This document summarizes an article from 1925 about repairing and understanding the sounding board of a piano. It discusses the complex construction and materials of sounding boards and how vibrations travel through different parts of the board. It emphasizes that a well-constructed and properly repaired sounding board is essential for a piano to produce good tone. The document aims to educate piano technicians on the importance of the sounding board and how to properly diagnose and repair issues with it.

1. Sounding Board Repairing
Its Limiting Factors
By Charles Walter Beach, Springfield, MO
Published 1925
“Mr. Beach has given this subject thorough and scientific study, and this publication will be found of
great educational and practical value.” so says the editor of The Tuners’ Journal, Thomas J. O’Meara.
This booklet consolidates the six instalments published from October 1925 through April 1926 in The
Tuners’ Journal, under the above title “Sounding Board Repairing”. I hope this will be of interest to the
piano technician of today and of the future. I believe that there is something for every piano
technician in this historic article.

2. Instalment 1
October 1925 pp. 232-234
Without a complete, unbroken, unified sound
board any piano is crippled, if not useless, as a
musical instrument. A bad repair job on a
cracked or loose board fails to correct the
trouble, and often introduces distressing
rumbles, quavers, or reverberating splashes of
amplitudes untimed in their travels by improper
stresses, weights, or bracings created by these
repairs, which once produced are not easily, if
ever, overcome. Therefore, it is necessary that
the repairman know exactly what he is about
when he touches the sound transmitting-
amplifying apparatus of the piano.
Strange methods have been employed by tuners
to stop the queer rattles, tingles, raspings and
noises that accompany and indicate looseness of
ribs, cracks in the sounding board or loose edges
of the board, but frequently without restoring
the tone. Fullness of tone is one of the
characteristics of the pianoforte which has made
it so popular (forte means strong), and any
method that fails to return the parts to their
intended relationship one to the other is likely
to create a condition of restriction, if not of
complete imprisonment, of sections of the
board, thus rendering parts at least of the
stringed “harp” of the piano dead!
Some samples of insufficient repairs which I
have found include cork and wooden wedges
between the ribs and the board, between the
ribs and the stanchions, between the board and
the plate, between the edge and the frame of
the case; cords tied tightly across from screws
in the board to the posts or the frame; shims
driven or glued into widely parted ribs (which
should have been drawn back together); screws
in the ribs and the board for which holes had not
been drilled; screws too long or too large for the
places; too many screws in a given section;
failure to have parts firmly together when
screws were driven; overhauled screw holes and
screws too small for the holes drilled; and even
in otherwise good repairs an unsymmetrical
distribution of screws. While there are times
when cork may be inserted in places to stop
rattles which the owner will not pay to have
removed in the right manner, and shims may be
used with certain restrictions that make them
almost prohibitive, yet both methods create
restricted areas.
Many questions as to the how and why of this
matter may be answered by considering a few
basic facts in regard to the nature, ideal
condition, purpose, and method of
manufacturer of the sound board of the piano.
The following interesting facts are collected
from many sources and are respectfully
submitted to the Naptincs (member N.A.of P.T.,
Inc., a word coined by Edgar L. Seagrave,
president emeritus, St. Louis division) to inspire
them, if possible, with a greater awe for the
wonders which man’s ingenuity has produced in
the piano and the wonders each may learn to
bring about in the instruments entrusted to his
care, through a better understanding of the
elements of which the piano is made.
The sound board of the modern piano is made of
selected, straight-grained, flawless, uniformed
textured, mountain grown wood from coniferous
trees sixty to a hundred years old. It is seasoned
to the point most susceptible to vibrational
transmission, yet at the same time retains an all-
essential elasticity of molecular constituency,
supposedly “quarter-sawn,” etc. All of these
exacting conditions mean that only a small part
of the collected wood proves suitable for use in
high grade pianos. Such pieces as do pass are
narrow, sometimes not more than three and
one-half inches wide, necessitating one of the
great tasks of the piano-maker’s art – the fitting
together of many parts, with the grains often so
closely matched that keen eyes can scarcely
detect the joining. The reason for such care
should become more and more evident as this
account progresses.
To enable this comparatively frail wood to bear
the strain of the tension placed upon it by the
strings of the piano, the pieces have to be fitted
upon an arch, and to them are glued “ribs,”
primarily for the purpose of strength, but to
serve also another very great purpose, that is,
the equalization of the possibilities of
directional vibrational velocities.
By experiment, Tyndall, Wertheim and
Chevandier discovered that in wood, sound
travels along “three unequal axis,” and the

