I’m having a very similar issue to what you were having, on three different X1C’s, only when printing cylinders greater than ~50mm diameter. In this case the issue seems to stem from how Bambu Studio generates the G-code on models imported from STP files instead of STL’s.
I discovered the issue while printing with PLA with 0.4mm nozzles, 0.2mm layer height, standard speed. Using Bambu Studio version 1.9.1.66 and firmware version 01.08.00.00 (currently the latest version).
I’ve done dozens of nearly perfect prints with the same material/settings in the last few weeks (importing from STP), but over the last couple of days I’ve been trying to print some cylindrical parts with roughly 80mm OD and 50mm to 90mm ID, and the walls look TERRIBLE - with a very severe, inconsistent ripple pattern in the walls that looks very much like the photos at the top of this thread. So far no outright spaghetti failures, but the worst examples have many blobs and stringing.
Prints still come out nearly perfect on smaller cylinders (~40mm diameter or less) and other shapes.
Definitely not wet filament; I maintain three extra desiccant containers in my AMS’s and humidity monitors inside the AMS’s all reading 10% (the lowest they will read.)
Occasionally, the OD or ID will come out smooth, but so far never both. In a couple of cases, the bottom few millimeters of the OD was smooth but everything above it had the severe ripple artifacts.
While the issue is happening, as the head travels in a circle the printer vibrates more loudly than normal, with a rapid “stuttering” sound from the X/Y chassis, as if the stepper motors are briefly being put under high load by attempting short, very rapid deviations from a smooth circle. This seems to indicate that the issue is related to head X/Y motion rather than filament flow.
I first ran into the issue while trying out the new scarf seam feature, but it happens with and without scarf seams.
I tried the “Fix Model” command but that didn’t help.
Increasing the resolution setting (Quality > Precision>Resolution) from the default of 0.012mm to 0.02mm and 0.03mm does not fix the issue (As suggested by DzzD in post Banding / Ringing type artifacts? - #168 by Jrock).
In all cases, the previews of the STP-imported models in Bambu Studio look fine, with smooth walls and no faceting.
Importing the same models as STL files fixes the issue, but of course the parts have the typical STL faceting. Eliminating that faceting is the reason I preferred (until now) importing models as STP files in the first place.
Turning off Arc fitting produces similar wall-ripple artifacts, but with much smaller magnitude and frequency. The appearance is much better, but still quite a bit uglier than faceted .STL-imported files.
