put a "finished" bowl through a drum sander?

[Prashun Patel]

How close to flat are you? Can you post a picture?
Also, is the base a flat plane, or is there a recess?

I always turn the foot slightly concave to insure the only contact points are along the rim. If you do it this way, then HAND sanding the foot level becomes a breeze - assuming you are within shooting range off the lathe and only doing micro-adjustments.

Re-mounting a bowl without a center reference mark isn't always fun (for me!) and often leads to bigger probs than just tweaking it by hand.

Even better than hand sanding is using a rasp. Even better than that is using a block plane, router plane (for me).

[John K Jordan]

...
Re-mounting a bowl without a center reference mark isn't always fun (for me!) and often leads to bigger probs than just tweaking it by hand.
...

That's the truth!

Although my remounting got a lot easier when I carried a dial indicator from my little machine shop to the wood lathe:

Dial_indicator_IMG_20141122.jpg three_corners_glass_IMG_7157.jpg

I usually adjust by measuring the rim but in this case I only needed to turn the transition where I glued together the 3-cornered top and base. I usually check in several places.

JKJ

[Dan Gaylin]

Thanks all for the additional responses, you guys are great. John, I aspire to have my bottom look like your bottom :-). And yes Brian I appreciated the humor. I usually make the bottom of my bowls slightly concave, although not a work of art like John's. Because of all the effort I went to to get this bottom narrow, and my problems with the live center, I ended up sanding the last bit of the tenon off by hand, again because I was worried about a catch. I should look into the various special live centers that John suggested. The bowl is pretty close to flat, it just rocks a tiny bit, so I could just leave it. Most people wouldn't notice it. It sucks to be a perfectionist with intermediate (at best) skills. It didn't occur to me to try to hand sand it concave. I just went for flat.

[Mike Nathal]

Free hand sanding using a 2 inch sanding mandrel in a drill press (or your lathe) also works well. I have a flat glass plate that I use to check that the piece doesn't rock. Also, even with a concave base, sometimes I find that a piece that I thought was complete, several months later it is rocking again. (This is with my hollow forms with 1~2 inch diameter bases.) In this case I place some 320 grit sandpaper on the glass plate, and hold the vase firmly on the paper and slowly rotate it.

[John K Jordan]

Good point.

Someone gave me a roll of 29" wide 220grit and later somewhere I stumbled on a 12" wide roll of 240 grit Klingspor gold sandpaper (probably in the discount bin in the Klingspor store)! These are excellent for dealing with the slight warping you mentioned, common to both rims and base due to change in environment (shop vs house, etc.) or piece not completely dry when finish turned.

[Dan Gaylin]

Mike — sanding mandrel in the drill press. I have actually done this before and it worked great. Totally forgot about it!! Thanks for the suggestion. I have float glass plates for plane blade sharpening so that’s a good idea too.

-dan

[John C Bush]

Use your left over belts from your drum sander. 3M #77 adhesive spray on plywood scrap, stick on the paper, clamp it to the bench and start smoothing. Works for the rim as well. I used one to finish sand a bunch of French pastry rollers on the lathe.