3. different velocities have actually been
determined for the various kinds of wood. Not to
burden this article with figures, it is enough to
say that the velocity along the grain is about
three thousand times across the largest sounding
board in one second, or about three miles.
Across the grain, that is, along the “ring,” the
speed of transmission is only about one-sixth as
fast, while across the ring, which, if the board is
made of quarter-sawn fir, would be across the
grain on the width of the sections, the velocity
has been found to be about one-third of that
along the grain, or fiber. It is thus to be observed
that the relative speeds are approximately
expressible in the figures “one,” “two” and
“six.”
Bad construction of the ribs, faulty materials,
careless gluing of the ribs, and other faults in
connection with the rib assembly, have created
many dull pianos, - to the unproclaimed shame
of their makers. Over all this board-rib-bridge
assembly has been placed a shield, in some
makes an almost penetrating protective coat of
especially prepared varnish, to seal up the glued
edges from the dissolution-working effects of
wet and dry climates.
As to the traveling of sound in the sound board
of the piano, John Tyndall, in his fifth edition of
Sound, page 78, says:
We are now prepared to appreciate an extremely
beautiful experiment, for which we are indebted to
Sir Charles Wheatstone.
In a room underneath this, and separated from it by
two floors, is a piano. Through the two floors passes
a tin tube 2 ½ inches in diameter, and along the axis
of this tube passes a rod of deal (wood, either fir or
pine, ed.), the end of which emerges from the floor
in front of the lecture table. The rod is clasped by
India-rubber bands, which entirely close the tin tube.
The lower end of the rod rests upon the sound board
of the piano, its upper end being exposed before you.
An artist is at this moment engaged at the instrument,
but you hear no sound. When, however, a violin is
placed upon the end of the rod, the instrument
becomes instantly musical, not, however, with the
vibrations of its own strings, but with those of the
piano. When the violin is removed, the sound ceases;
putting in its place a guitar, the music revives. For the
violin and guitar we may substitute a plain wooden
tray, which is also rendered musical. Here, finally, is
a harp, against the sound board of which the end of
the deal rod is caused to press; every note of the
piano is reproduced before you. On lifting the harp so
as to break the connection with the piano, the sound
vanishes; but the moment the sound board is caused
to press upon the rod the music is restored. The sound
of the piano so far resembles that of the harp that it
is hard to resist the impression that the music you
hear is that of the latter instrument. An uneducated
person might well believe that witchcraft or
“spiritualism” is concerned in the production of this
music.
What a curious transference of action is here
presented to the mind! At the command of the
musician’s will, the fingers strike the keys; the
hammers strike the strings, by which the rude
mechanical shock is converted into tremors. The
vibrations are communicated to the sound board of
the piano. Upon the board rests the end of the deal
rod, thinned off to a sharp edge to make it fit more
easily between the wires. Through the edge, and
afterward along the rod, are poured with unfailing
precision the entangled pulsations produced by the
shocks of those ten agile fingers. To the soundboard
of the harp before you, the rod faithfully delivers up
the vibrations of which it is the vehicle. The second
sound board transfers the motion to the air, carving
it and chasing it into forms so transcendently
complicated that confusion alone could be
anticipated from the shock and jostle of the sonorous
waves. But the marvelous human ear accepts every
feature of the motion, and all the strife and struggle
and confusion melt finally into music upon the brain.
My reason for introducing the above quotation at
this time is that there are two well-defined
schools or classes of makers: those who believe
everything depends scale and string quality with
very little importance attached to the sound
board (with seemingly good authority back of
their attitude and support by such illustrious
men of the piano world as Alfred Dolge); and
those who contend that the sounding board is
the supreme determinant of tone. A
combination of the two classes is found in one
maker who has succeeded in producing the most
wonderfully toned pianos in existence today.
The above “deal rod” test proves conclusively
that the vibrations travel in every direction
through the sound board, else how could they
come from many positions in the bridge, through
the rod and up into the second amplifier
(transducer – ed.), in the form of violin, guitar
or harp? The very nature of vibration itself is an
important consideration to the tuner-repairman,

4. and upon a true understanding of the foregoing
and the following facts depend the “do’s and
don’ts” of the directions which are given in
another part of this treatise, “Diagnosis of
Trouble.”
A misunderstanding or a misapplication of a
principle or law may be at the bottom of many
disagreements in regard to things scientific, and
because of this I ask a bit of indulgence from
those who might wish to dive promptly into the
heart of repairs.
In Pianos and Their Makers, Alfred Dolge
concludes that, because one Seigfried Hansing
shows the fallacy of the “wave theory” in wood,
the sound board does not give off sounds. It is
my intention in the next section to show that Mr.
Hansing was right in one respect but wrong in
another which vitally determines our procedure
in repairing the board, even making possible an
understanding of this mysterious thing called
“vibration.’ Oscar Paul’s belief that the
sounding board was the soul of the piano was not
far amiss. The very “empiric experiments”
employed by Mr. Dolge and his co-workers in the
famous old Mathushek factory actually prove the
point, as I shall show, their opinions to the
contrary.
Just as a chain is no stronger than its weakest
link, so the piano is no better than its worst
element. Every item has its direct and indirect
influence upon every other. Waves such as travel
in the air and upon the water are not found in
wood, but there are amazing similarities
between the two. Upon these similarities
depend that wonderful factor “amplification,”
which will also be explained in detail in
“Diagnosis of Trouble” with its practical
significance outlined.
Let us suppose, for the purpose of illustration,
that we could have a piano with perfect strings
and an ideal scale – which would include the best
choice of action, placed to strike at a point to
quench the objectionable partials, nicely
explained in Mr. Antunes’ article Voicing (in the
Tuners’ Journal June, July and August 1925),
and with such voicing as only a man of his
understanding could do. But if the sound board
of this piano lacked excellence of workmanship
and material the greater portion of these
valuable elements would be lost, because the
lack of amplification in such an inferior board
could not be compensated by any other quality
of excellence.
On the other hand, if a piano had strings of
unequal elasticity, improper reserve ductility,
unequal size within a given length, and
consequently incapable of being purely tuned
because of irregular nodal points which often set
up beats within the single string, no manner of
excellence in the sounding board could offset
such a lack. Such a piano would practically be
bereft of overtones, which Helmholtz
determined were a large part of the tonal timbre
or “klangtint” of the tone of the piano.
A poor sounding board is so irresponsive, “stiff”
and insensitive, we might say, that it does not
properly amplify either pianissimos or
overtones. The only reason for these conditions
is that cheap makers do not know how to
produce mechanically correct instruments,
while the wise ones know the vast importance of
little things.
Instalment 2
November 1925 pp. 279-281
Vibration
Its Part in Amplification
The nature of vibration and its aid in
determining the exact location and extent of ills
existing in the sound board will be my next
topic. The task of selecting from an
accumulation of material better suited to be set
forth in a volume only such things as befit the
purpose and scope of a small treatise such as this
is not at all easy. I have tried, however, to
arrange the material so as to make the steps
taken appear almost self-evident, without the
need always of quoting from or referring to
authors.
In order to understand the nature of vibration it
is necessary to consider the molecular theory.
All matter is said to be composed of molecules,
particles so small that the most powerful
microscope cannot make them visible. Each of
these is still further subdivided into atoms,
which are in turn made up of electrons, with a

