Problem with surface quality of external wall on cup and bowl shaped prints.  

Problem with surface quality of external wall on cup and bowl shaped prints.

Hi,

I've recently assembled a Prusa i3 MK3S+ and in general it is printing really well. However, I have been having a problem with the surface quality on external walls of parts that are cup or bowl shaped. I've attached a couple of photos to help explain the issue, but essentially on layers where there is solid infill on the inside of the cup (for example at the base of the cup) a small lip (or possibly an indentation) is formed on the exterior wall even if the wall is several millimetres thick (as it is in the example part I've shown here). I'm wondering if anyone has any suggestions as to what is causing this problem and how to alleviate the symptoms.

I'm printing here in Polymaker Polylite PETG (the problem persists with PLA) and I've attached the *.3mf file to this post. Increasing the infill percentage and the number of external perimeters appears to help a little, but I'd rather solve the problem properly. Please let me know if there's anything that I can add to help explain the issue more.

Thank you very much 🙂

test-bowl.3mf