THE IRON FRAME OF THE PIANOFORTE.
In the historical portion of the present work, ample reference has
been made to the genesis and early development of metallic framing in
the construction of pianofortes. We took occasion to point out that
the independent development of the American pianoforte is intimately
connected with the rise and improvement of the system. It is a matter
of no little pride to recall that in the universal recognition of
the value of metallic adjuncts to the framing devices of the modern
pianoforte, the Americans, as became their traditions, blazed the
trail. It is unnecessary to repeat the observations that were made in
Chapter II as to the controversies that have raged over the question
of priority of invention. It is sufficient to refer the reader back
to that portion of the present work where these questions have been
treated in a sufficiently copious manner.
We may therefore proceed directly to the task of investigating the
nature of the universal metallic framing that has been demonstrated to
be so essential in modern constructional systems. Following the plan
that we have adopted throughout, we shall first consider the nature and
application of this kind of framing to the grand pianoforte.
As to the form, then, of the iron framing, its weight and size. Ever
since the first grand pianoforte was produced with an iron plate cast
in one piece, designers have been busy with attempts to improve upon
the original invention. They have met with but moderate success. There
have been multifarious changes in the details of bracing and of fitting
the plate to the case, but the general form of the original design
remains the same. It may be described in general terms as follows:
A plate of iron cast in one piece, which follows the outline of the
instrument and is so arranged that it may be secured to the case and
to the wooden framing that underlies and knits together the latter and
the sound-board. A gap is left in this plate at the point where the
hammers strike the strings, and the resultant weakness is overcome
by a system of bracing by means of resistance bars, also of iron and
cast in the same piece with the main body. At its front end, nearest
to the key-board, the plate is extended so as to cover the wrest-plank
in which are driven the tuning-pins; and at the end remote from the
key-board it is provided with a number of hitch-pins, to which are
secured the waste ends of the strings. This plate, further, is so
arranged that the sound-board is not covered by it except at the edges,
and at the place where the bass bridge is constructed another gap is
left in its surface.
[Illustration: JONAS CHICKERING’S FULL SOLID CAST GRAND METAL PLATE.]
The above general description comprehends in bare outline the
essential features of the iron framing. There are, of course, many
variations of detail, and in seeking for the best methods of designing
this important part of the pianoforte we shall have occasion to examine
the greater number of these with some care.
[Illustration: SKETCH OF IRON PLATE FOR CONCERT GRAND, SHOWING GENERAL
ARRANGEMENT OF BRACES, BELLY-BRIDGES AND SYSTEM OF BOLTS FOR FASTENING
TO CASE.
A--B. Hammer line.
1. Body of plate.
2. Bass bridge.
3. Continuous treble bridge.
4. Agraffes.
5. Capo d’astro bar.
Plate is cast in one piece and scale is overstrung.
]
Of the various differences of detail that designers have effected
in the construction of iron framing, one of the most important is
presented in the so-called “cupola” style of construction. In this
form the surface of the plate is raised at the edges of the case in
such a manner as to give the general outline of a cupola or semi-dome.
The result of this method is to increase the resonance of the framing
and, at the same time, greatly to enhance the tensile strength of the
whole construction. The “cupola” style was the subject of a patent by
Steinway & Sons of New York some years ago, but has been extensively
copied since that time. The same celebrated house was the originator of
another variation upon the classic manner of plate building. Instead
of arranging the strings in the usual manner, a fan-like disposition
was adopted, with the result of distributing the strain more evenly
throughout the entire surface and thus improving the tensile qualities
of the whole plate. All these methods of construction, however, have
failed to avoid that breaking up of the scale which is made necessary
by the interposition, between the string groups, of bars and bracings.
It has appeared impossible to obtain the requisite resisting power
without the assistance of a number of heavy iron braces cast into the
plate and designed to increase the tensile strength, which is weakened
by the gap at the striking points of the hammers.
[Illustration: ARRANGEMENT OF IRON PLATE, BRACES AND SCALE OF PARLOR
SIZE GRAND PIANOFORTE.]
There has, however, appeared an invention which would seem to overcome,
in an effective manner, the objections to a multiplication of bracings.
The inventor is a member of the celebrated house of Broadwood, and
his device is called the “Barless” or “open scale” grand pianoforte.
By this invention the barred iron frame is replaced by a plate of
mild steel, which is entirely free from bracings, is constructed
with a continuous turned-up flange and is bolted in the usual manner
into the bottom framing. This flange provides the necessary tensile
strength and apparently sustains the tension of the strings in a
perfectly satisfactory manner. The advantages presented by a method
of construction that avoids the breaking up of the string groups into
three or four divisions are obvious and need not be explained in detail.
It may be stated, however, that the principal and conspicuous advantage
presented by this method of construction is found in the fact that the
absence of the usual barring and bracing tends to subdue the metallic
and tinkling quality of tone that is so often found to be induced
by the presence of heavy masses of cast iron. At the same time, the
material employed is so much more elastic than iron that there is no
perceptible loss of resonance, nor is the tensile strength lessened
to any appreciable degree. No one who has tested the pianofortes thus
constructed has failed to be delighted with the singularly beautiful
tone-quality and remarkable evenness that is shown throughout the whole
compass. It is indeed a most difficult task to overcome the tendency to
production of unduly prominent dissonant partials in those parts of the
scale where the bracing is especially heavy, particularly in the lower
portions, and consequently we must regard with admiration so successful
an attempt to do away with these difficulties by removing their cause.
It may be noted at this point that the eminent firm referred to before
as having introduced the “cupola” form of construction, also employ
steel in the making of their metal frames, and it seems curious that
this example has not been more generally followed.
The two types thus described are the most radical exceptions to
the common style of metal framing. It is a matter of regret that
manufacturers in general have been content to follow so closely in the
footsteps of the pioneers, and have not experimented more energetically
with a view to effecting other improvements in the accepted methods.
The problem of sustaining the necessary tensions would undoubtedly
be simplified by the adoption, at least in part, of the ideas of the
eminent firms who have already been mentioned.
In order thoroughly to understand the actual advantages and
disadvantages of the various styles of framing that have been
described, we must consider how great are the tensions that they are
compelled to bear. A concert grand pianoforte of a standard American
make is so constructed that it bears a total strain, when tuned at
concert pitch, of not less than 30 tons. The requirements of increased
tone and the weight and bulk of strings tend constantly to augment
rather than to decrease these tremendous strains, and at the same time
more and more to induce the production of those dissonant partials that
have such a maleficent influence upon tone-quality. Obviously, then,
if we are to satisfy the popular demand for greater volume, and at the
same time to maintain the highest standards of quality, we must seek
for some method that will obviate the employment of yet heavier masses
of cast iron and at the same time preserve the necessary strength and
rigidity. The methods of construction that have been noticed at some
length above seem to present manifold advantages over the older styles.
