humidity, teflon, hell, jon, whateve:(Was Tapping Strings)

[David Skolnik]

Ed  and Jon -
I'm not sure how relevant this particular characteristic is when it comes 
to dealing with the causes of loose bridge pin, however, as it specifically 
relates to teflon, the mistake here is in Jon's statement  "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." This 
is not true. In humidity, the wood expands across the grain OUTWARD, away 
from itself, relieving the pressure on the bushing.  In dry weather 
(Winter), the opposite occurs.  Ed's example of the hole drilled in high 
humidity being oblong at Christmas would not prove out, I suspect, in that 
the shape would be created by the difference in dimensional shrinkage of 
the end grain verses across the grain.  The end grain change would be less, 
creating the out-of-round, however, the cross-grain shrinkage would exert 
enough pressure on the teflon bushing to cause the pinning to be 
excessively tight, requiring easing.  The stuff that was loose in winter 
would probably be caused by previous deformation of the teflon, mis-easing, 
or Satan.

The most important contribution I can make to this discussion is 
BISCEGLIE.  If you spell it wrong, he doesn't get his check.

Regards-

David Skolnik






At 09:39 PM 04/05/2002 -0500, you Ed Foote wrote:
>  jon  writes:
>
> >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.
>
>   I'm with you there..
> >>Clicking noises in teflon bushings are usually heard in the dead of summer.
>
>Starting to lose me........
> >
> >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.
>
>   Ah,  lost.  The changes the teflon shanks see are a lot more subtle than
>the glass of water.  However, if you were to put that shank in the water
>before you drill that hole, you would find that teflon bushing fit snug and
>evenly in damp weather, but was oblong in the dry season and would do its
>clicking at Christmas.  The wood hole is only round in one humdity, and
>distorts the teflon when opposite conditions are there.  (least, it seems
>that way to me).  Some of those pianos had problems in summer and some were
>loose in winter.  It did seem to vary by instrument.
>      When I soaked the ends of shanks in penetrating epoxy, and then later
>installed the teflon, the bushings never changed, (8 years on a concert stage
>at Vanderbilt).   Joe Bsicelli saw them and told me that it worked but since
>it changed the color of the wood, they would never do this at the factory.
>    It won't be long before this is an entirely moot point, the teflon 
> actions
>are disappearing quite nicely.
>Regards,
>Ed Foote