I’ve said this before, don’t know if in this group or not.
It doesn’t matter how much runout a lathe spindle chuck has IF (underline IF) you use a piece of rough stock larger in diameter than the largest finished diameter on your project, and IF you turn ALL diameters on your project in the same chucking and then part it off, all turned diameters will be concentric within the accuracy of your spindle bearings. IF you need to remove the project from the chuck to turn it around to face etc, and additional turning work needs to be done that needs to be concentric, then best to use a 4-jaw independent chuck and dial the work in with a dial indicator for the additional turning work that needs to be done during the second and subsequent chuckings.
Steve Haskell
Troy, MI
Steven H