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TECHNICAL^SUPPLY DEPARTMENT
William BraidWluteTecfimcalEditor
"Wild" Strings in Pianos, Their Causes
and the Remedies for This Condition
A String in This Condition Is One That Gives Out Beats by Itself—Draft and Hard-
ness in Piano Wire—Kinks and Kinking and "Dead" Bass Strings
SUPPOSE that no defect or imperfection
in the construction of a piano more justly
irritates the tuner then what is called a
"wild" string. Perhaps a "dead" string in the
bass is as bad from the standpoint merely of
tuning, but for pure out-and-out ability to irri-
tate the "wild" string has everything else dis-
counted. A recent and most interesting case
of "wild" strings in the treble of a piano
causes me to bring forward a discussion of the
subject, during which I shall be able to touch
upon the cause, phenomena and cure of defec-
tive strings in the wound or bass section.
When the tuner speaks of a string as "wild,"
he commonly means that it gives out beats by
itself, just as two strings out of tune with each
other give rise to beats. In factories where
much care is taken to turn out fine work the
tuners are instructed to remove all strings
which, by reason of this or any similar defect,
cannot be properly tuned. Unfortunately, how-
ever, in some shops this precaution is neg-
lected, so that the pianos go out into use in-
capable of being tuned accurately, even by the
most accomplished artist.
Almost every scale of which I have any
knowledge shows, from time to time this
phenomenon, where one string of the three in
an unison, when wedged off and made to sound
by itself, shows rapid and confusing series of
beats, often so rapidly and so confusing as to
baffle the tuner's best efforts at tuning the
unison accurately. The fact, however, that
these phenomena occur in different regions of
each scale, although always (or nearly always)
somewhere above C 64, suggests that the wire
itself may usually be to blame. This has in-
deed often been suggested, but very little in-
formation has been hitherto available on the
subject, so that most of the attempted explana-
tions have been, almost entirely, matters of
guesswork.
I
It is necessary to distinguish clearly between
a rattle or buzz on the one hand and a beat
on the other hand. A string which shows beats
when sounded alone evidently either is defec-
tive in construction or has been treated some-
how so that it acts defectively. There is evi-
dently no other kind of cause to be assigned to
the phenomenon, at least, within the bounds
of reason.
Draft and Hardness
Steel wire is drawn from rods by successive
drafts down to the final required size. As many
as a dozen or more drafts, successively through
smaller and smaller dies, may be necessary to
bring the wire down to its final diameter, and
to a large extent the quality of the product
may be measured by the number of the succes-
sive steps taken in drawing it down. For all
makes of wire known to me it may be said
that the quality is in direct proportion to the
number of successive drafts. Now, each draft
builds up the tensile strength of the wire,
which becomes very hard and must from time
to time, between drafts, be subjected to a proc-
ess of annealing. Since, however, the tensile
strength of all the best domestic and foreign
wires is near on the average to 400,000 pounds
per square inch, it is evident that the steel
filament is a delicate and subtle product requir-
ing care in manipulation and showing at once
the bad effect of rough handling.
It need hardly be said, of course, that the
stringer should be careful to follow the natural
curve of the wire and should not bend the
strings forcibly against it when he is passing
them around the hitch-pin and over the bridge
pins. If by any chance a length of wire is bent
backwards in the process of stringing, it will
be subjected, at the hitch-pin and at the coil
around the tuning pin, to a very great tensile
strain. Steel piano wire of whatever make is
very hard and very delicately tempered. It is
i&Ui 1 ICES
not intended to stand rough handling, and if
it is handled roughly will rebel, either by snap-
ping at a coil or by giving out beats. When
beats are thus given out it is not because the
backward-bent wire is annoyed, but because it
it unable rightly to fulfill its functions.
Bend and Beat
What then causes a backward-bent length of
steel piano wire to give out beats? If one
carefully examines such a piece of wire, by
means of a system of visual analysis, such as
the Ossiso supplies, one observes that certain
of the partial tones given out by it as it vi-
brates are far more prominent than they should
ordinarily be. Their amplitude is inordinately
large, and, what is more, some of them which
in a normal string do not at all come out show
themselves most plainly. It is evident from this
that the backward-bent length of wire is giving
out segmental vibrations of incorrect amplitude
and frequency, owing to certain fractions of its
length being strained at tensions higher than
other fractions have to sustain. This in turn
is due to the forcible twisting of the string as
it was put on the piano.
On the other hand, of course, good stringers
do not make these mistakes. If one watches
a stringer whose work is evidently being done
skilfully, but whose pianos, thereafter, show
these wild strings, one must conclude that
either the wire or the scale is at fault. If the
fault lies with the scale, then this is because
the string lengths are incorrect and the bearings
badly laid out. But in most cases the trouble is
to be sought rather in the wire. Either, then,
we must assume that the wire is unevenly
{Continued on payc 27)
William Braid White
Associate, American Society of Mechanical
Engineers; Chairman, Wood Industries
Division, A. S. M. E.; Member, American
Physical Society; Member, National Piano
Technicians' Association.
Consulting Engineer to
the Piano Industry
Tonally and Mechanically Correct Scales
Tonal and Technical Surreys of Product
Tonal Betterment Work in Factories
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