Higher wall count = z-banding

[SavvyPrints]

@KanneKaffe

Set the speed for external walls to a fixed lower value, for example 65mm/s.

Thanks for the suggestion! I’ve already tried that as well, unfortunately. I incrementally decreased the print speeds in multiple combinations. First I tried only adjusting the outer walls, then interior, then I adjusted both as well as overhang speeds.
I started with a modest speed drop to 200mm/s, then 150, and so on, down to 60mm/s, then 45mm/s, and in the end I actually just set all wall speeds to 10mm/s and dramatically dropped overhang speeds as well. For a majority of my troubleshooting, I’ve typically had inner and outer walls down to 40mm/s-60mm/s.

@TechnicallyReal

I have an ongoing issue on Github about something that might be related:
PLA layers squished following PETG support interface layers · Issue #2015 · bambulab/BambuStudio (github.com)

I changed my design to avoid the problem and the thread has mostly gone stale.

I think problems like this might be due to layer time differences and PLA not hardening consistently as a result. Maybe if we printed the entire model much more slowly it would look better. Maybe increasing the minimum layer time might help as well. It bothers me to think that the cooling fans aren’t enough, if this is the case. Honestly I would rather find out the problem is caused by something else and can be fixed.

The crazy thing to me is: why can everyone else, except for a few of us, print multiple walls without a problem? Everyone says they have no problems printing out of the box, multiple walls, overhangs, etc, without an issue.

I’m sorry to hear you’re dealing with this too… I mean, it’s validating for me, but sucks for you…

The most common advice I’ve read is to adjust layer times so it’s all more uniform, so what you’re saying tracks.

I’ve been dreading opening a support case; all my technical intuition and experience points to my issue as being due to a user error and not a mechanical fault issue, and I’m sure support will think the same. But I’ve tried everything…

As soon as I build my ventilated enclosure, I’m going to get back to printing+troubleshooting.

Edit: btw, TechnicallyReal, have you tried adjusting the purge value for your PETG->PLA layer/s? I thought that might be a factor for my issue but adjusting the purge value didn’t help. Then I tried printing with all PLA and no PETG for support interfacing, just to eliminate PETG/PLA purge values as a factor at all, and the banding didn’t change. So I know purge values aren’t a factor for me at least.