Steel has greater tensile strength than iron, and consequently a
smaller bulk of it is required. Again, its elasticity is higher and the
vibrations impressed upon it traverse its surface with greater facility
and in a shorter period of time. Whether, therefore, we prefer the
barless or the cupola style of construction, we must recognize the fact
that steel is a better material than iron in any form.
Foremost among the requirements of a successful framing system are
that it shall sustain its burden with such rigidity that the strings
shall stand in tune and the wooden case of the instrument shall not
be twisted out of shape. Even if the material be the best possible, a
faulty method of securing the metal frame to the case will not only
prevent the consummation of these desires, but will tend to weaken the
sound-board and hasten its splitting. It is essential, in fact, that
the board should be relieved of strain, and great care must therefore
be exercised in fitting the framing. The approved method is as follows:
The framing is connected with the system of wooden posts that extend
below the sound-board and bind together the sides of the case. The
latter connection is made by means of long bolts that extend through
the bracings of the frame and are sunk into the posts at convenient
places. The sound-board is secured to the sides of the case by means
of its ribs, which are continued beyond its edges and pocketed into
the sides and the posts, and also by being glued to the bottom surface
of the case and to the system of posts. Lastly, the frame is connected
both with the board and the posts, by a series of heavy screws that
pass through the board and into the posts at regular intervals along
its outer edges.
This method of securing the frame and sound-board to the case ensures
that the former shall be incorporated within the body of the instrument
as rigidly as is possible, and that the latter shall have the fullest
protection against those twisting strains that the metal frame alone
ought to bear.
With such a method as has been described we can find no great fault.
It should be noted, however, that in the barless or open scale
construction the bolts that were described as passing through the
braces into the posts below are omitted, and the whole frame is
supported within the case by a series of bolts driven through the
turned-up steel flange at equal intervals in its surface.
Having thus considered the forms of framing that are employed by
various makers we may turn our attention to the matter of suspending
the strings across the frame and over the sound-board. The upward
stroke of the hammer of the grand pianoforte tends to drive the string
away from its bridge and thus to lessen the energy with which the
vibrations imparted to the string are impressed upon the latter. We
may note that all makers are agreed in giving to the strings of a
grand pianoforte an upward thrust or “bearing” in order that the blow
of the hammer may throw the strings against the upper surface of the
bearing-bridge instead of away from it. There are two devices that are
generally employed for this purpose. They are known as the “agraffe”
and the “capo d’astro bar.”
The first of these was the invention of the celebrated Erard of Paris.
It consists of a brass stud screwed into the iron framing (or into the
wrest-plank where the plate does not extend over the latter), at the
beginning of the speaking length of each string or group of strings.
This stud is bored with the required number of holes--one for each
string in the group. These holes are bored at such an angle that the
ends nearest to the tuning-pins are higher than the other ends, while
the pins are placed at a higher elevation than the agraffes. In this
manner the string is given an upward thrust as it proceeds toward the
tuning-pin, and the blows of the hammer force it against the upper
surface of the agraffe, which, being solid, conveys the impressed
vibrations through the medium of its own surface to the framing.
The “capo d’astro bar” performs the same functions in a slightly
different manner. It is practically a continuous “agraffe,” and
consists of a metal bar which is cast into the metal frame at the
beginning of the speaking length of the strings. It is fitted,
according to the best practice, with an under edge of tool steel, and
the strings are caused to pass underneath it on their way toward the
tuning-pins, which are higher than the bar, as before. The up-bearing
is thus imparted to the strings in a manner similar to that which is
followed in the case of the agraffes.
As to the advantages of the two systems, it may be said that the “capo
d’astro” undoubtedly overcomes those objections to agraffes which are
based upon their tendency to pull out from their places. It provides
an absolutely rigid resistance, and is therefore stronger and more
reliable.
On the other hand, however, the mass of metal employed is considerably
greater than in the “agraffe” method, and the resultant influences upon
tone-quality are clearly disadvantageous.
Further, the work of tuning is rendered more difficult by reason of
the fact that the strings cannot so readily and correctly be pulled
through the space intervening between the bar and the tuning-pin.
It is debatable whether the greater rigidity and resonance offered
by the “capo d’astro” method are not too dearly bought at the cost
of inconvenience in tuning and deterioration of tone-quality. It is
noteworthy that most manufacturers confine the “capo d’astro” bar to
the high treble register of their instruments, where brilliancy and a
somewhat metallic quality of tone are a desideratum.
The iron framing of an upright piano follows the same general lines of
construction as have already been noted in the previous discussion of
the grand. The functions of the frame are precisely the same and its
construction differs outwardly but little. There are, however, certain
divergencies from the grand forms that must be noted carefully. For
example, it will be remembered that the form of the upright pianoforte
is such that the framing has no direct and positive connection with the
outside case. It is thus impracticable to consider the sides of the
iron plate as homogeneous with the sides of the case, nor is it possible
to give to it that consistency of form that, in the grand, results from
the shaping of the plate to correspond with the curved outline of the
case. This, however, is no reason why the upright iron plate should not
be as strong and secure as that of the grand.
[Illustration: IRON PLATE FOR UPRIGHT PIANOFORTE FITTED WITH CAPO
D’ASTRO BAR.]
Among the various differences of detail that we observe to exist
between these two forms of plate is the device adopted to secure
the bearing and rigidity of the strings at their upper end deserves
notice. The practice is entirely different in this respect as regards
the upright, and we are therefore introduced to a new feature: the
“pressure bar.” This device has superseded both the old-fashioned
pinned bearing bridge and the later agraffe forms. It consists,
essentially, of a bar of heavy metal that is screwed into the
wrest-plank through the metal plate and is placed so that the strings
pass under it on the way to the tuning pins. In fact it occupies the
same position as do the agraffes or capo d’astro bar on the grand. Its
function is also similar; namely, accurately to delimit the speaking
lengths of the strings at the upper end and to assist in the formation
of a thrust or bearing whereby the latter may more advantageously be
secured.
[Illustration: IRON PLATE FOR UPRIGHT PIANOFORTE WITH AGRAFFES (MEHLIN
PATENTS).]
