I printed my sample ring and box again, including the 90mm version and rotated the box 45*. The first 40mm version box had the “Ringing” artifacts but very faint and could not catch it on film. When I rotated to 45* on the X/Y then they became obvious - more so on the back side (rear of printer) that front.
I think that there is a hitch in the X/Y combined movements that is causing this.
Has ANYONE tried the .3mf files I posted on Thingiverse yet? Waiting for more results.
If we are doubting the export file I posted, then use your own CAD program or starting file of your choice, make the 90mm dia x 40mm cylinder with 3mm wall, and a 90x90x40mm box with 3mm wall, then slice using the same .20mm standard preset with 5% cubic infil
Same simple design and see of you are getting better results.