Odd Artifacts on first few layers of ABS vase mode print

[Jdo300]

Hello All,

I've been working on optimizing an ABS profile in Cura 4.8.0 for printing a small test part (a miniature studded vase in this case), but I am running into issues with the outside surface quality of the first few layers.

The part is printed in vase mode (spiralize outer contour) with the following basic settings:

• Printer: Airwolf3D AXIOM Dual Direct Drive
• Nozzle Size: 0.5 mm
• Layer Height: 0.25 mm
• Line Width: 0.5 mm
• Top/Bottom Thickness: 1.2 mm
• Print Temperature: 250 C
• Bed Temperature: 130 C
• Print Speed: 80 mm/s
• Outer wall Speed: 60 mm/s
• Top/Bottom Speed: 40 mm/s

It seems that the wall layers that correspond with the Bottom thickness have the worst quality (see attached picture). Everything above it seems to print really nicely.

What I have tried so far:

1. Adding a brim (thinking the heated bed might be overheating it) - no change
2. Reducing the print temperature thinking it was just overheating - no noticeable difference
2. Slowing down the outer wall speed (first from 60 mm/s to 40, and then all the way down to 15 mm/s) - no noticeable change in quality.

It seems that the presence of the bottom layers is doing "something" but I'm stumped. Any ideas?

Thanks!
Jason O