than the full layer distance lines will be narrower than they are supposed to be.

Another possibility is that the extruder carriage is shifting - does the concavity go all the way around the print, or does it appear on one side with an overhang on the other side?

What is the printer? What sort of Z axis drive does it have (belt, screw?), what is print layer thickness?

If you make multiple prints- one at a time, do they all come out with the same grooves in the z axis? If you make multiple prints at the same time do they all look the same or are they different?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I will check your suggestions with prints.

but the concave gap is indipendend of the object position

z axis is a t8 lead screw. printer is homebrew, corexy, duet board, revo roto printhead.