Quote Originally Posted by JAZZCNC View Post
You have to remember these are rotary axis, not lathe's so the runout will hardly be noticeable for the majority of work and if you require higher precision then you either use 4 jaw chuck or use soft jaws and bore them as MC suggested. The pulley runout is of no concern whatsoever in this application.
This is a 4-jaw chuck... which is why I expected higher precision, but sure, I understand that for most things this error will not make a difference.