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Out of Round Bowls

Paul M. Kaplowitz

Paul M. Kaplowitz

Joined
Oct 6, 2008
Messages
395
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Location
North Charleston, SC
Doug Olsen posted a common problem of bowls going out of round as you turn them. I have had this happen on many occasions and I know the bowls are dry. I rough turn, coat with Anchorseal, weigh and dry. The bowls go out of round as you turn the inside and thin them out. What I do is completely finish the outside before I do the inside. If they go out of round and the outside is finished it doesn't affect finishing the inside.
 
Another approach, though I have to say I've never had much problem when the wood was at what I thought was equilibrium, is to turn outside, inside, trim outside then back inside. Note, however, that changes in moisture content are going to move it again.

Or you could boil to slide a bit of lignin and relieve some stress. Nuking a fresh rough in a plastic bag will relax it pretty much the same way.
 
Wood moves. Fact of life. The only time it is really important to have it perfectly round is if you are turning really thin, say 1/8 inch or less. Then, true up the outside first, then take the inside down in short stages. I prefer warped myself.

robo hippy
 
I tend to thrice turn green wood when I want to go thin. I rough it then let it sit for several months, then true it round again and let sit a week. The second turning releases some stresses and it mildly ovals pretty fast. There is far less movement after the final turning when I do this.
 
Paul, I am not going to preach as its been hammered here many times. In general air drying will not get out the bound cellular moisture. Thats why I kiln dry my roughed bowls. Couple that with limb or compression wood and with the heat of your tools screaming out that moisture I would do as you and totally do the outside before taking down the inside. Knowing its going to move.
 
KellyDunn said:
Paul, I am not going to preach as its been hammered here many times. In general air drying will not get out the bound cellular moisture. Thats why I kiln dry my roughed bowls. Couple that with limb or compression wood and with the heat of your tools screaming out that moisture I would do as you and totally do the outside before taking down the inside. Knowing its going to move.
Click to expand...

You certainly do NOT want to preach that. No matter if it's in the kiln or in the garage, it is the AIR that carries away (or carries back) moisture to the wood. The cellulose adsorbs from the air or gives back according to the percentage saturation of either. Where do you think it goes?

Bad technique to press, that's for sure. That will get you into the skate over endgrain, slice into long syndrome. Which will leave less on long than on endgrain, and show an uneven thickness in addition to heating the work. Lots of people press when sanding, doing the same thing. Not as efficient, really, as keeping contact with the grit, and letting it discard the dust continuously.

Thin stuff likes the firm backing of a steady to keep things even in thickness.
 
Paul M. Kaplowitz said:
Doug Olsen posted a common problem of bowls going out of round as you turn them. I have had this happen on many occasions and I know the bowls are dry. I rough turn, coat with Anchorseal, weigh and dry. The bowls go out of round as you turn the inside and thin them out. What I do is completely finish the outside before I do the inside. If they go out of round and the outside is finished it doesn't affect finishing the inside.
Click to expand...

I think that is as good a procedure as any and basically what I do on wood that warps. As mentioned, wood moves and you just need to be ready for it as best as you are able to do so. Even kiln dried lumber moves if it contains reaction wood.

Even if thoroughly dry, that does not automatically mean it is stable. When I used to do a lot of flat woodworking, I would occasionally get a piece of kiln dried rock maple or white oak that couldn't be ripped or jointed without warping like a banana.

The length of time that it take for a piece of wood to completely air dry can be extremely long. I was pleasantly surprised last fall when I cut a piece of mesquite that had been lying on my driveway in full sun for more than five years to find the wood a few inches down still had a high moisture content. Oh, I forgot to mention that this piece of mesquite was about 32 inches in diameter (a real prize). 😀
 
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