5. nucleus of electrons of one type of charge,
positive or negative, around which circle
electrons of the opposite charge. Electricity is
thus given credit for being the fundamental
oneness at the bottom of the universe, the
secret of which is buried in the heart of matter
itself so deeply that man can never hope to
discover it. The mass of an electron is 1/1845 of
that of the hydrogen atom which is the lightest
known. (Practical Physics, Black and Davis, page
305.)
The grouping of molecules, the density, and the
molecular attraction within solids, varies so
greatly that the amount of strength or resistance
to outside influences differs in various
substances to such an extent that, aside from
actual differences in physical content,, there
are notable variations in structure in different
woods, some of which are entirely unfit for use
in musical instruments. “In regard to sound and
the medium through which it passes, four
distinct things are to be borne in mind –
intensity, velocity, elasticity, and density.”
Sound, Tyndall, page 74.
Air is known to be made up of so many particles
per thimbleful that man could not count them in
a lifetime. To express the number of these
particles held by atmospheric pressure against
the sound board of a piano would require a string
of figures from NY to Chicago. These particles
are in a high state of agitation, or commotion,
all the time. Air has one quality common to all
gases, unlimited expansion. This quality makes
it the most elastic of familiar substances and the
most sensitive to agitation, though not the best
adapted to the speedy transmission of sound, as
will appear from statements of facts ascertained
by scientific experiments soon to follow:
Scientific education should teach us to see the
invisible as well as the visible in nature, to picture
with the vision of the mind those operations which
entirely elude the bodily vision; to look at the very
atoms of matter in motion and at rest, and to follow
them forth, without ever once losing sight of them,
into the world of the senses, and see them there
integrating themselves in natural phenomena. With
regard to the point now under consideration, we must
endeavor to form a definite image of a wave sound.
We ought to see mentally the air-particles when urged
outward by the explosion of a balloon crowding
closely together; but immediately behind this
condensation we ought to see the particles separated
more widely apart. We must, in short, be able to seize
the conception that a sonorous wave consists of two
portions, in one of which the air is more dense, and
in the other of which the air is less dense than usual.
A condensation and a rarefaction, then, are the two
constituents of a wave of sound. – Tyndall Sound, pp.
35-36.
Condensations and rarefactions as just referred
to have their characteristic differences
depending upon the medium through which the
vibration or shock is to travel. With a few
exceptions, which are due to restricted
elasticity, the greater the density of the matter
through which a sound is to travel, the smaller
is the amplitude of the wave, but the more
swiftly will the impulse between particles be
imparted, and the more velocity will the sound
have as is noted by comparing the following
data:
Velocity of sound in air… 1090 + feet per second
Velocity of sound in water … 4714 + feet per second
Velocity of sound in fir… 15,218 feet per second
Velocity of sound in steel… 16,023 feet per second
These figures would have to be revised for any
great variations in temperature, compression or
affected densities, and therefore serve only
roughly. There are variations in elasticity that
greatly affect the velocity of sound in matter. It
is due to the solidity of molecular constituency
of fir combined with its wonderful elasticity that
it is so satisfactory a material for the
amplification of sound in pianos.
A common error of those who have considered
the nature of the transmission of sound through
the sound board has been to expect to find the
board divided up into undulations of perceptible
size. Upon such a misconception hung the
announcement by Seigfried Hansing that there
were no “waves of sound” within the sound
board. This also led to the assertion that it was
‘tremors” in the board which excited the air
with transmitted shocks which were carried to
the ear drum, and thence to the nerve centers
of the brain, where the mind recognized tones –
music. The same failure to learn the exact
limitations of the thing called vibration brought
Mathushek and Moser to the conclusion that

6. there were no transverse waves in the sound
board. The gluing of two sound boards together
with the grain in one running across the grain in
the other was the specific example that
convinced them.
The motion of the sonorous wave must not be
confounded with the motion of the particles which at
any moment form the wave. During the passage of the
wave every particle concerned in its transmission
makes only a small excursion to and fro.
The length of this excursion is called the amplitude of
the vibration. – Tyndall, Sound, page 73.
The argument that the sound board does not
give off sound is an exact parallel to the old war
horse of debate: if a great tree were to fall in
the forest out of the range of any ear, there
would be no sound. Any of us can contradict,
reverse and restate any fact, but often with a
ludicrous inclusion of ideas just “refuted.”
If my wife says, “You are letting the cold air in,”
and I correctly reply, “My dear, it is only the
radiation of heat from your own body that gives
you the sensation of cold air striking your body,”
the essential facts have not been changed in any
way.
We can likewise be captious in regard to the
phenomena of sound. All intelligible definitions
of sound include the idea of transmitted shocks
impressing themselves upon the ear drum and
there being translated into “noise” or “music,”
determined by the origin of the shock.
In this connection there are so many
considerations that it is impossible always to
appear perfectly logical. We are in the midst of
a field of interrelated elements that are
inseparable one from the other. To follow one
element very far would take us away from others
just as important, so we must return to the same
facts under slightly varying phases or contact
with those around it.
The limitations in our vision and perception,
through the nervous system of our bodies are
responsible for our capacities for enjoyment. If
we could see the horrible organisms we daily
consume – microbes, bacteria, etc. – our lives
would be miserable. If we could feel every shock
of the strings of the piano, that is, if our
perception-limit were as fine as one-thousandth
part of a second instead of about one-twentieth,
the individual shocks would not blend into
musical tones, except such pitches as are of
proportionately higher frequencies. Our whole
realm of music would be upset. That the limit of
human perception is about one-twentieth of a
second is easily demonstrable by anyone who
cares to go to the trouble.
To prove this point to my own satisfaction, I
made three small and light reproducers, so that
their weight would not cause the disk to drag,
and tried them at various distances from each
other in the same groove on the record. By using
specially constructed points I could cause them
to approach as closely as one-half inch of each
other. By computing the velocity of the
revolving portion of the groove between the
points, I found that the difference in the instant
of attack when the time limit was as small as
one-fortieth of a second was less than is
observable in ensemble at most concerts, while
a variation of even as wide as one-sixteenth of a
second was not at all offensive. The truth is that
the error in delivery found in a very large chorus
ensemble is often as great as one-seventh of a
second.
The importance of the truth just stated is
greater than it appears at first. That our limit of
perception is low in comparison with the
tremendously swift travel of impulses through
matter is an auspicious guard or mother of the
whole phenomena of amplification. The very
spaces that are known to exist between the
molecules of matter permit them to bump
against one another in multiple fashion so that
the molecules transmit many rates of frequency
at the same time.
This is not nearly so marvelous in the sound
board as is the transference taking place within
the needle of the phonograph. Here at the same
instance are imparted through the same
molecules, by means of infinitely varied
parabolas, ellipses, circles and zigzags, all
within millionths of an inch of cubic area (if only
some way to record the same could be devised!),
textures, pitches and forces with the current
noises of the entire orchestra, then on to the
diaphragm, where a similar transference of
motion, in less than one-thousandth of a second,

