I have printed yesterday a threaded rod with a diameter of 30 mm and today some parts with larger holes (> 20mm). I noticed that the threaded rod is not quite round and also the holes are not really round.
Habr you also had this before?
I have drawn the parts with Fusion 360 and sliced with Luban.
I had same issue. Replaced one of the linear motors, and everything was round again. I think I had too much backlash in the rail, was getting worn out.