This form of building the bearing bridge possesses important
advantages. It does not require to be cast into the plate, nor is it
weakened, as in the agraffe system, by being broken up into a large
number of units. Moreover, the bearing for the strings is formed much
more smoothly and easily between the pressure bar and its attendant
ribs on the plate than is possible when either the agraffes or the capo
d’astro bar are used. This is an important point, for such construction
tends to make the task of tuning much more rapid and correct.
There are, however, several points to be considered in the designing
of pressure bars. As a general thing, it is impracticable to apply this
form to the bass strings on account of the fact that the overstringing
requires of them a slanting direction. On this account the pressure bar
cannot be made properly to maintain the obliquely-running strings in
their respective places. It is therefore usual to build the bass bridge
after the old pinned type and thus to secure the bass strings by much
the same device as is employed in the belly bridges.
As far as the designing of pressure bars is concerned, it will be found
that care should be exercised in arranging the space that the bar must
occupy and its position with regard to the scale ribs that are placed
on each side of it and that support the strings before and after their
passage under it. In general it may be said that the pressure bar must
be screwed in such a position that its lower curved surface is lower
than the upper surfaces of the scale ribs by about one-half of the
height of the latter. It must also describe a curve that corresponds
to the dip or angle of the scale and must be secured by enough screws
(one between each three string-groups is usual), to ensure that the
pull of the strings will have no injurious effect upon its rigidity.
It is also essential that the curve into which the string is bent
during its passage under the pressure-bar and over the scale-ribs be
not too deep or sudden. The bearing surface of the bar should be gently
rounded until very near its middle point where the string exercises its
greatest pulling strain. Here the surface must be curved a little more
sharply.
The iron plate of the upright is the chief supporter of the strains
imposed upon the structure by the strings. It is necessary, as in the
grand, that it should be built so as to have absolute rigidity under
these strains, and that it should be always capable of withstanding
any others that may by any chance be imposed upon it. Remembering
this, what shall we say of the designs that we sometimes see where
the iron is cut and shaved away at every possible point in order to
save a few pounds of weight? There are pianofortes in existence where
the iron framing is so much cut down that the treble can never be
depended upon to stay in tune for a reasonable length of time, and
where the unevenness of the distribution of metal throughout the body
of the frame has caused a warping of the whole instrument out of its
proper shape. All this is unnecessary, but it will continue so long as
manufacturers are willing to effect small savings at the expense of the
future reliability of their product.
It is certainly much better to have the plate of the upright
pianoforte so arranged that the total volume of iron, if it is to be
decreased, may have this process applied evenly and all through. The
most correct design would consider a moderately heavy plate of iron, or
better, of steel. This plate would be so arranged that the hitch-pin
plate (the portion which carries the hitch-pins) covers the entire
surface of the instrument at its bottom end and is bolted into the back
with as many and as heavy bolts as are employed at the other end. The
upper portion of the proposed plate need not extend over the surface
of the wrest-plank, for such a construction can add little to the
resisting power of the frame, while it inevitably tends, for reasons
that have already been described, to the production of dissonant
partials and the consequent emission of a metallic tone. If it is
desirable, for any reason, to cut down the weight of a frame, it can
better be done at the upper end than at the lower, where diminution of
the resisting power of the frame is most severely felt.
We may, then, contemplate a form of iron frame which covers that
portion of the back-framing whereon the edges of the sound-board
are glued, and that is not continued up and over the wrest-plank.
It will be cut away in the centre, as in the grand, and will thus
expose a large part of the sound-board to view. It will be provided
with a certain number of bracings for the purpose of taking up the
strains that are imposed upon the structure at the points of greatest
resistance, such as those where the over-stringing begins and ends, and
those around the middle registers of the scale. There must not be more
of these bracings, however, than is necessary, as it is very important
that the scale should be broken up into the least possible number
of divisions. The bracings will be so designed that no one of them
interferes with the true curve of the belly-bridge. The whole structure
will be solidly bolted into the back-framing through the sound-board by
a series of long and heavy screws and bolts that will be inserted at
frequent intervals along the edges.
We cannot conclude this survey of plate-construction without taking
note of a property that is common to all cast-iron structures. We refer
to shrinkage. The calculations of the designer, no matter how carefully
worked out, must take into consideration the fact that cast-iron
shrinks largely in the cooling. It must be noted that the design for
the iron plate is the chief portion of the work of scale draughting.
As will be explained later on, this work is first done on paper and
then transferred to a wooden pattern. From this pattern the casting is
made. After the first casting is thus completed it is taken in hand
by the designer, who marks and punches it for the boring and pinning
and corrects it where necessary. The corrected casting is then used as
a model for the future plates that are to be turned out for the same
scale. But these also shrink; so that we are compelled to take into
account both shrinkages, and allow for each. Fortunately, however,
there is no difficulty in arranging this.
The method is as follows: After the string-lengths have been calculated
and the size of the iron plate thus determined, a complete drawing is
made, showing the exact dimensions, shape, and other features of the
proposed plate. This is to be used as the guide for the wooden templet.
But this difference exists between the two paper drawings; namely,
that the second is multiplied as to every dimension of the plate by a
quantity that represents the amount of shrinkage that is known to occur
in the two castings.
The average shrinkage of cast-iron in the form of pianoforte plates is
estimated at about one per cent. Consequently to account for the double
shrinkage it becomes necessary to multiply by the square of 101/100;
that is approximately 51/50.
A great deal of trouble will be avoided if the shrinkage is carefully
worked out in this manner. Every dimension of the plate is affected,
and the greatest care must be taken to ensure that the corrected
calculations are accurate. Only thus will it be possible for the ideas
of the designer to be brought out in the completed instrument as he
expects to see them.
CHAPTER XI.
THE MECHANISM OF PERCUSSION.
The pianoforte hammer is perhaps the most striking of the many and
various features of that instrument. Although it is a comparatively
simple device, its historical and musical interest is supreme. For
while the strings, the framing, and even the action that we see in
the instruments of today are but the modern developments of their
clavichord and harpsichord ancestors, the hammer, on the contrary, is
the one revolutionary device that, at a single step, separated the
pianoforte from all other stringed instruments and endowed it with its
own peculiar and powerful attributes.
It was the hammer, in fact, that made the pianoforte. As soon as it was
fitted into a harpsichord, the pianoforte was born, and no refinement
of stringing or framing could have effected the fundamental nature
of key-board instruments in the same manner. For we must recognize
the fact, sometimes overlooked, that the pianoforte is essentially an
instrument of percussion. It is necessary that there be a more or less
violent blow from the hammer to excite the sound-producing vibrations
of the strings. The tone of the instrument, under the most favorable
circumstances, cannot fail to partake of the character peculiar to
sounds produced in this manner. The importance of the hammer as a
tone-producer cannot, then, be underestimated. It stands upon a plane
of importance equal to that occupied by the scale-designing, the
stringing and the resonance apparatus. We are therefore justified in
devoting space to consideration of the construction of this essential
feature.
