Help with lines on top layer

[Hebign]

Hello everyone,
Simplify3D user, I currently have a problem with my top layer.
Indeed, I can not get smooth surfaces. They are clean, well printed, but as if they had undercut.
Could someone tell me if it's already a software or hardware problem?
How to remedy this?
I'm printing with PLA Grossiste3D 1.75

[img]https://drive.google.com/file/d/1saivCi ... sp=sharing
https://drive.google.com/file/d/1Wrvfq5 ... sp=sharing
https://drive.google.com/file/d/1onKBvJ ... sp=sharing
https://drive.google.com/file/d/1qO1c52 ... sp=sharing
https://drive.google.com/file/d/1T18dUU ... sp=sharing
https://drive.google.com/file/d/1P4axxR ... sp=sharing
https://drive.google.com/file/d/1ApGMDy ... sp=sharing[/img]

[gearsawe]

Outline over lap may be a little high try 20%

[Geek2Nurse]

Have you tried increasing your top solid layers / perimeter outlines? I've had better luck with higher numbers there, so I default to 5 now, and adjust from there.

[Hebign]

At this time, i'm calibrating all my CR-10 and flashed it with Marlin 1.1.8.
I discovered that a part of my problem became from a bad X tensioner belt i have printed. Since i replaced the original, it's better.
Either or, i'm actually testing higher perimeter and solid layers value and i try to set down my first layer height and widht because my first layer wasn't clean.
I'm trying with Top solid layers at 5 and Outline/perimeter shells at 5.
I'll come back here to tell you the result.
Thanks and best wish.

[ikaplinsky]

From photos you have attached I consider that it is not a top layer problem, it looks like Blobs.
In this case learn "Blobs and Zits" section, there are good recommendations to suppress such artefacts
https://www.simplify3d.com/support/prin ... s-and-zits