All that talk about Beech below - Question

Re: All that talk about Beech below - Question

Dean J in MN

>I think this article addresses your question quite well.

http://planemaker.com/articles_beech.html

Re: All that talk about Beech below - Question

Warren in Lancaster, Pa

>When people talk about a wood being unstable they could be talking about two slightly different issues. One is the shrinkage and distortion which occurs during drying and the other is the seasonal expansion of dried wood due to humidity changes. I think the reputation you talk about is due to the fact that beech has pretty good shrinkage when drying and is prone to twist and other distortions especially around defects or reaction wood. These problems are pronounced in 4/4 stock, but much less in thicker stuff.

Once dry beech is fairly stable in the radial direction and somewhat above average for seasonal change in the tangential direction. Another property which is not well documented is that woods tend to become more stable after going through numerous humidity cycles. My 100 year old trying plane does not change in a measurable way from winter to summer. I once purchased a molding plane that was hardly ever used because it was warped in such a way that it did not work well. I trued things up and it has been stable for ten years.

clarification of stability and relevance to planes

Bill Tindall, E.TN

>First, the shrinkage upon drying and the change in size in response to humidity after drying are essentially the same. The stability tables are indeed calculated from shrinkage during initial drying. Both these properties are determined by the change in size of the piece as a function of moisture content of the lumber. Two factors affect both these stability properties. First, is how much does the lumber change in size in response to change in moisture content. Second, how different is the radial vs tangential shrinkage. This second factor is most important in determining how much a piece can/does warp and twist upon initial drying. The first factor in more important in determining how much the piece moves around after drying.

Additional relevant information. For good reason you won't see furniture built from American beech. European beech is a different species. It is usually steamed which will make it more stable. I have read that plane makers often boiled the wood before drying. This treatment would also promote stability by removing lignin. Planes are made with quarter sawed stock and it is orientated to promote a stable plane body.

Weed Tree

Warren in Lancaster, Pa

>Today I used a beech trying plane that was made around 1900 and I have used since 1978. I also used a beech marking gauge that my grandfather bought for my father in 1930. Tonight at supper I sat in a chair that has beech legs and beech back posts and was made around 1810. At least six generations of my family have sat in the chair- I don't know the history before 1885. Pretty good for a weed tree.

try selling some logs or lumber

Bill Tindall, E.TN

>and my description of beech as a weed tree will become more clear. Last I checked the log yard was paying $200/ 1000bdft for delivered logs except they weren't sawing ties for a while so they were not taking beech at all.

Beech has a huge dense canopy so nothing grows under them. They occupy space in the forest and provide no $ value. They do, however, provide homes for hollow tree dwellers, possums and the like, as well as nuts in the occasional years they bear.

Re: clarification of stability and relevance to pl

Wiley Horne

>Bill (and others as well),

I'm interested in your thoughts on the following:

I think Warren's thesis may hold water (so to speak)--that as wood dries and shrinks, it exhibits slower moisture exchange. My unscientific observations won't prove it, because our climate swings are pretty mild here through most of the year.

But it is not a stretch for me to imagine that the water transfer rate constants will change as wood dries. Maybe as wood dries and shrinks, the channel capacity gets smaller.

Wiley

Re: try selling some logs or lumber

Larry Williams

>We've paid some premium prices for custom sawn beech. One can buy cocobolo about half what we paid for beech last spring. I don't doubt the commercial furniture industry doesn't have much call for beech. They seem to prefer MDF and plastic. The timber industry avoids beech because of it's susceptibility to fungal growth and the difficulty in drying the wood.

In forestry, the definition of "unstable" relates to the ratio of tangential to radial shrinkage from green to dry. It has little to do with ability to stay in place. A good example of this is persimmon which is, by the forestry definition, more unstable than beech. One of the main commercial uses of persimmon is for pool cues. I doubt there's a market for warped pool cues.

It's called hysteresis

Larry Williams

>I don't know of any studies into its effect, but it is a real phenomenon.

Re: All that talk about Beech below - Question

ThomD

>I can't agree that beech planes are quarter sawn, I rive mine, but as far as how the grain orientation is in finished planes, the few antiques I have have the grain parallel to the bench surface in use, which makes some radial and others tangential depending on the dimensions of the block. At the least one would hope the riven or sawn stock would be of perfect quality.

There do appear to be some adequate/wonderful characteristics to beech in American planes. On the other hand the great depth of scientific argument may at some time start to sound like rationalization along the lines of why Howard Hughes built the Spruce Goose out of birch... The war department wouldn't give him the metal. I'm not saying metal would be preferable here, far from it. But beech seems at least a partial economic compromise.

It has been studied

Bill Tindall, E.TN

>I had a paper on the topic by Wengert when he was at VA Tech. I have torn the house down looking for that paper and can't locate it.

Re: clarification of stability and relevance to pl *LINK*

John H. in Baltimore

>The link provided below is to a Forest Products Laboratory publication regarding wood properties.

"Sorption hysteresis" is discussed on page 3-7. Through this property, the equilibrium moisture content at a particular relative humidity differs -- depending on whether the wood is absorbing or "desorbing" moisture.

Regards,

John


http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch03.pdf