1% crunch

[Brent.Fischer@asu.edu]

>The discussion of spruce's ability to compress 1% without damage is
>interesting, but is at most only half the story.  Does anyone know how far
>healthy spruce can stretch without failing?
>
>Bob Hohf
>Wisconsin

Dear Bob,

    If you mean tension parallel to the grain, then according to Hoadley
wood is stonger than steel on a weight-for-weight basis when tension
is parallel to the grain.  He also says the tests are hard to conduct
and are of a limited use.

    Stretching along the grain occurs when the treble bridge is glued
to the soundboard and forces and end-to-end deflection.  I would hate
to *hear* the point of failure of that stretch which could really
ruin a soundboard and your day. This stretch under crowned conditions is
different than what the book talks about in a simple tug-of-war effect.
There seems to be a definate amount a soundboard will allow to be stretched
when gluing on the bridges.  The dynamics of all the forces in a
soundboard assembly under pressure seem gigantic. Tension, compression,
stretch, you name it. Understanding the strengths of wood and differences
in comparison to seasoning times would an interesting experiment.

Did  you hear on NPR about a venture to raise thousands of logs
from the bottom of (I think) Lake Michigan?  Apparently left over
from the logging days there are all these prime oak, sugar maple
and other species lying on the bottom in great shape. The owner
plans to mill it and sell it to woodworkers and the like.  Too bad
there problably won't be much spruce. Brent


Brent.Fischer@ASU.EDU
Arizona State University/Tempe