MC gage experiment

[Overs Pianos]

>At 11:31 AM -0600 11/11/03, Ron Nossaman wrote:
>
>. . . Looking at individual planks that have twice the number of 
>annular rings per inch at one edge that they have at the other, I've 
>wondered what the difference in moisture transfer rate might be 
>between the two, if there is any difference. Have you ever tried 
>this?

Hi Ron N. and all,

A couple of observations from my recent period of sound board 
development. I haven't measured the variable drying rate between 
planks of different annular rings densities either, but I'm sure that 
it does occur, since the variation in density will inevitable cause 
the moisture loss rate to vary.

When we built test strips of CC sound board for bench loading, I 
noticed that the resultant crown radius varied according to the 
annular ring spacing of the segments that made up the sound board 
panel strip. The closer the annular rings, the smaller would be the 
crown radius. This stands to reason since the strips with closer 
annular rings, with higher strength, would be more effective in 
bending the rib into a crown.

The grain orientation in spruce also effect its drying rate. If all 
boards in a panel are accurately quarter cut, then they will tend to 
dry at a more even rate. However, should some strips be cut off the 
quarter, those strips will tend to dry more quickly since the 
medullary ray will be angling out of the face of the strip instead of 
running parallel to the face of the board. Furthermore, this problem 
also occurs with accurately-quarter-cut lumber when it is being dried 
in the stack. When a board is accurately quartered the medullary ray 
will be parallel to the wide face of the board and perpendicular to 
the edge of the board. Therefore, if the edge of a quartered board is 
not treated with a coat of something before it is stacked, there is 
more likelihood that the wood towards the edge of a board will suffer 
degrade during the drying process.

Regarding moisture meter alternatives, I think Ron N's. is the best 
I've seen to date. An image can be seen at;

http://tinyurl.com/u4ah


Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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