verrry interesting!! :-)

[Delwin D Fandrich]

----- Original Message -----
From: "Farrell" <mfarrel2@tampabay.rr.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: March 06, 2003 3:54 AM
Subject: Re: verrry interesting!! :-)


> Gee Del, I guess with this one it would make a difference whether you
measured the scale lengths before or after string removal! Maybe the plate
is made of spring steel.
>
> Terry Farrell


Well, that's how we usually do it. Unless we forget.

But, no, it probably wouldn't matter either way. The question would be just
how close to breaking strength the scaling was originally. For example, if
C-66 was originally 168.5 mm long (an example taken from real life) and
strung with #15 (0.035") wire, it would have a tension of approx. 171 lbs.
(77.6 kgf). That's about 55% of its breaking strength. It would take
increasing the length to approximately 275 mm to bring the tension on this
string up to the wire's breaking strength of approximately 350 lbs. (159
kgf). Even assuming old, corroded wire having a somewhat lower breaking
strength I can't see any plate of any material flexing that much. Not even
one made of Wurlymetal.

Now, one breaking string can be explained by defective or damaged wire. But
here we have a whole bunch of them. I'm curious. And were I Jim I'd be a
little nervous about restringing the thing with the original scale until I
figured out what was going on. (Well, no, it's not the stringing that would
worry me, it's the chipping the thing to pitch that would worry me.) Hence,
my question.

Del