Ben, I've been a member at Lumberjocks for 11 days now, and finally decided to jump in instead of lurk. I hate to say it, but you don't need a lot of elbow grease to get your bowl sanded, and truing it up can be a piece of cake if you think about what you need to do.. I'm pretty bad at trying to relate how to do something, but I'm going to try.
Getting it trued up is nothing short of making a thick jamb chuck the size of the inside diameter of your bowl. I would use 2 pieces of 3/4" MDF to get the thickness. If you have a chuck, attach a tenon to this jamb chuck. Turn it to fit the bottom contour of the bowl. If your bowl is deep, add another thickness of MDF. Use that non skid sheet that is used in drawers in the bottom between the MDF and bowl.
Turn something that will go onto your live center that will not leave marks on the bowl bottom.It doesn't need to be bigger than 1"od. Lock the tailstock and adjust it until you think you can re-turn the bowl without it coming off the lathe. Sand until you think you're done, remove it from the lathe, and sand the small spot that was touching the bowl bottom.
If you want to sand the inside, do this first. Attach a glue block on the bottom and turn a tenon after the glue sets. . Mount it in your chuck, sand, turn or whatever you choose to do, and then go about the steps above for the outside. You don't need to make anything for your live center because you'll have the tenon and dimple from the live center to center and tension your bowl. Turn until you have the nub that most people turn to, then remove it from the lathe, cut off the nub, and sand the small spot on the bottom to completion.
I've invented several tools that makes remounting a completely finished form a no brainer. In a couple weeks I'll post pictures if you are interested. ............ Jerry (in Tucson)
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