We cannot say with absolute surety what was the nature of the
material with which the hammers of Cristofori’s original invention
were covered. But we may presume that it was leather. We know that the
hammers were exceedingly small and apparently all of the same size.
Neither Silbermann nor Zumpe can be said to have perfected any special
improvements in the form of hammer construction, and we find that the
revolutionary genius, John Broadwood the First, and also Sebastian
Erard, were the pioneers in the work of adapting the hammers to the
more strenuous styles of playing that the improved touch mechanism
invented by them permitted and encouraged.
Broadwood, who first perceived the necessity of adopting a
scientifically correct striking point, likewise began to fit his
pianofortes with hammers graduated in size, and under him the
leather-covered hammer arrived at its full development.
But leather as a covering material soon began to be decried. It was
discovered that the kind of tone demanded by the rising pianoforte
masters could not be obtained from such material. After much experiment
on the part of pianoforte makers, the German-Frenchman, Pape, of Paris,
tried the use of felt. His success was immediate and conspicuous, and
it was discovered that not only did this kind of covering produce
finer tone quality, but there was little difficulty in regulating
that quality through the hammers within certain well-defined limits.
Nevertheless, we find square pianofortes to-day in which the felt
covering upon the higher hammers is overlaid with strips of buckskin.
This practice, however, represented the last dying struggles of the
leather-covered hammer, and now we use it no longer.
It is true that the use of felt is not unattended with conspicuous
disadvantages. It wears out rapidly, and unless constantly kept in good
condition by use of the felt-needles, the iron, and the sand-paper
file, soon comes to produce a harsh and unpleasant tone-quality. This
defect arises from the fact that as usually constructed, the continual
pounding of the hammer head upon the strings causes the felt on the
crown of the hammer head to become tightly packed and compressed,
and the shaping of the head to be lost. As will be explained later,
this change in the manner in which the head is originally made up
causes a modification in the nature of the vibrations set up in the
strings, and, as we have already learned, this change in the nature
of the produced excitement is the cause of unpleasant tone-quality.
Nevertheless, and in spite of these real disadvantages, the use of
felt as a covering material for pianoforte hammers is now universal.
Nor does it seem at present that we are very likely to find a superior
substitute. As we shall shortly see, however, a simple change in the
manner of securing the felt to the wooden foundation of the hammer-head
may be depended upon to add largely to the durability and efficiency
of the whole structure, both as a tone-producing medium and as a
mechanical device.
As will be surmised by the reader, early covering of pianoforte hammers
with felt was a tedious operation. The material was cut up separately
for each hammer, and glued on to the wooden head by hand. But this
method suffered under the grave disadvantage of affording no correct
guide to the true thicknesses and no means other than furnished by
hand-cutting, of graduating these thicknesses with exact evenness.
It remained for an American (or Americanized German) inventor to
devise a machine that should glue up and finish an entire set of
hammers from one continuous sheet of felt, of which the thickness was
graduated in the making and which could be relied upon to contain
the correct amount of felt, of any desired total weight, the whole
graduated with great evenness. Not merely was this so, but the methods
of manufacturing felt for other special purposes connected with the
manufacture of pianofortes has been entirely revolutionized, so that
today we have dampers, punchings, and many other parts of the mechanism
of pianofortes successfully manufactured out of various kinds of felt,
which vary greatly in consistency, thickness, and other properties.
To return, however, to the special case of hammer-felt. We find that
the original methods of working together the layers of carded wool
has been much improved, chiefly through the efforts of the inventor
mentioned above. It is now a matter of slight difficulty to turn out
sheets of felt for the making of piano hammers that shall have any
desired weight, size and graduation of thickness.
The weight of the sheets of felt varies largely according to the nature
of the hammers that are to be produced. Thus it is customary, as may be
guessed, to provide full-size concert grands with hammers of greater
thickness, while the smaller styles of instrument have progressively
smaller hammers. The actual weights vary according to the caprice or
calculation of manufacturers and designers. An average weight of felt
for hammers suitable to be placed in a nine-foot concert grand is from
16 to 18 lbs. per sheet. This does not include the “underfelt,” which
is glued directly to the wooden head of the hammer and is used to give
greater resiliency to the lower hammers. It is generally omitted at the
higher treble end.
Upright pianofortes frequently are hammered with felt weighing not
more than 8 lbs. to the sheet, but this seems to be too light for
really efficient results. 10 lbs. is quite light enough in most cases.
As has already been indicated, the foundation of the hammer is a wooden
molding. Over this is glued, in the machine, a strip of “underfelt,”
which is long enough to cover about five and a half or six octaves of
hammers, counting from the bass end upwards. The main felting is then
laid over this, the thickest end being at the lowest bass. By means of
the machines, now so generally used, it is possible to glue the entire
underfelt and also the topäfelt, in one piece. The moldings are then
separated and the operation is complete. It is customary to insert a
small piece of wire, doubled over in a loop, through each hammer, in
order to ensure further strength to the fastening.
As may well be imagined, the details of manufacture, of the quality of
the felting, and of the dimensions of the completed hammers, require
much care in their execution. Long practice, study, and experience
have combined to render the specialists, who devote themselves to the
preparation of hammers and hammer-felt, most excellently fitted to
place upon the market the very finest productions of this kind.
There have been attempts made at various times to provide a hammer
head, and a method of felting it, that would obviate the somewhat rapid
deterioration caused by the pounding of the glued and compressed felt
against the stiff steel wire strings. The felt, which requires to be
compressed before it is glued on to the wooden molding, rapidly becomes
altogether too hard. Moreover, the fastening of the felt to the molding
is by no means really permanent. It has been suggested that the felt
might properly be contained within a wooden shell which would extend
as far along the sides of the felt as the wooden molding now reaches
within it. The compressed sheet of felt would be forced into this shell
and fastened therein so that it would always be protected by an outer
wooden covering. Thus, not only would the fastening of the felt to the
wood be reduced more secure, but the pounding upon the strings would
not so rapidly assure the undue hardening of the felt. For there would
not be the hard wooden base between which the strings and the felt is
continually subjected to compression. The idea is good and undoubtedly
will yet be recognized.