7. is spread to all the molecules of the mica, which
in turn give their peculiar motions to the
particles of air. This, as before stated, is so
infinitely elastic as to expand indefinitely and
yield and rebound to every slight impulse; and
there the motion is conducted in one direction
through an ever-widening “hallway” with shocks
very many times multiplied, both by reflection
and molecular group-shooting to the outside,
where our ears are literally bombarded with the
accumulated and augmented “sounds-to-be” at
the threshold of intelligence. The entire
transference of action here described takes less
than one-five-hundredth of a second to
complete. Our poor gray matter is moulded by
at least twenty-five repetitions of the process
before we awake to the reality, which is no
disgrace.
Instalment 3
December 1925 pp. 335-337
More About Amplification
Its part in tone
In the previous section we considered the
molecular theory, and how it enables us to
understand why and what is amplification. We
also found out that it is easy to be led astray
“scientifically” unless we are very careful to
base all conclusions on facts.
In this section we shall go more deeply into the
actions of the molecules of the board when
amplification takes place, using the imagination
in keeping with known facts, to let the mind’s
eye see an endless variety of possibilities within
the compass of a space almost too small to
measure.
In the same manner that the distinctive
movements within the particles of the needle
and its diaphragm characterize the sounds given
off, so do the molecules of the sounding board
give off faithful transcriptions of the rates of
vibration and peculiar regularities or
irregularities of the elements concerned in their
production, namely, string texture, age,
elasticity, the conformity of striking points to
law, the susceptibility of the bridge to
transmission, the board’s homogeneity or its
lack and its elasticity, uniform or irregular.
The ideal combination of these and all other
essentials constitutes “fine” tone. These
movements of the small particles of the sound
board surge with such speed that for every
impulse delivered by the fastest vibrating string
in the piano (about 4,000 per second) the shock
reaches every molecule in the instrument. The
present sizes of the sounding boards that have
proved most satisfactory follow the line of
average wave-length from the greatest number
of positions upon the bridge, which are the
origin of impulses. The law of reinforcement by
regularly repeated impulses, which includes also
the manifestations of interference when
distance does not accommodate well-timed
reflections of vibrations, comes powerfully into
play in this instance – making beautiful volume
in certain parts and smothered effects in other
parts of the same piano harp, if the relationships
of constructural detail are not well disposed.
A well-known illustration of the power of
repeated impulses is that of a dog trotting over
a great bridge and setting it into violent motion.
A recent demonstration of this principle ended
disastrously when a dance hall in Carolina
(South?) collapsed under the continuous
rhythmical shocks delivered by the major part of
the dancers doing the “Charleston” undulation
in unison.
Consider now that the separate pieces of the
sounding board are assembled with the grain
running about parallel with the treble bridge,
from corner to corner of the piano in the
upright, from “point” or rear left to high treble
portion in the grand. This design is of great
significance. The best toned pianos always use
this form and will always do so for the reasons I
shall now state.
The speed of transmission of the shock along the
grain was given as six times that across the rings
which would be through the thickness of the
board. (from three-eighths inch in the treble to
as thin as one-quarter inch in the bass, according
to Alfred Dolge), and so not to be considered,
while three times the velocity along the rings,
which would be across the pieces, that is, across
the grain. As the distance from the center of the
bridge to the edge of the piano straight across
the grain (in the widest part) is about one-half

8. of that from the same point on the bridge to the
corner, and since there is a quantity of straight-
grained wood in the ribs so closely assembled to
the board, through the glue man’s art, that it is
really an integral part with many of their
molecules held firmly against the molecules of
the main part of the board, and as the ribs are
about twice as thick as the thickest part of the
sound board, there are enough fibers within the
ribs to be equivalent to from thirty to fifty
percent of the total volume in the sound board.
The travel from bridge to edge and return is
fairly equalized in velocity with that to the ends
and return. The board narrows almost to the
same degree that the wave length is shortened
through the higher frequencies of the tones
ascending, while the width is increased greatly
toward the end of the slower rate tones which
have the greater wave lengths. The problem is
such as never to permit the perfect solution.
In every case, amplification (the making of full
volume) is multiplied transference of action,
enlargement of the field of applied forces or
motions, increased volume of affected areas of
agitated, transmitting or reflecting substance.
The transmission of sound through a solid depends on
the manner in which the molecules of the solid are
arranged. If the body be homogeneous and without
structure, sound is transmitted through it equally well
in all directions. But this is not the case when the
body whether inorganic like a crystal or organic like a
tree, possesses definite structure. – Sound, Tyndall,
p. 69.
The uniformity of arrangement in structure
along the fiber of fir wood accounts for the
greater speed of the traveling vibration, while
the little paddings of resin between fibers, and
the layers of resin between the rings of growth
contribute largely to the great elasticity of the
wood, though retarding the vibration
transference across the grain. Let us trace the
actual happenings within the board as
amplification takes place. We have a “rude
shock” delivered through the string to a rather
stiff and unresponsive bridge, which rests upon
an elastic foundation, the sound board. Its
molecules are violently agitated and the impulse
is carried to the edges of the board, where the
firmly anchored edges constitute a wall from
which the shock among the particles is reflected
back over the path of its arrival, returning to the
center of agitation at the same instant that the
second impulse starts. The force of the first is
added to the second and the augmented impulse
again goes to the edges of the board where it is
again reflected with small loss, again arriving at
the place of origin as another impulse is given or
added. This same process is repeated as often as
the frequency of the vibration of the string that
is struck. In a perfectly proportioned board
there would be but an imperceptible variation
from the exact rate of each tone with reference
to its reflected reinforcements. These built up
amplitudes actually cause the board to heave
and sway, motions that can easily be felt by
putting the hand against the board while
someone is playing. These very heavings of the
board proclaim the presence of foreign matters,
or loosened ribs or edges of the sounding board.
Any thing that hinders the free movement of any
section of the board restrains or destroys the
normal amplitudes that should be developed at
such points in the board. Because of this fact
there are some insistent laws governing the
methods permissible in the repair of a sounding
board, which will be stated later on.
Music is primarily composed of mathematical
and symmetrical tone lines, wave length
combinations that impart impressions in their
own likeness upon the receptive mind. We
should not be surprised now to learn that
investigations by Chladni revealed the fact that
all vibrating bodies assume within themselves
various symmetrical designs in the distribution
over their surfaces of the areas of greater and
lesser agitation, depending upon the source s of
excitement and the places of interference. This
law holds in wondrously complicated form in the
diaphragm of the reproducing machines and in
the sounding board of the piano.
In this fact lie the reasons for the prohibition of
the use of shims and the specific use of screws,
which will be dealt with in the next section.
Instalment 4
February 1926 pp. 416-419
Reflections; Symmetrical Lines of
Comparative Quiet – Defining Figures;
Interference; Diagnosis of Trouble

