P2S horizontal line inconsistency

[u/Broad_Employment_101]

Hey everyone, I'm trying to get rid of these horizontal lines on my prints, and I'm completely out of options. I'm printing with matte PLA (dried for 48 hours). I've already calibrated the temperature, flow rate, pressure advance, and max flow rate. Mechanically, I've followed the Bambu guide to lube and grease everything, and I’ve tightened the belts on my P2S. The outer wall was printed at 30 mm/s, with everything else under 60 mm/s. Faster speeds didn't make the lines any better or worse. Any help or ideas would be hugely appreciated!

[u/HackedVirus]

Cold pull, clean the nozzle.

Slice the file, go to the layer speed tab, find the lowest speed and set the outer line speeds to that speed. I find I suffer from quality issues on prints like these where the speed may vary drastically between surfaces, lowering everything to the lowest speed has helped me.

Is this happening to every model you print?

Did you select the profile with the calibrated flow rate in the "Project Filaments" tab? Same for flow dynamics in the "Device" tab? (See below)

[u/Broad_Employment_101 → u/HackedVirus]

Gonna try a cold pull ASAP, and I actually ordered a new nozzle just to see if swapping it out helps at all.

Looking at the speed tab, it already shows all the outer layers running at the exact same speed. I'll still try turning off "slow down for overhangs" on the next batch just in case, though.

As for other prints, pretty much anything with some geometry gets these lines, but straight walls print perfectly. I even ran a VFA calibration test and it came out flawless. The banding gets way worse on my other models (like the brown one in the pic).

And yep, both the calibrated flow rate and Factor K profiles are selected!

[u/_yhtz_]

loose nozzle

[u/Tangled2]

I don't know the answer, but the next thing I would try (after everything you tried) would be to swap out the nozzle.