Tension Increase

[Ron Nossaman]

>If one raises pitch 1/2 tone to A440, how much tension is added to the 
>frame, either in percentage or pounds?
>
>I successfully carried this out yesterday on a Dominion (circa 1910) which 
>showed signs of structural weakness with the treble pin block having pulled 
>slightly forward.
>
>Just wondered how much extra stress I had caused. Tuning is scheduled in 
>four weeks.
>
>John Lillico, RPT,
>Oakville, ON


Hi John,
Here are some figures from the original scale of a grand I rescaled. 
Total Tension:
@A=440=37555lb  at pitch
@A=428=35535lb  1/2 <> semitone down
@A=415=33409lb  1 semitone down
The figures on your piano would be different, of course, but this should
give you some place to start. 

Scary, ain't it? Now go back and fix that pinblock separation. 8^)

Ron N