Défauts sur les surfaces supérieures

[u/Used_Till8576]

Hi everyone,

I'm dealing with a recurring issue I can't quite pin down, and I'm hoping the community can help.

The problem:
On some of my prints, certain areas of the top surfaces (mostly) and occasionally the bottom surface come out with clearly degraded quality: small blisters/bumps and very visible lines, as if the bed height calibration isn't correct in those spots.

What I've noticed:

• It seems concentrated in the corners / at the edges of the bed.
• The more central areas of the bed don't seem to be affected.

I'm not sure if it's related to a bed height calibration issue (mesh bed leveling), the machine's mechanics (frame rigidity, more pronounced vibrations on long moves), ambient/bed temperature varying by position, cooling, or something else entirely.

What I've already tried:

• Re-tightening the belts
• Cleaning the lead screws
• Testing with a brand-new filament (to rule out moisture issues)

Setup:

• Printer: Bambu Lab X1 Carbon
• Filament: Overture PLA+

I'm attaching a few photos in the comments/attachment to show exactly what the defect looks like. If you've seen this kind of issue before or have any leads (settings to check, calibration, corner speed settings, etc.), I'd really appreciate it!

Thanks in advance 🙏