Details of the adjustment of the hammers to the rest of the action
and of the preparation of them by the tone-regulator, for the better
production of good and even tone, will be dealt with in the chapters
upon action-and tone-regulating.
CHAPTER XII.
THE TOUCH MECHANISM.
As the hammer-idea evolved itself in the mind of Cristofori and
the other experimenters who were contemporaneously bending their
efforts towards the improvement of the dynamic possibilities of
keyed instruments, we may be certain that much perplexity was caused
them by the problem of providing some mechanism that should form the
connecting link between the hammer and the key. We may understand
how the ingenious Italian must have labored, with the picture of the
dulcimer and its player continually in his mind, to obtain an efficient
mechanical substitute for the uncertain stroke of the hand operated
dulcimer-hammer, as well as the dynamically incapable harpsichord jack
and quill. It is surprising to note, indeed, how early the present
ruling principles of action-mechanism were elaborated by these pioneer
workers. Cristofori, as we have already mentioned, obtained, ere he
died, a complete check to the rebound of the hammer and a form of
escapement that may be seen unaltered in essentials in surviving square
pianofortes of the “English action” variety. We may further reflect
that the invention of Backers, as improved by John Broadwood the
First, remains today the approved mechanism of many English and other
European grands. Not only is this so, but until the general adoption
of the Steinway overstrung model, there existed German makers who were
content to fit their moderate priced grands with a slightly modified
form of the Viennese action invented by that remarkable woman Nanette
Stein, afterwards Madame Streicher, the conspicuous feature of which
was the mobility of the hammer-butt and the stationary condition of
the jack. The fact that these early mechanisms remained satisfactory
to performers until recent years is the best proof of the thorough and
sure mechanical basis upon which they were designed.
It is not necessary to go into elaborate detail in describing these
early actions. Reference to the accompanying cuts will be sufficient
to lay bare their actuating principles. We may, however, observe that
the radical difference of touch between the Viennese (Streicher) models
and those of Broadwood (known as the English grand action) continued
to be a source of annoyance to performers until the increasing
technical demands of the modern virtuoso school and the improvements
in wire-drawing and iron casting made inevitable the supersession of
the very light Streicher action by the heavier, more durable and more
efficient Broadwood English model, which continued in favor until
within recent years.
[Illustration: CRISTOFORI’S ACTION IN ITS FINAL FORM.
1. Key.
2. Jack.
3. Jack-operating spring.
4. Cushion limiting rebound of jack.
5. Under-hammer.
6. Hammer-butt.
7. Hinge of hammer-butt.
8. Hammer-shank.
9. Hammer head.
10. Check.
11. Damper-lifter.
12. Damper-head.
13. Action-beam.
14. Wrest-plank.
15. Tuning pins.
16. Bearing-bridge.
17. String.
]
[Illustration: ACTION BY ANDREAS AND NANETTE (STEIN), STREICHER
VIENNESE ESCAPEMENT (1794).
1. Key.
2. Jack.
3. Jack-operating spring.
4. Cushion limiting rebound of jack.
5. Button and screw regulating escapement of hammer.
6. Hammer-butt and operating face.
7. Hammer-butt pivot.
8. Hammer-shank.
9. Hammer-head.
10. Check.
11. Damper-lifter.
12. Damper-head.
13. Action-rails.
]
[Illustration: ENGLISH DIRECT LEVER GRAND ACTION, DEVELOPED BY
BROADWOOD FROM BACKERS (1884).
1. Key.
2. Jack.
3. Jack operating spring.
4. Rail and cushion limiting travel of jack.
5. Button and screw regulating escapement of hammer.
6. Hammer-butt with operating notch.
7. Hammer-butt flange.
8. Hammer-shank.
9. Hammer-head.
10. Check.
13. Action-rails.
]
[Illustration: DOUBLE REPETITION ACTION OF SEBASTIAN ERARD AS USED BY
S. & P. ERARD, PARIS.
1. Key.
2. Wippen.
3. Jack.
4. Escapement lever.
5. Hammer-shank.
6. Roller.
7. Hammer-head.
8. Jack regulating button.
9. Regulating button to limit rise of escapement lever.
10. Hammer-butt.
11. Check.
12. Felt cushion to engage with check.
13. Sticker connecting key and wippen.
14. Action-rails.
15. Damper-head.
16. Damper operating device.
17. Device to limit travel of jack.
18. String.
19. Spring (v-shaped) for escapement lever and jack.
]
Shortly before the general adoption of the Broadwood model, however,
there was brought forward a new type of grand action, which was
destined in its turn entirely to supersede the then favorite English
type. This was the invention of Sebastian Erard, of Paris, founder of
the still existing house of S. & P. Erard. His new action was termed
the “double repetition action,” and it fully deserves the name. By
the use of this device the leverage that exists between the hammer
and the key is so manipulated that the very slightest touch upon the
keys is sufficient to cause the hammer to deliver a blow. It will be
observed by reference to the cut that the Erard action differs very
largely from that of Broadwood. In the first place, we observe that
the hammer heel is no longer provided with a notch in which the jack
works, but that this heel is reduced to the smallest dimensions and
acts merely as a pivot. Upon the shank of the hammer is fastened a
felt-covered roller. The jack acts upon this roller. Between the jack
and the roller, however, we observe a long lever, one end of which has
a slot through which the jack passes, while the other end is pivoted
on to a rail projecting from the wippen. This is the “escapement” or
repetition lever, and forms the main improvement of Erard. It will
be observed that the repetition lever bears against the roller, and
indeed lifts it before the jack can come into engagement with it.
The jack, working through the slotted portion of the lever, is not
brought into play until the lever has raised the hammer a little way.
The long, double spring that acts both upon the lever and the jack
gives them their motions, and the result of the depression of the key
is that the repetition lever is always in engagement, and when the
angular key-motion is not sufficient to bring the jack into play, the
work will be done by aid of the lever. Furthermore, the lever operates
to maintain the hammer-shank in precisely the proper position for
striking, at all times, and without reference to the angular position
of the key.
It can easily be understood that such a vital change in action
mechanism did not become popular at once. Many pianists objected to
double escapement. Notable among these were Chopin and Kalkbrenner;
these two being the greatest pianists of their day in Paris. Chopin
preferred pianofortes fitted with the Broadwood action.
[Illustration: THE ERARD GRAND ACTION MODIFIED BY HERZ.
