Seasonal pitch change:

[Cy Shuster]

----- Original Message ----- 
From: "Ron Nossaman" <rnossaman at cox.net>
To: "Pianotech List" <pianotech at ptg.org>
Sent: Saturday, March 10, 2007 9:01 AM
Subject: Re: Seasonal pitch change:


>
>
>> Yes, why are the strut-adjacent strings less stable?
>
> They aren't on both sides, only on one side.
>
>
>>Sure, the bridge has no downforce for a bit; does that mean the soundboard 
>>(and/or bridge) bulges up there when the whole board swells?
>>  --Cy--
>
> Why would there be no down force on the bridge "for a bit"? And how, if 
> soundboard rise and fall will have so little effect on tuning, would that 
> explain it anyway? And what would conceivably make soundboards bulge at 
> plate struts?
> Ron N

I'm thinking of designs where there are no strings running under the struts, 
and thus there's a horizontal gap of an inch or two between the bridge pins 
for strings on either side of the strut.  No strings, no downforce in that 
small area; bulging?  If the bridge itself is plenty strong, is it just the 
scaling problem caused by the interruption of the strut that creates the 
instability?  (As you mentioned in an earlier post)

--Cy--

P.S.  Wish I could come up to Salt Lake next month.