I’m getting some of these earlier videos in my feed, always great reminders. I do special purpose tubes with a spiral hole down the middle the OD has to coaxial to the hole as does the threaded feature on one or bot ends. In addition to that the faces on the ends must be perpendicular to the hole. They are long so I either use a thin shop made chuck on the outboard end of the spindle to help support and align the job. A precision ground rod with various bushings are used to “reach “ down the hole from both ends create additional points to indicate. I might take a jump into this and make a video of the process. This set up can take some time as toy showed where you adjust in one point it affects another.