9. To gain a better impression of the relative
importance of this subject, it will prove
profitable to take a brief inventory of the
matter.
Music is one of the greatest forces in modern
life. The piano is the most popular instrument of
the “play-it-yourself” type. It is the one the
foundational requirement in many courses of
musical education, one to three years of piano
study being required for graduation in other
instrumental courses.
In all musical instruments there is some means
of enlargement or amplification of tone, such as
a sounding board, a resonator or an expansive
“hallway” for multiplying the reflected
vibrations and condensing them all in one
direction. The audion vacuum tube has
revolutionized amplification in some
instruments, though it is only an example which
bears out the statement that too much
importance cannot be attached to the problem
of true and rich development of the tones of
musical instruments, and of pianos in particular.
Due to the influence of climate, of which
changes in humidity play so vastly important a
part, sounding boards are often much changed
from their original dispositions. Men of wide
experience recognize that pulling apart of fiber,
looseness of ribs on the sounding board,
loosened bridges, etc., are grave troubles and
prevalent to a sufficient extent to demand
considerable attention.
This series of articles has been devoted so far to
the laws underlying the construction of the
sounding board, so that the conclusions reached
may come to the reader naturally.
A mastery of these principles by the piano
mechanic will lead to far greater efficiency, will
materially increase his earning capacity and
prestige, and besides will remove one of the
most evasive causes of “dissatisfaction” with his
tuning, as many s good tuning has been wasted
on a piano in which the need of sounding board
work was undetected by the unsuspecting tuner,
and once neglected the tuning was usually lost
to him for all future time. I know that in my own
experience I could not succeed without this
knowledge. A fair part of my earnings comes
through the correction of faults found in some
part of the sound amplifying apparatus of the
piano. The present article deals with knowing
how to find the trouble, and should be given
undivided attention.
Usually much confusion is attached to the words
“vibration,” “tremor” and “wave” and for
perfect clearness we must consider a limited use
of these words and their absolute relationships.
A “vibration” is started with an original impulse
which in the very nature of the entire
instrumental ensemble would not make enough
headway against such overwhelming obstacles as
the inertia, strength and relative immensity of
the board-bridge assembly to produce a
“tremor” until perhaps five or ten repetitions
had built sufficient amplitude to be felt. The
“wave” is the outward surge of the impulse; it
embraces every particle of matter affected till
the arrival of the next impulse, which may
coincide with or overlap in varying degrees the
reflection of the first or immediately preceding
impulse, single, double, triple, etc., depending
on the frequency, or pitch, of the origin of the
impulse. Vibrations and tremors are not
coincidental except in the lowest tones, where
elements are great and natural periods are slow.
Tremors are the results of vibrations, a sort of
manifestation of vibration translated into areas,
but they may have periods of much slower
frequency than the vibrations inducing them, as
I expect to demonstrate under a different title
at a later writing.
By way of emphasizing the fact that nothing is
too small to be considered in insuring the
integrity of the sounding board of the piano, I
quote from Alfred Daniell’s text book, Principles
of Physics, chapter XIV, page 455:
When a beam of light or radiant heat falls upon a body
capable of absorbing heat, that body becomes
warmed and expands. A flash of light produces an
instantaneous expansion, which immediately dies
away. An intermittent beam produces a succession of
expansions and contractions; in other words, the
surface of the body vibrates. The amplitude of its
movement may, with beams of light of moderate
intensity, exceed the ten-millionth part of a
centimeter. Lord Raleigh has shown that this
amplitude is sufficient for the production of sound;
and the power of converting the energy of an

10. intermittent beam of light or radiant heat into that of
a sound has been shown by Prof. Graham Bell to
belong to all matter, with a few doubtful exceptions.
If an intermittent beam be focused upon a mass of
lampblack, at each flash of light it becomes warm,
and the air within it, is dilated; if it be contained in a
test tube, the open end of which, is connected with
the ear by an India rubber tube, as the successive
flashes produce successive dilations and pulses in the
air, these pulses are perceived by the ear as sound; if
the lampblack be contained within a resonator, the
frequency of whose natural vibration is equal to that
of the frequency of the successive flashes, the
resonator emits a loud sound, audible at a glance.
I quote one more point of great interest from the
same text, page 466:
The movements of the drum of the ear are
astoundingly small. The greatest displacement seems
to be about 0.1 mm. or 1/250 of an inch. A sound
produced by an F# (181) pipe under an air pressure of
40 mm. of water can be distinctly heard at a distance
of 115 meters (127 yards). Topler and Boltzman
calculated that at such a distance the movements of
the air must be reduced to .00004 mm.; but those of
the more massive drum, with its appendages, cannot
be more than .000,001 mm., or the twenty-five-
millionth part of an inch – an oscillation so minute as
to be beyond direct microscopic observation.
In view of the many facts herein and previously
given, it can easily be imagined that the
sounding board of the piano vibrates in almost
infinitely varied forms. Every tone produces its
individual difference in distribution of agitation,
having high and low points of excitation, which
are greatest in amplitude where the appositional
outward surges and the returning reflections of
the previous vibration meet. All combination of
tones, such as chords, arpeggios and scales,
describe their own ever-varying designs of
peculiar disturbance.
The amplitudes of these vibrations are
determined by the force of the impact of the
hammer against the strings, and the wave length
is determined by frequency. In many parts of the
same board opposing influences may arrive at
the same instant. The result of their combined
energies is the production of conflicting “waves”
inn the sounding board movement, constituting
the condition known as “interference,” which is
present to some extent in even the best
constructed pianos, and in badly constructed
pianos brings about a comparatively great
nullification of amplification. The extent to
which a maker succeeds in constructing a board
which permits a great preponderance of
favorable, appositional generations of
reflections coalescing with arriving impulses
spells his success in producing fine tonal
volume, other elements having due attention.
For all these reasons, every portion of the sound
board, except the edges where support is given
to the arch, must be able to respond freely in
the transmission of impulses.
To get some idea of the intricacy of designs
possible to be generated by the transmission of
sound waves in the sounding board of the piano
see the copies of Chladni’s Figures, produced by
agitating square plates, some of them held at
their centers, and touched at various points
about their boundaries, thus creating various
lines of interference, whose “nodes” and
“internodes” of commotion have arranged the
sand to form the designs. (From Tyndall, Sound,
pp. 171-173.)
Effects of combinations of various frequencies
are simply shown in diagrams from Spinney:
<drawings of various wave forms from Spinney
Text Book of Physics, 1925 edition. Pp. 476-477>
The outcome of all these manifestations
peculiar to the sound board is that we are able
to recognize ailments by their symptoms the
majority of which I have outlined as follows:
Short loosened places along the ribs in the
central portions and in the high treble, short
loosened places in the top of the board, and long
cracks not wide enough to be seen readily unless
the eye be directed to them assert their
presence by queer little wheezes and sometimes
by a “tingle” in the tone that is also
accompanied by a notable weakness. People
with pianos so affected often say, “I wish you
would take that pin out of the piano. See how
funny it sounds!” Do not confuse this with
“sympathetic vibration” or “tuners’ ghosts,”
and remember accompanied by a notable
weakness.
A bridge that has come loose usually rattles,
though sometimes its call to you is, “I’m a

