RA2 - ring setup (external burn) - does not stay in a consistence distance from the laser during the rotation. The ring moves around the axis (less than 1mm - not measured) which causes the engraving and scoring to be inconsistent result due to the distance varying from Laser to the ring (slightly).

I have read the instructions.  Ih ave taken time to eyeball the alignment and also ensure that the chuck is not over tight.

Is there a method to ensure that stabilises the ring location?

Ideally you would have either a shorter stud posts and / or have the tail module to stablise the stud posts.  Also a redisgn of the stud posts with a flange at the screw thread would also insist in ensuring the stud posts stay parallel to the rotation axis.