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Mark Kelly
11-15-2004, 12:33 PM
I have three questions that I couldn't find via search:

1) I have a green bowl blank of 5 1/2" diameter and 2 3/4" height to turn. What minimum thickness should I turn this so that when it dries it doesn't crack?

2) How do I dry it after turning the initial blank? I don't need to dry them quickly like mentioned in the other post about using alcohol.

3) I have a piece of 3" square by 12" long piece of 'almost' dry red oak. It was cut in Febuary of this year and has been air dried all summer long. I live in a relatively low humidity part of the country (except for the past few days!) I forgot I had this piece when I asked about turning a mallet a few weeks ago. I plan on turning it into a mallet, but am not sure if it is better to wait until it is completely dry to turn it. Any thoughts on this?

Andy London
11-15-2004, 2:15 PM
Mark, It would help if we knew what kind of wood it is, generally however I turn howls 1/2 to 1", depending on the size and the wood in question. Drying where I live after it is sealed takes about 6 months.

Can't comment on your oak as I am not sure how long it takes wood to dry where you are, if it were here, then yes I would turn it now, but I also have a moisture meter to check it, I find Oak very easy and quick to dry.

Andy

Mark Kelly
11-15-2004, 2:17 PM
I believe it is Chinese Elm. How do you go about sealing it?

Barbara Gill
11-15-2004, 2:51 PM
1) I have a green bowl blank of 5 1/2" diameter and 2 3/4" height to turn. What minimum thickness should I turn this so that when it dries it doesn't crack?
I use a standard rule of thumb of 1"/10" diameter but usually don't go <3/4". Without going back and looking I believe there was a recommendation for the alcohol soak. There are no guarantees that the bowl will not crack whatever you do.

2) How do I dry it after turning the initial blank? I don't need to dry them quickly like mentioned in the other post about using alcohol.
I usually put AnchorSeal on the end grain and put in paper bag. It stays in the bag for about 1 year. My shop is not heated; I rarely have a bowl crack.

3) I have a piece of 3" square by 12" long piece of 'almost' dry red oak. It was cut in Febuary of this year and has been air dried all summer long. I live in a relatively low humidity part of the country (except for the past few days!) I forgot I had this piece when I asked about turning a mallet a few weeks ago. I plan on turning it into a mallet, but am not sure if it is better to wait until it is completely dry to turn it. Any thoughts on this?[/QUOTE]

I never have turned oak so can't comment

Steve Inniss
11-15-2004, 5:50 PM
Mark,

1. as Barbara said "There are no guarantees that the bowl will not crack whatever you do."

2. I rough turn to 3/4" to 1" depending on size/wood/grain (3/4" in this case), then I leave them for 6 months+ (unless I do LDD, or whatever) just as they are. I have found that the ones that are going to crack are pretty much going to do it anyway -stresses as well as moisture loss. Getting the rough turning consistent thickness seems to be key as well - overly thick bottoms are a killer. I do however, use anchor seal on the end grain if I am not able to rough turn right away.

3. Oak, especially after that amount of drying is quite cooperative (non-crackwise) - but hey load it up with BLO and turps or whatever as soon as you've turned it.

-Steve

George Tokarev
11-15-2004, 6:41 PM
If it is elm, it's bulletproof. Short of throwing it into direct sunlight at noon, it's almost impossible to screw it up. With interlocked grain, it's a bit unpredictable as far as direction of motion, so 3/4 would be good even on such a small piece, where normally you'd go a half inch. Gives you a chance to recover circularity after a dimple forms. Put it under a newspaper or paper bag tent for a week, then free air for a month or so.

If it's oak, different matter. You'll want to protect it after you're done to get best results. Spin as much unbound water as possible out of it, then let it breathe in the shade until the surface is no longer wet to the touch. You may now control the rate of moisture loss by a number of methods. Arizona is probably a bit dry to use my method, which is put it out of sight for a month.

First, the paper bag, which is an excellent way to do things, because your moisture is taken up by the bag (it's wood, remember) and sent off at a slower rate to the atmosphere. If the bag gets soggy after the first day or so, change it for fresh, or risk mildew. After a couple of weeks, if the piece isn't cool to your kiss, leave it in open air, no direct sunlight.

Second, the occlusive covering, which involves a wax emulsion coating such as Anchorseal, or paste waxing the end grain. Though I'll probably draw flak from proponents, there's no reason to coat the entire piece. Nobody ever split a bowl from the inside that I know of. Leave out of direct sunlight for a couple months before final turning.


Third is a lot like the first, just a larger container like a box. Add shavings to keep the rate of loss even slower. Some people use a variant with a plastic bag, but that would be for extreme dryness. I've never gone beyond the box and shavings method, and the Sacramento valley can be pretty dry. This one is usually a one-shot, with the box and shavings allowed, out of direct sunlight, to mellow down through a half - open lid. The bag requires a change shavings two or three times to escape severe fungus. Change for shavings already dry, week intervals, then the kiss test.

There are a number of other options and magic elixers, but since none I know of has any basis in wood technology, I won't mention them.

Oh, to tell the difference, oak has a sort of sharp tannic acid odor. Elm smells like an outhouse.