treble wire breakage

[William R. Monroe]

Stephen,

>From my former life as an engineer, I respectfully disagree with this
reasoning.  Ideally, the strings will be operating in the elastic zone and
will be undergoing only elastic deformation - initially.  However, a small
amount of plastic deformation occurs, punctually, over time.  That is,
though most of the stretch is elastic, some is plastic and can not be
recaptured.  Though some strings may last longer than others with a
substantial amount of elasticity left in them, they all have been
plastically deformed.  These strings are therefore subject to breaking
relative to their usage.  Old treble strings are waiting to go.  Some more
than others.

William R. Monroe
PTG Associate
Salt Lake City, UT


----- Original Message -----
From: "Stephen Birkett" <sbirkett@real.uwaterloo.ca>
To: <pianotech@ptg.org>
Sent: Wednesday, May 01, 2002 2:18 PM
Subject: treble wire breakage


>
> Joe writes:
> > Either you haven't been paying attention or the ears are going. <G> The
Olde
> > wire has just spent the last 100years stretching/elongating/being
> > contaminated by god knows what and you say the treble strings do not
> > DETERIORATE! BS, they do and everyone who knows, knows that. Sheesh,
where's
> > your reason, man?
>
> Well this depends on a variety of factors. A string operating well into
> the elastic zone (i.e. far enuf from the plastic region), as it should be
> for a modern piano scale with high carbon steel wire, will undergo only
> elastic deformation, even with very hard playing.  I've seen enuf 19th
> century pianos with perfectly good >100 year old treble strings.
>
> The wire may of course deteriorate for other reasons: (i) environmental
> contamination - which is a particular problem for carbon steel wire, and
> may kill the wire quite prematurely - or (ii) design flaws which introduce
> stress that exceeds the elastic zone at critical points like bridge pins,
> agraffes, tuning pins etc, or (iii) design flaws that provide a scale too
> close to the plastic zone. I suspect that reasons (i) and (ii) are likely
> to be the cause of most breakage of modern piano treble strings.
>
> Now, going back another 100 years, you have non-carbon iron, and reason
> (i) tends to take on less significance. The stuff is remarkedly stable
> from corrosion etc. Reason (iii) is a function of scale design - the high
> quality builders knew how to keep their wire well away from the plastic
> zone. Schiedmayer talks about this and discusses the certain end of a wire
> that goes plastic,a nd the critical necessity to avoid this in scale
> design. For these old olde strings I would expect reason (ii) to be the
> most likely cause of failure. Even so, I've seen pre-1800 iron wire that
> would work perfectly well as treble stringing material.
>
> Stephen
>
> Stephen Birkett Fortepianos
> Authentic Reproductions of 18th and 19th Century Pianos
> 464 Winchester Drive
> Waterloo, Ontario
> Canada N2T 1K5
> tel: 519-885-2228
> mailto: sbirkett@real.uwaterloo.ca
>
>