Considering the premise of using CD/DVD drive mechanics for milling, I thought #CDCNC did pretty well at making round circles. Especially compared with common results for glue-and-go CD/DVD-derived CNC projects.
First try with this less constrained project, using a test part that I (mis)cut a lot of working on the prior project, yielded much rounder roundness:
The round part of each is ~11 mm diameter.
Note encrustation around inside of outer ring. Complained about that in prior log. I scrubbed more off with a wood toothpick.
(Apparently monochrome-on-black figures that are mostly edges compress very well. That 1900x1900 image compressed to 1 MB. I could resize it, but considering small data size, I'll post it big and tell myself that everyone's browsers will do something sensible with the large dimensional size. Lemme know if I should have told myself something different.)