myths

[Ron Nossaman]

Dean May wrote:
> Anecdotally, my experience is that marginal tuning pins are at their worst
> in mid winter. I am aware of someone on this list experimentally proving
> that holes shrink in dry wood. These two things seem contradictory.
> 
> Perhaps the moisture content does more for gripping the pins than does the
> actual interference fit. 
> 
> Dean

In solid wood, the holes get bigger with humidity increase, 
and smaller with humidity decrease. Pinblocks are the reverse. 
The reason is the cross ply lamination.

Dry:
(  )
I  I
(  )
I  I

Damp:
)  (
I  I
)  (
I  I

Friction coefficients do change with moisture, so that may 
well be a factor, but the primary mechanism is the restriction 
from the cross plies.
Ron N