1. Key.
2. Wippen.
3. Jack.
4. Escapement lever.
5. Hammer-shank.
6. Hammer-butt notch.
7. Hammer-head.
8. Jack regulating button.
9. Regulating button to limit rise of escapement lever.
10. Hammer-butt.
11. Check.
12. Molded tail of hammer-head to engage with check.
13. Capstan-screw connecting key and wippen.
14. Action-rails.
15. Damper-head.
16. Damper-operating device.
17. Device to limit travel of jack.
18. Regulating device for escapement lever.
19. Springs (2) for escapement lever and jack.
20. String.
21. Flange.
]
Nevertheless, the merits of Erard’s invention continued to impress
themselves upon the musical world, although Pierre Erard, who had
patented his uncle’s invention in 1821, was obliged to obtain an
extension of the English patent in 1835, on the ground of the loss
occasioned in working it. It did not become generally adopted,
even after the expiration of the extended patent, until modified
and simplified by Henri Herz, the famous pianist and pianoforte
manufacturer. Then its merits, in the modified form, were so generally
recognized that it is now in use by Steinway, Chickering, Knabe and all
manufacturers of grand pianofortes in the United States; by Broadwood,
Collard & Collard, Brinsmead, and others in England; by Bechstein
& Bluthner in Germany, and by most French makers of eminence with
the sole exception of the house of Erard itself. This eminent firm
continues to employ the pure and original form of action as patented in
1821, with improvements only in details of workmanship and material.
Whatever we may say as to the general adoption of the Erard action
only after it had been considerably modified, we must not withhold
admiration from the Erards, whose genius and courage gave to us the
enduring double-escapement principle that has never yet been superseded.
The main features of the Herz-Erard mechanism may be seen at a glance.
The roller is replaced by the notch, once more restored to favor, and
the repetition lever is made more effective by being pivoted centrally
with two free ends, and by having means provided to limit its up and
down motion. Moreover, the wippen is shortened and made straight, the
single spring is replaced by two, and the damper is once more permitted
to fall down on the strings by its own weight without recourse to
artificial springs.
The Herz-Erard action has been taken up by American makers, but we find
that they have modified it again, after their own ideas. For example,
if we look at the accompanying cut showing a modern American grand
action of the highest class, we shall observe that the original roller
of Erard is restored, the damper mechanism simplified and additional
means of controlling the movements of the jack introduced. These two
latter improvements combine to make the present American grand action
most perfect, and the achievements of the specialist action makers must
ever command our respectful admiration.
The reader has now been able to take a comparatively complete survey
of the progress of invention in grand pianoforte action mechanism. We
shall therefore turn to a critical examination of the modern standard
grand action here illustrated, in order that the adjustment of it
within the instrument may be understood.
[Illustration: STANDARD MODERN AMERICAN GRAND ACTION.
1. Key.
2. Wippen.
3. Jack.
4. Escapement lever.
5. Hammer-shank.
6. Roller.
7. Hammer-head.
8. Jack-regulating button.
9. Regulating button to limit rise of escapement lever.
10. Hammer-butt.
11. Check.
12. Molded tail of hammer-head to engage with check.
13. Key-rocker and sticker connecting wippen and key.
14. Action-rails.
15. Damper-head.
16. Damper operating device.
17. Device to limit travel of jack.
18. Regulating device for escapement lever.
19. Separate springs for jack and escapement lever.
20. String.
21. Flanges.
]
It will be observed that the key (1) is supported upon a key-frame,
part of which is clearly shown in the drawing. This frame is provided
with a cloth strip at its rear end, also shown, and with a “balance
rail” upon which the key is pivoted by means of a pin. The position
of this balance rail must be such that the divisions of the key thus
made are to one another as 3:2. The part nearest to the player’s
finger is the longer. But such a proportion as this holds good only
for the actual operative lengths of the keys from the front to the
point where the sticker, or capstan screw is placed. For otherwise we
have a distinct change in the mechanical relations of the parts of the
lever-system, and this, of course, entails a corresponding change in
the forces that are brought into operation. It is therefore necessary
to have a standard length of key, as between the points mentioned, and
this length is placed at 15-3/4 inches. But, in order to maintain the
mechanical relations between the dimensions of the lever we must also
consider the depth to which the key sinks in front, and also the height
to which it rises at the back. If, then, we arrange that the depth in
front shall be 3/8-inch full and the rise in the rear 1/4-inch full, we
shall be able to maintain the position of the balance pin as already
calculated. Such a proportion supplies the very best arrangement. In
order to fix the proportions in the reader’s mind we repeat them in
tabular form, as follows:
Inches
Length between front of key and balance pin 9-9/20
Length between balance pin and capstan or sticker 6-3/10
Total length of key between front and capstan or sticker 15-3/4
Depth of fall of front portion of key 3/8 full
Height of rise of back portion of key 1/4 full
The front portion of the key is mounted upon a rail of the key-frame
which is provided with a pin. This pin works in a mortise cut in the
bottom of the front portion of the key and bushed with cloth. The pin
is oval in form and adapted to be turned so as partially to increase
the amount of space occupied by it whenever wear or age tend unduly to
enlarge the size of the mortise.
The exact size of all the various action parts that are mounted
above and in connection with the keys depends largely upon the exact
interior dimensions of the grand pianoforte case. So that it becomes
necessary carefully to measure the height from the key-bed to the level
of the strings, and also the distance from the front of the keys to
the line of damper lifter wires, and from there to the extreme rear
end of the key-bed. Likewise the exact position of the middle string
of each three-string group, the middle point of each two-string group
and the position of each single string must be marked upon a stick
for the guidance of the action-maker. The latter will then be able to
effect the correct alignment of the hammers, the rise of the escapement
lever and jack, and the exact position, in reference to these, of the
other parts of the action. It will, of course, be understood that
the proportionate dimensions of all the action parts depend upon the
measurements that we mentioned just now, as well as upon the dimensions
of the keys. The greatest care is therefore necessary in making these
measurements.
[Illustration: GRAND PIANOFORTE ACTION WITH METALLIC ACTION AND
DAMPER FRAMES, SOSTENUTO PEDAL DEVICE AND HAMMER SWINGING SOFT PEDAL
ATTACHMENT.
22. Sostenuto pedal-rod.
23. Attachment to damper-lever engaging with sostenuto pedal-rod.
24. Metallic action and damper-brackets.
25. Hammer swing-rail and cushion.
26. Hammer swing-rail rod.
27. Hammer swing-rail lifter.
28. Lifter-rod.
29. Lost motion compensating levers.
30. Lost motion compensating levers.
]
The junction of these parts with the damper mechanism lies within the
province of the action finisher and regulator and will therefore be
treated in the chapter on action regulation.
