String rollers.

[Farrell]

"I also straighten all wire before installing and never use it straight from
the coil."

How do you do that?

Terry Farrell

----- Original Message -----
From: "John Delacour" <JD@Pianomaker.co.uk>
To: <pianotech@ptg.org>
Sent: Friday, October 05, 2001 12:06 PM
Subject: Re: String rollers.


> At 22:23 05/10/01 +0000, Graeme Harvey wrote:
>
> >..but the main query I had and I didn't
> >allude to thoroughly enough was... is it possible to over-stretch wire?
> >I know that newly strung pianos settle down after preparation and a
number
> >of tunings, but it is possible to stretch the wire further still and this
> >can be demonstrated on old pianos, by simply pressing on a string and
> >hearing the pitch go down.
>
> The friction across the bridges (top and bottom) accounts for this.  If
you
> were to pull to pitch a new Steinway string, for example, with a single
> clockwise turn of the tuning lever, you would end up with too much tension
> between the wrestpin and the agraffe and too little tension between the
> hitchpin and the bridge.  This can easily be verified if you choose a
> string with tuned partials at both ends; the partial near you will sound
to
> high and the one beyond the bridge too low.  It is to even out the tension
> in the three lengths that we "set the pin", which is somewhat of a
misnomer
> because this process does more than set just the pin.  In the case of a
new
> string there is more work to do in the equalizing of the tension than in a
> piano that has simply dropped in pitch, but in either case it is necessary
> to pull up above pitch, let down to pitch and then pull up again very
> slightly to restore the tension in the nearest section and stabilize the
pin.
>
> I personally find that after a restring, with clean wire, new bearings and
> a clean bridge, practically all the setting of the tension can be done
with
> the tuning lever, in spite of others' experience.  If course I do all the
> knocking down etc., including the tapping down of the strings on the
> bridge, for which I use a brass rod and a gentle hammer.  I also
straighten
> all wire before installing and never use it straight from the coil.  When
I
> come to the tuned partials, I do as much as possible with the lever and do
> a final evening out with the help of some pressure on the speaking length
> with a length of hardwood.  The knocking down also creates a shock that
> overcomes the static friction at the bridge-pins and causes the tension to
> level out.
>
> I should say I don't do outside tuning, let alone concert tuning, and I
> always use tuners to finish the job, but I think I'm probably better than
> must tuners at setting up a piano to stay in tune, simply by dint of
> experience in this stage of the work.  I am no match for any good tuner
> when it comes to fine tuning.
>
> >What happens to the partials and general overall sound characteristics of
a
> >string that has been over-stretched if this is indeed possible?
>
> In brief, it breaks, now, today or next week.  Good piano wire is
'elastic'
> up to a certain tension; that is to say that as tension is increased it
> will get longer but when the tension is removed it will return to its
> original length, like an elastic band.  At a certain tension, the wire
> reaches its 'elastic limit' and becomes 'plastic', like plasticene or
> spaghetti, at the weakest point.  This happens over a very small range of
> tension and your wire is no longer piano wire but very hard plasticene.
>
> The above definition of elasticity is what's taught at school.  When it
> comes to piano wire, it is not quite true, as I mentioned in another
> message a while ago, otherwise good pianos would only ever need one good
> tuning.  When you stretch a string, you are disturbing the internal
> equilibrium of the molecules.  They have, as all creatures aim to, found a
> place to be that is most comfortable.  You have wakened them up and they
> have to find a new comfortable position to settle down in, and this takes
a
> long time since all their fellow molecules are doing just the same
> thing.  The end result of this is that all the molecules do finally go to
> sleep again and that internal tension is removed.  The pitch of the note
> therefore drops and the tone at the same time improves.  So far as I know,
> there is no book that adequately describes this whole phenomenon, let
alone
> the improvement in tone.
>
> JD
>
>