warning: intense discussion of tension

[Ron Nossaman]

> I have read posts quoting the amount of tension on a grand plate, how 
> much tension is added with a pitch raise, references to low tension 
> scales, high tension scales...etc.
>  
> How is this measured?   And where are the measuring points?  I mean, are 
> we talking from one end of the plate down at the heel of the piano all 
> the way to the part that abuts the stretcher?  Or from agraffe to hitch 
> pin?  Tuning pin to hitch pin?
>  
> How about string tension?  Does this refer solely to the speaking length 
> of the string, or from tuning pin to hitch pin? 
> 
> All these numbers get thrown around but in the end I have no 
> understanding of exactly what is measured, and how.
>  
> Does anybody know?
> 
> Just curious,
>  
> Tom Sivak
> Chicago

Hi Tom,
First off, tension isn't a linear measurement. A string at "X" 
tension can be of nearly any length that's likely to fit into 
a piano. Tension is nominally the same through the full length 
of the string, from hitch to tuning pin, and at any 
arbitrarily defined segment  between the two points. The total 
tension, and tension changes resulting from a pitch change, as 
discussed on list, aren't directly measured, but rather 
calculated from the string scale and starting pitch. It's a 
means of getting a feel for something not easily measured 
directly.
Ron N