tapping strings

[Jon Page]

At 03:11 PM 4/5/2002 -0500, you wrote:
>Another fly in the ointment......when wood expands in high humidity, don't
>holes get bigger?

Holes get smaller in high humidity. Wood expands, not holes (no wood),
so the wood expands into the hole or crushes around a tuning pin or bridge pin.

>Clicking noises in teflon bushings are usually heard in the dead of summer.

That would account for the yoke shrinking and the bushing becoming loose.
the Teflon bushings get looser in damp weather. Joe Biscelli (sp) demonstrated
this at a seminar by placing a teflon s/f in a glass of water for 20 
minutes. It was
excessively loose.

>Still, if there's enough of a rise in the board/bridge,
>the increased looseness would likely be countered, right? (Maybe this
>explains Ron N.'s instistence that pins do not climb out of their holes?) By
>the time the board/bridge start sinking (and shrinking), the humidity level
>has dropped and the hole, presumedly, would have shrunk, becoming tighter.
>
>With this in mind, isn't it more likely that exaggeratedly low humidity
>levels are the cause of loose bridge pins? That seems like an obvious thing,
>but I'd think the extra shrinkage would be the cause of crushed wood in the
>bridgepin holes -- the result of *low* humidity instead of the typical
>result of high humidity.

When the humidity rises, the bridge expands and pushes the string up the 
bridge. the
wood also develops a compression set around the bridge pins.

When the humidity lowers, the bridge shrinks. The area which was under the 
strain of the
wire is dented and shrinks below the level of the center of the bridge 
which did not become
so compressed. The pin holes shrink and the pins becomes loose, this 
compounds the
effect which produces false beats: loose pin hole, compressed (broadened) 
surface edge face.
Room to move.

Have you noticed how when you tighten the flange screws in the winter then 
check them again the following winter
they are loose?  The wood swelled during the summer humidity and crushed 
against the screw head (compression set).
Once the wood dries back, the flange is loose, not from the screw loosening 
but the wood compressed.

Jon Page