string pressure on board

[Delwin D Fandrich]

----- Original Message -----
From: Ron Nossaman <RNossaman@KSCABLE.com>
To: <pianotech@ptg.org>
Sent: June 27, 2000 12:05 PM
Subject: Re: string pressure on board


> Arbitrarily using a 6' 3" grand scale that was on the short file list in
> Excel, at A - 440 I have an overall tension of 37,566lbs of tension, and
> 470lbs of downbearing. At A - 435, total tension is 36,717, and
downbearing
> is 460 lbs. In actual practice, which my scaling spreadsheet and I aren't
> smart enough to figure automatically, the board would rise some with the
> tension drop and the bearing would be somewhere between 460 and 470. Not
> much change compared to the tension. That bearing is for a new board with
> bearing ranging from about 0.4° in the bass and low tenor, up to about
1.5°
> in the high treble. In older soundboards with less bearing, sometimes a
lot
> less, it won't be nearly that high, and bearing load changes with pitch
> changes will be very small.
>
> Ron N

-----------------------------------------

I knew Ron would have the numbers!  Where does all of this mythology come
from?  This stuff is not rocket science.  It wasn't back at the turn of the
last century either.  Still, these ideas take hold and spread and don't give
up easily to logic and common sense.  Oh, well...

-- ddf