11. gourd,” or “I’m a cellar door” – hollow like, you
know! Badly parted ribs, very long loose edges,
loosened corners and completely loosened lower
bass bridges assert themselves by rattles, except
when too badly warped, and then there is an
easily discernible slumpy, mumpy, dumpy,
tubby sort of tone.
There should now be no doubt of the need of
making the repairs as nearly “low loss” as
possible. Shims inserted into cracks in the board
itself, unless it is easy to see that the board was
not properly seasoned in the first place, are
hardly advisable, because of the possibility of
some period of prolonged excessive humidity
swelling the board enough literally to crush out
the elasticity of certain weaker portions of the
board. If cracks exceed 1/16th
of an inch in
width, as is sometimes the case, shims are to be
used in the board itself, otherwise they are filled
with a composition which will be described
later. Shims never should be inserted between
the ribs and the board on account of the extra
bracing they exert. If the gluing of shims is
perfectly done they actually constitute an
architectural restriction to elasticity along that
particular rib, and if not perfectly done they act
as a positive damper upon transmission of the
tone in that section. Screws should be as small
as possible to insure perfect holding and the
rib=board connection should be triple-drilled to
avoid creating “islands of increased density” and
thus rendering their location a dead obstruction
to the vibrations perhaps from some much used
section of the instrument.
The strongest interval to use to bring out any
defect in amplification is the ”perfect fifth.”
Instalment 5
March 1926 pp. 462-464
Next to the choice of materials, and design and
workmanship, the gluing and preserving of the
sounding board of the piano are of almost
incalculable importance. Barring undue
exposure, abuse and accident, the secret of
durability lies in the excellence of the gluing and
the coating of the shellac and varnish. In the
preceding sections the necessity of fine material
and workmanship to produce a board capable of
correct amplification was made clear. It is now
my purpose to outline a manner of making
speedy, efficient, complete repairs which
restore strength and quality to boards that have
lost these qualities, and to prevent the
reappearance of troubles.
The method I use is not entirely of my own
devising. The principles developed in this series
were given to me in brief form by one Albert
Williams, a piano and pipe organ expert with
whom I made a providential friendship about
fifteen years ago. He was a piano rebuilder who
knew the value of indirect advertising, and was
a past master in the art of soliciting work, with
the ability to convince as to a piano’s needs, and
with a knack that enabled the customer to
forget about the “cost” of the proposed repairs
in consideration of the ideal condition into
which he was suggesting that the owner
“desired” him to put the instrument. Mr.
Williams was a psychologist who left the
conviction with every one for whom he tuned
that he loved his work so much that he could not
leave anything partly finished, and he compelled
notice of the extras he put into his work as “good
measure,” not boastfully, but tactfully. To him I
owe more than I ever shall have the opportunity
to repay, since he came to an untimely death in
Clarksville, Tennessee, in 1914, in a church
where he was installing one of his own pipe
organ blowers.
He was also one of those men who believe that
the sounding board of the piano could still be
improved. He told me of a board he had
constructed upon scientific principles, with
dimensions, shape and size best suited to
accommodate the velocities and rates of tone
vibrations, the boundary of which board he said
was oval (His board was left in storage in Topeka
Kas., in 1909, and was not patented because of
immature plans concerning a factory he
intended to build for the manufacture of his
own boards and blowers.) I mention this merely
to indicate the nature of the man from whom I
got my inspiration to improve the amplifying
qualities of every piano I find in need of such
attention.
During a period of fifteen years I have worked in
the same territory, with opportunity to observe
closely a great number of pianos and to know the

12. conditions under which practically all of them
were kept. Those pianos which received the
greatest care in their manufacture held and do
hold tuning best, stand up under the
unavoidable differences in humidity and
temperature and develop the fewest troubles in
sound amplifying apparatus. Conversely, the
products of haste and commercialism pure and
simple sometimes come unglued before they
reach their first “consumer.” One exception I
wish to note: no excellence in material and
workmanship can withstand erosion, which some
owners actually promote under their own roofs.
Moisture plus freezing causes the finish to flake,
break minutely, crack, then peel, and leaves
future attacks of the same process freedom to
dislodge glue joints, and finally to sever all
severable parts. If the surface of the finished
board feels rough to the touch, be sure that the
piano has been subjected to alternating periods
of warm dampness and freezing spells. For these
reasons I feel that a few words about glue and
varnish may be in order.
Much misunderstanding prevails in regard to the
nature and use of “glue.” Many mechanics seem
to think that “lots of hot glue” boiled over and
over again and again in the same old dirty pot is
“the dope.” That glue has great strength is
another misconception. If strength were an
inherent quality of glue itself it would not be so
notably true that the best cabinet makers and
piano men leave as little as possible in a
perfectly made joint.
Glue is a gelatinous substance extracted from
the skins, scales, hides, bones and connective
tissues of animals and fish. Its molecules are
very fine and of a very low rate of vibration,
having a high degree of intermolecular
attraction, but a still greater affinity for other
materials, especially for porous substances such
as leather, cloth and wood. The stickiness of
glue is due this fineness of consistency plus its
molecular attraction within itself. Its aptness for
holding other things together is the affinity for
other substances, scientifically called
“adhesiveness.” Too much boiling can destroy to
a great extent this prized quality in glue. The
report of O. Linder and E.C. Frost before the
1914 meeting of the American Society for
Testing of Materials pointed out that
“overheated glue is found to be weakened forty
per cent to fifty per cent.”
The Madgeburg hemisphere test, performed in
1650 before the German emperor by Otto von
Guercke, illustrates the next point I wish to
make. If we completely exclude the air from
between the joints with glue we are practically
utilizing the marvelous force of atmospheric
pressure to hold the parts together. It required
sixteen large horses to pull apart these twenty-
two inch “hemispheres,” perfectly fitted
together and then pumped free of internal air to
create as near a vacuum as was then possible.
(See Practical Physics, Black & Davis, pp. 101-
102.)
In this one element lies the reason for having the
glue hot. It will find its way into the pores of the
wood and make an absolutely air-tight joint. In
the same report of Linder and Frost it was
brought out that blocks of wood glued and
tested for the strength of glue required from
1,100 to 1,950 pounds to the square inch to pull
apart. These blocks were clamped together
after the manner of cabinet making, and
therefore were glued by means of what might be
called a hair line joint. In all successful sounding
board gluing every particle of glue that will
squeeze out from between rib and board, bridge
and board, or edge of board and frame must be
forced out, so as to permit the actual touching
of the molecules of the two parts to be glued
together. The greatest care must be exercised
to have the pressure uniform throughout the
length of the parts being glued.
Scientists consider resin, the principal
ingredient always found in varnish, nature’s
master stroke in preserving the fiber in
vegetation, especially in mountain growing
trees, where it is found in greatest quantities.
Wood properly treated has wonderful durability,
and the necessity of preserving the integrity of
the sounding board of the piano needs no proof
at this time. But there are many types and
qualities of varnish, each for its own purpose. A
few vital hints in connection with the use of
varnish in the sounding board work should be
sufficient.
Keep unused portions of varnish away from the
air as much as possible. Keep brushes perfectly

