A treble in trouble

[Delwin D Fandrich]

A440A@aol.com wrote:

> Greetings all,  can we talk about this?
>
> Del writes:
> >And to a certain extent strings can be
> >"pre-stretched" a bit by rolling them or pressing them--temporarily
> stretching
> >them well above their normal pitch--as is the
> >practice of some factories and rebuilders. These practices can all >help to
> improve initial tuning stability.
>
>      I agree, however, these practises can overstretch a lot of strings.
> There is a limit of tension a  wire will accept without deformation, when
> surpassed, you usually have a tonally deficient string, ( at least I do,
> after maybe, a chipping "accident".).  Stretching strings "well above" their
> normal pitch by rolling is asking for excessive stretching.  I think
> factories suffer from some of this, judging by the amount of false strings in
> some domestic instruments.

Ed,I agree with you! We don't "pre-stretch" strings by either rolling them or depressing them in any way. I mentioned the
practice only because if I didn't someone out there would have been sure to inform me that it was possible to do so and would
now be extolling the virtues of the practice. We generally don't even pitch raise new strings much more than a quarter of a
step sharp.


> .....If you combine the details of settling all the string
> bends when you have it this sharp,  the piano can be amazingly stable in
> weeks.

We do all of the details. We squeeze at the hitch pins, seat at the bridges, seat at the V-bar/agraffes, seat at the
counterbearing bars (both front and back), pull the coils tight, etc. And, yes, the piano can be fairly stable with itself in
a few weeks. But nothing will prevent the strings from stretching over time once they are brought to pitch.

Perhaps I should also have mentioned that most of the pianos we do get new boards, so that is also settling quite a bit
through the first year or two. Yes, I know they continue to change beyond that but the majority of the wood's compression set
has occurred by then.


> .....I have come to believe that the deformation required of
> the wire at every bend along its length is by far the most important factor
> in determining the stability of the wire's tension.  How much stretch is
> there in the straight portion of the string?

A fair amount. There's a formula in my files somewhere but it would be a pain in the neck to dig out -- it's not something I
carry around in my head. There's a lot of stuff still in boxes. Check with one of Al Sandersons class outlines. It's a
function of string diameter, tension and length. I also think there was a Journal article on the subject a few months back.
If you can't find it, I'll try to track it down unless someone else comes out with it.-- ddf