Bad surface

[julian.riechert]

I have a problem with the surface quality in a very specific place on a certain part. It looks like a classic problem with the resonances. But no matter what I do, it doesn’t get better.

What I have already tried:

Re-tensioned the belt according to Bambu Wiki (loosen screws, move head, tighten screws)

Print speed: Most tests at 60mm/s. It can’t be the speed, because I did the VFA test from Orca in the range 40-200mm/s with almost perfect results (see picture)

Flow rate adjusted 3% downwards. No change.

I printed with Bambu PETG-HF with the original settings for this filament.

Addendum: While I am writing this post, I just see that the problem SEEMS to have been resolved after I changed 2 parameters: wall generator from classic to Arachne and print order outside/inside instead of inside/outside. I could of course find out for myself through further testing whether the key was one or the other parameter. I would guess the latter. But that still wouldn’t explain why only at this exact point with a geometry that is identical to the rest (symmetrical, round contour).

What do the experts think about this?

[Lenyo]

Probably need a bit more info for a pro to perfectly diagnose (all slicer settings, what was the number of walls, infill type and percent, overlap, etc). Disclaimer, i’m far from a pro.

But you did the right thing, I think both of those can lead to a better outcome and also think you are right, the outer wall first is hiding the infill better, it looks something like infill (gyroid?) pattern interference versus a VFA style pattern in the first image.

The second image looks like VFA or perhaps not the highest quality model exported.