13. clean, and brush out the varnish rapidly from
spare dipping as thinly as can be smoothly done
in each coat to be used. Plenty of time must be
allowed between coats. This will give the
finished product an elasticity of surface it
cannot have in any other way, will insure against
cracking and consequently will prove impervious
to moisture.
Granting that the ideal repair job can be done
best in a shop equipped with every convenience,
still probably two-thirds of piano owners are
living too nearly to the limit of their allowances
(?) ever to afford, or to feel they can afford, to
send their pianos to shops. Of those who might
afford to do so a great many will decide against
it. An efficient, sure and speedy method for the
accommodation of this class, and especially
valuable to the independent man who has no
shop, will be shown later.
Before launching upon this subject, I will say
that I have found boards come unglued again in
pianos that have been sent back to the factories
to have their sounding boards repaired, probably
because of the fact that conditions are
overwhelming against the durability of the
methods employed. For the benefit of those who
may have a healthy fear of screws in the
soundboard, let me mention a piano which had
two hundred screws distributed over the entire
area of the board. Its tone was as full and clear
as any piano of similar quality of material,
design and workmanship I have seen. I have
actually found a few pianos in which, after the
sounding boards gave way and the repairs were
made, the tone carried better than when new.
Seemingly there is somewhat of a situation here
like to that found in some cars – they ride better
with a full load. Many have been the times that
my patrons, unbidden, have said: “Why, that
piano sounds better than it did when we bought
it, new,” and I refer to pianos whose sounding
boards I have repaired.
Now comes the time that I will describe my
method of making repairs, and the tools used.
Instalment 6
April 1926, pp. 510-513
When first considering the presentation of the
method which I have found best for the repairing
of piano sounding boards I thought of giving
mere outlines or details of the work itself. It
then occurred to me that a fair treatment of the
principles underlying the purpose and function
of the board would be of lasting value to men
whose opportunities had not hitherto placed
such knowledge in their possession, and the
editor of The Journal agreed with me that the
matter could be better handled in a series of
articles.
If any man would reap benefit from knowledge,
he must use it. To use it rightly he must fully
understanding it, and he must literally be full of
his subject. Thousands of sounding boards are
awaiting the expert attentions of skilled hands.
Mere discovery is the first step. Tactful breaking
of the news to the owner, and effective appeal
to his or her sense of need and pride in the
“excellence of condition of his or her own
property” – an idea that appeals to all minds, in
that whatever they have they want it to be all
right – is a leverage that can usually be
depended upon to bring a decision for the
repairs. Little need be said to the customer
about the method to be used if a right attitude
is assumed in regard to the need and the
certainty of an ideal condition of the finished
repairs. The cost is usually better based on
principle that it is the desire of the tuner to
deliver great value with fairness, but that on
account of the difficulties involved in the task
and the amount of work and time needed, the
job will cost so many dollars, which is less than
transportation of the piano to the factory and
return, to say nothing of the actual cost of the
repair if the piano were sent to the factory. The
method of persuasion will vary to suit the
individual and the occasion, of course, but I have
found the price named is usually a shock to the
customer, until a comparison of alternatives is
made, which leads to a decision in favor of the
repairs “at home” and “now”! On the other
hand, it would be obviously false tactics to
persuade a generous, wealthy, broad-minded
patron to have his repair made the “cheaper
way.” Efficiency, and not economy, is his chief
consideration.

14. Nothing can take the place of the ability to
present a proposition convincingly, appealingly,
persuasively and with no appearance of concern
except to serve the patron in the finest possible
way. Such bluntness as, “Madam, your piano’s
got a busted sounding board. I’ll have to charge
you ____ dollars for fixing it,” rightly brings the
reply, “Mercy!” or some such ejaculation, and a
decision to “see about it.” In brief, an
explanation of the purpose, importance, and the
function of the sounding board, together with an
appeal for the opportunity to restore the tone to
the piano, with a quiet assertion that tuning
without this work is wasted, worthless, and a
risk to “my reputation which I cannot afford,”
will in most cases bring the authorization to “put
it in shape.”
No two repair jobs in sounding boards are
exactly alike. For this reason a man must
exercise judgment. The facts concerning
elasticity, density, intensity and velocity, which
have been presented in this series, require that
repairs be made in a manner to affect these
qualities as little as possible, which is best done
as herein outlined. Variations from this set of
requirements are apt to produce “rumbles,”
“distorted amplifications,” unbalanced designs
in the travels of waves and their reflections
manifested in queer “raspy,” pinched or
dwarfed tones, in certain parts of an instrument
that may be fair in other sections.
The tools needed are a brace and bits one-half
inch, three-eighths of an inch and on-quarter of
an inch; three screw drivers, one large, one
small and one with a long bit; if possible, two
Yankee drills one a two-handed operated
ratchet, or crank for heavier work, the other of
the spring-ratchet type for light or delicate
work, enabling one to leave the different sized
ready for instant use in the different depths, as
drilled; prying tools, either hickory or oak slats
pared thin enough to be convenient or tire tools
made of discarded broken car springs; a thin
spatula, or pliable knife, for determining all
loose places, also for use as a glue knife; one
reamer, or combination tool including reamer,
and other bits of equipment; one gross of half-
inch No. 7 or No. 6 round headed screws in blued
steel, one gross of three-quarter inch No. 8 and
one gross of one inch No. 8 screws of the same
kind, with an assortment of longer and larger
screws for emergencies; about fifty wedges of
either hickory or oak, from ten to fourteen
inches long, tapered from less than one-half inch
thick at the small end to one inch at the larger
end, not over three-quarters of an inch wide;
and other tuning and repair kit paraphernalia.
For ease in repairing the top of the board a piece
of strap steel, prepared as in diagram C, enables
one to draw the parts together without
bothering the tension of the strings.
Procedure: wash the board thoroughly. Find
every loosened place, and mark each end. Mark
a spot for the screw in the exact center of the
central rib that is loose. Group the locations for
the screws in the rest of the board as
symmetrically as possible, that is, put about the
same weight of screws on each side of the
center. It would take a great deal of writing to
explain fully why I advocate this, but the truth
stated in earlier articles should make it seem
advisable to arrange the screws carefully, to
respect the balance in the periods of vibration.
Referring to diagrams A and B the manner in
which the screws are to be used will be seen.
The wedges and prying tools are always to be
used in bringing the parts together before the
screws are inserted. In the drawings will be
found details worth noting.
One caution: when a cupped place is found in
the board never pry it back to the rib. Brace it
on the strung side of the board and then pry
(avoiding any strain shear-wise) the rib back to
the board. The way I have found most effective
to get the glue well under the ribs is not to force
the knife completely under, but to slide the
edge of the knife repeatedly through the glue to
be worked under. A small portion can be caught
with each stroke and worked till the oozing fluid
appears on the opposite side of the rib. This
avoids bruising the wood of the board or
enlarging separated parts.
If the rib and board be forced tightly together,
a hole need not be more than started into the
board with a drill of only one-sixteenth inch size,
Caution must always be exercised never to
overturn the screw. When properly settled into
position a small screw may possess wonderful

