treble wire breakage

[baoli liu]

Another factor I'd like to mention for wire breakage
is "metal fatigue"

Even within the elastic zone,the string will become
weaker and weaker after million times of bending and
twisting.

If we magnify the string as a long rod,the inner
construct ure ( metal crystal ?) of the string is
going to change due to year's of frequent  bending.
This is why the old  string is easy to break and
create dead sound.

Baoli Liu,RPT




--- "William R. Monroe" <pianowrmonroe@hotmail.com>
wrote:
> 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
> >
> >


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