It will be observed then, to return to the consideration of the action
in its actual movements, that the depression of the key causes the
wippen to rise at its forward end. This brings the escapement lever (4)
to bear upon the roller (6), with which it is in continual contact,
and raises the hammer-shank and hammer-head (5) and (7). At the same
time the jack (3) is raised and its tail end is brought nearer to
the button (8), which it finally touches. As soon as this happens
the jack is tripped up and its head comes out of contact with the
roller. The latter in the meantime, having been raised away from the
escapement lever by the action of the jack, falls back into contact
with the former and is then borne up on the lever so that the hammer is
maintained in position near to the strings. The result of this is that
so long as the finger is held on the front of the key, the whole action
is continually in proper position to actuate the hammer. The jack is
not permitted to fall away, for the roller is maintained in the right
place by the escapement lever and it thus happens that a very small
angular motion of the key obtained by slightly raising and depressing
the finger, is sufficient to cause the whole action to be set in
motion, and the operation of actuating the hammer to be gone through as
often and as rapidly as required.
The pedal motions of the grand action are simple. The whole action and
keys, as we know, are mounted upon the key-frame together, and thus
form a homogeneous structure. The “_piano_” pedal is caused to shift
this frame so that the hammers each strike only two of the members of
each three-string group and only one of each two-string group. This
is effected by the use of a heavy spring that is set in the side of
the interior case and bears against the key-frame, and by a lever that
operates from a hole cut in the bottom of the key-bed and engages with
one of the bars of the key-frame. The pedal is connected with this iron
lever so as to shift the key-frame, and the spring operates to push the
key-frame back into place whenever the foot-pressure is removed from
the pedal.
The “_forte_” pedal simply pushes up the whole line of damper levers
(16) each of which is pivoted on flanges (21) for that purpose. The
lifting is effected by means of a rod connecting with the pedal which
is projected through the bottom of the key-bed and engages with a rail
set under the line of damper levers and adapted to raise them when
operated by the pedal-rod.
There are, however, two variations to the pedal mechanism of grand
pianofortes that require some attention on account of their mechanical
interest. These are clearly illustrated and described in the cut and
specifications shown on adjoining page.
The working of the sostenuto pedal and of the new soft pedal device
will be readily comprehended by reference to the cut.
It will be noted, in the first place, that the metallic action brackets
which were omitted in the previous drawing for the sake of exhibiting
the working parts more clearly, are now shown.
The “sostenuto pedal” is devised to permit the sustaining of a chord
while the fingers of the performer, for the purpose of continuing the
melody, are withdrawn from the keys. It will be observed that the
action is provided with a rod (22) which is connected with a pedal and
is adapted to be brought into contact with an additional damper-lever
(23). This additional lever is provided with a tongue of felt, and
when the rod is turned on its axis, this tongue engages with a similar
metallic device on the rod, thus holding the damper up as long as the
rod is kept in the position of contact. When the key is pressed down,
the damper rises to clear the string, and brings the additional lever
up with it, so that, if the rod is now caused to revolve, the tongues
on each engage one with another and the damper is held up as long as
the pedal is pressed down and irrespective of the position of the key.
Provided that the keys are first depressed, the pedal will always hold
up as many of the dampers as are thus raised. The result is to sustain
the sound of the strings after the hand has been removed from the key.
This gives a more permanent character to the harmonization of a melody,
without the dissonance that comes from the releasing of all the dampers
by the ordinary “_forte_” pedal. The “sostenuto pedal” is generally
situated between the others in the lyre or pedal case at the level of
the player’s feet.
The second device is also most interesting. It consists of a method for
softening the sound of the string, by a method similar to that which is
employed in the upright. It is claimed, and with some justice, that the
use of the shifting key-frame is attended with various complications,
and that the motion tends to hinder the adjustment of the action to the
strings. Moreover the hammers become unevenly worn by being continually
caused to strike two, instead of three, strings and this operates to
cause loss of directness in the hammer-strokes.
In this new device, the hammer is provided with a swing-rail (25),
having a cushion for the hammer-rebound similar to the ordinary cushion
that is supported upon the wippen in most actions, and a rod (26) for
pivoting it to the metallic action frame (24). The swing-rail also is
fitted with a lifter (27), which is operated by the soft pedal through
a lifter-rod (28). So far the process is simple. The effect of the
motion of the swing-rail is to bring the hammer closer to the string
and to soften the tone. But this is only accomplished at the cost of
lost motion between the capstan-screw and the key. To avoid the loss
of touch thus brought about, the lifter-rod is connected with two
compensating levers (29) and (30), which are so adjusted that they form
a continuous link between the parts where the lost motion would occur,
and thus preserve the continuity of touch and the weight that is lost
by the different actuating positions of the hammer. The ingenuity of
this device commends it to the student of pianoforte mechanism, and the
makers are entitled to great praise for the successful achievement of
this important modification.
We may conclude our survey by giving a list of the materials of which
grand actions are constructed.
Various Woods--
Pear tree Damper heads.
Holly Jacks and other small parts.
Sycamore Jacks and other small parts.
Ebony Tops of black keys.
Maple Hammer moldings and shanks.
Mahogany Hammer moldings, buttons, etc.
White pine Key-frames.
Felts and Cloths--
Baize On key-frames, hammer-rails, etc.
Baize Punchings.
Flannel cloth Bushing centre pin holes, damper lifter holes, etc.
Tone felt Upper and under felt for hammer.
Hard felt Bass damper wedges.
Soft felt Treble dampers, etc.
Flannel Sundry action parts.
Leathers and Skins--
Doeskin
Buckskin Various parts of action, operating faces of
Elkskin hammer-butts, etc.
Ivory Tops of white keys.
Celluloid Fronts of white keys.
Graphite Lubrication of working parts.
Iron Action frames, screws, etc.
Brass Centre pins, springs, pedal-feet, etc.
[Illustration: STANDARD AMERICAN UPRIGHT ACTION.