15. power to hold; if overturned ever so little, it is
worse than useless.
To prevent drilling beyond desired depths, an
assortment of spools cut to fit on the drill bits
and to engage the chuck at the instant proper
depth is reached will save time in
measurements, and will insure uniform
accuracy.
It will sometimes be found necessary to place a
screw back of a stanchion, which can be done
through a hole made by a brace and a three-
fourths inch bit. This will call for a “screw
holder,” and one long bit of the size 11/64,
which can be made by the tuner. A pedal prop,
a file, and a bit of patience turn the trick. The
threaded end is to be filed for cutting, and the
shoulder end for chuck. Usually, however, it is
found possible to insert screws from the
opposite side of the board, that is, on the strung
side, back of the stanchions, in which case the
hole in the board is to be as large as the screw,
and the hole in the rib very small. Flat-headed
screws and sound board buttons are always used
on the strung side.
The method described by Nels C. Boe, in the
January, 1926, issue of The Journal, page 402,
under the title Loose Ribs, is to be employed
wherever the loose places happen to be in the
clear of the plate.*
When cracks are no wider than about one-
sixteenth of an inch the most effective manner
of repair is to use the composition here
described:
Work thoroughly one part of glue into three
parts of yellow wood filler and into this mix
thoroughly two parts of high grade varnish, into
which all the powdered resin it will absorb has
been stirred. After blending this mixture until it
looks like pale, thick molasses if it is too thin to
stand easily upon a knife blade work in still more
of the powdered resin. The cracks should be
completely filled with this composition. It takes
almost three days for it to dry sufficiently to
stand up properly, and it is often necessary to
give a second application. It will take more than
one effort to prepare this composition as it
should be, since the exact consistency of both
the filler and the glue have so much to do with
the balance between the proportionate
amounts.
If there are strings in the center of the piano
that possess a jingle, say middle G, D and E with
accompanying black key tones, it is probably due
to a settled board, one in which too much of the
arch has been lost. In such pianos the tension
must be let off while the repairs are in progress,
and it is advisable to give the entire board, both
sides, a good bath in denatured alcohol while
some pressure is exerted from the rib side of the
sounding board. In all this work the judgment of
the mechanic is paramount. In any case the very
center of the board must not be lifted more than
one-half inch, with correspondingly less raising
outwardly from the center in every direction to
about one foot away from the center, while in
most pianos it will be found that three-eighths
of an inch lift, sustained by wedges upon the ribs
so placed as to permit the repairs described
herein, will prove sufficient. There are pianos
that will not need more than a good one-eighth
of an inch lift. The surface of the varnish of the
board is presumably very porous – I have never
found a sunken board in which this was not the
case – and for this reason the alcohol will
penetrate within, dissolving the shellac
originally used, as well as the natural content of
resin. This will permit the necessary molecular
readjustment, and favor permanence of the new
form, if proper care is exercised in the coats of
shellac and varnish following the repairs. The
strings can be tied near their middle in groups of
six, nine or twelve, without unhitching them, to
make room to reach the board easily. There is
little hope for the board that was made with too
slight an arch, as is sometimes the case. I have
a remedy, but I hesitate to pass it on.
With the purpose of the parts clearly in mind,
and the nature of the sounding board so well
understood, I believe that matters can be
trusted to the ingenuity of the individual.
The greatest difficulty that faces the tuning
profession is the attitude of the piano owner.
Each man must solve his own problem of selling
his service. Perhaps the patron’s attitude will be
found to yield greatly to intelligent and
intelligible appeals to his pride, sense and
desire. If there happen to be tuners who never

16. fail to bring their prospects to the decision to
have each and every item of repair made just as
the tuners deem best at whatever price is asked,
they either have a better set of patrons than I
have found, or are much higher-powered
salesmen than I happen to be.
Within the function of amplification exists the
finest reason for the most frequent tunings of
pianos. This I hope to be able to give in another
article sometime.
THE END.
*(Here is what Mr. Boe had to say in answer to a
query):
If the ribs are loose only in places there should
be no difficulty in drawing the board and ribs
together, and nearly if not entirely restoring the
original “belly,” or at least the belly the board
had before it was separated from the ribs. The
board should be taken out only as a last resort,
when everything else has been tried and has
failed to bring about satisfactory results,
because such a job involves problems entirely
too big and too complicated, except for the best
equipped repair shops.
In drawing the ribs and board together hot glue
is preferable, and screws of the proper length
and sounding board buttons are absolutely
essential.
First clean off all the old glue as well as you
possibly can, select screws of the proper length
and size, that is, screws that are long enough to
go through the buttons and board and well into
the ribs but not through them. Also see that the
holes drilled for the screws are of the right
dimensions so as not to split the ribs or the
buttons.
When everything is ready apply the glue, not too
sparingly, to the ribs and the board, place the
buttons on the front side of the board, insert the
screws through the buttons and draw together.
Use as many screws and buttons as are found
necessary.