1. Key-rocker.
2. Abstract.
3. Abstract-lever.
4. Flange.
5. Action-rail.
6. Wippen.
7. Jack.
8. Jack-spring.
9. Check.
10. Check-wire.
11. Bridle-wire.
12. Tip of bridle-tape.
13. Bridle-tape.
14. Back-stop.
15. Regulating rail.
16. Regulating button.
17. Regulating screw.
18. Hammer-butt.
19. Hammer-shank.
20. Hammer-molding.
21. Hammer-head.
22. Hammer-rail.
23. Hammer-butt spring.
24. Hammer-spring rail.
25. Damper-spoon.
26. Damper-lifting rod.
27. Damper-lever.
28. Damper-lever spring.
29. Damper-wire.
30. Damper-block.
31. Damper-head.
32. String.
33. Continuous brass hammer-butt flange.
]
We are now able to turn our attention to the action mechanism of the
upright pianoforte. The historical chapter of this work contains a
short description of the early history of the upright form. Of course,
it will at once be seen that the only real mechanical difficulty
in designing a vertical type of pianoforte was to be found in the
department of touch-mechanism. The problem was indeed primarily of
the action. As such it is interesting to note the efforts of Hawkins,
Southwell and Loud, to produce an action that would approach in
efficiency that of the grand. It was Robert Wornum, however, who found
the solution, though not until nearly the end of the first quarter
of the nineteenth century. The principle applied by Wornum possessed
such value that it has never been superseded, and remains today the
distinguishing feature of the upright action.
We refer, of course, to the tape. As applied to the action of
uprights, this device has become universal, and all upright actions
in consequence have for years been everywhere similar as to general
design. Thus we do not find those radical differences of actuating
principle that to this day distinguish American from certain European
grand pianofortes. This is partly due to the fact that the great
battles had already been fought out when the first successful upright
actions were made. At present, the only remaining types of the ancient
“sticker” leather-hinged action are to be found in old-fashioned and
obsolete European pianofortes of the cheaper grade. None are made now,
however, except in the case of a very few worthless commercial English
instruments. In the United States the “sticker” action has hardly been
heard of.
Thus it seems unnecessary to give detailed drawings of any but the
accepted type of upright action. The reader’s attention is immediately
called, therefore, to the drawing herewith given.
The method of operation may be seen very clearly. Depression of the
key, to which is screwed the key-rocker (1), causes the Abstract (2)
and the Wippen (6) to rise. This brings the Jack (7) to bear against
the butt (18), which is raised, forcing the hammer (20) and (21)
through the shank (19) against the string (32). As the hammer strikes,
the rise of the jack has brought its tail against the regulating-button
(16), which trips it up so that it falls towards the back-stop (14).
The butt, being thus left free, drops back, assisted by the pull of
the tape (13), until the back-stop is caught and held by the check
(9), thus leaving time for the jack to get back under the hammer butt
through the aid of the spring (8). Repetition of the hammer is thus
assured, and while the rapidity of stroke cannot be so great as that of
the grand, it is sufficiently so to satisfy ordinary users. Sometimes a
spring is fastened to the front of the jack in connection with a silk
loop and cord which stretches back and engages with the hammer spring
(23). The latter is then fastened to the hammer butt instead of to a
rail (24). This arrangement gives a far more rapid repetition to the
action and causes it to approach the delicacy of the double escapement
of the grand.
[Illustration: UPRIGHT ACTION SHOWING LOST-MOTION DEVICE, METALLIC
REGULATING RAIL SUPPORT, CAPSTAN SCREW, JACK REGULATING RAIL AND
METALLIC ACTION BRACKETS.
34. Hammer-rail lifter-wire.
35. Hammer-rail swing-lever.
36. Hammer-rail lifter rod.
37. Lifter-rod lever.
38. Compensation-lever.
39. Capstan-screw.
40. Rail for limiting return movement of jack.
41. Metallic regulating rail support.
]
The pedal mechanism is the same as in the grand. The “_piano_” effect
is obtained by pushing forward the hammer-rail (22), so that the
hammers approach nearer to the strings. The “_forte_” pedal effect
is obtained by use of the damper lifting rod (26) which is turned
rearwards and forces back the whole line of damper heads so that they
leave the strings.
The lost motion that occurs in the action when the “_piano_” pedal is
used has been overcome in a most ingenious manner, and by means similar
to those already described in the discussion of the grand action.
The trouble to be overcome is the same, namely the lifting up of the
abstract from the rocker or capstan screw caused by the forcing of the
hammers towards the strings. This causes loss of touch and is very
irritating to the performer.
The drawing given herewith also shows the metallic action bracket
for supporting the action and the capstan screw that is used as an
alternate to the key-rocker.
The lost motion attachment operates through the rod (36) which lifts
the hammer rail and at the same time brings into play the compensation
lever (38), which takes up the space between the abstract and the
key that would otherwise intervene. Thus the touch remains true
irrespective of the position of the hammer.
The materials that are required for the manufacture of the upright
action do not differ from those, which we have already classified as
pertaining to the grand.
The adjustment of the upright action requires that the same precautions
be taken in the measurement of the key-bed, of the height of the action
between the keys and striking-point of hammers, the distance of hammer
from strings when at rest and so on. All these assist the action maker
to adjust the alignment of the hammers and the height of the abstracts.
The size of the pianoforte sometimes requires the omission of the
abstracts, in which case the bottom of the wippen is felted and brought
into contact with the capstan or rocker direct. All these details are
attended to by the action maker when the proper measurements are given.
The marking on a stick of the run of the strings is done just as was
suggested for the grand scale.
In conclusion, it may be mentioned that much similarity exists between
certain parts of the action of both types of instrument. It has become
customary to make the length of the hammer shank and hammer butt, when
fitted together, about five inches, counting from the center pin of
the butt to the middle of the hammer molding. This measurement will be
found correct for both grands and uprights.
The length of the hammer blow is always as nearly as possible 1-24/25
inches for the bass end, graduating to 1-9/10 scant in the treble.
These dimensions should be maintained at all costs. The key lengths
that we gave before are applicable to all forms of uprights. When
provided with these data the action maker will be able to put out a
mechanism that will fulfill the individual requirements of each kind of
instrument.
CHAPTER XIII.
REGULATION OF PIANOFORTE TOUCH MECHANISM.
We may presume that the reader is by this time quite familiar with
the appearance and use of the various parts of the grand and upright
pianoforte action, both as assembled and detached. We may therefore
proceed to give general instructions for the adjustment of these within
the instrument and the regulation of the various working parts into
proper harmony with one another.
We say “general instructions” advisedly; for it is quite out of the
question to teach action finishing and regulating by means of written
directions. Experience and the practical routine of the shop must
be gone through by anyone who hopes to be able to do this kind of
work well. For there are few departments of mechanical endeavor that
demand such skill, care, and patience as the regulation of pianoforte
mechanism.
Nevertheless the directions that we shall give in this chapter will
be sufficient to make him who reads and digests them a very efficient
critic. It is much to the employer to be able to estimate correctly the
value of each practical detail of the construction, and the correctness
of the manner in which it is executed. This chapter is intended to
provide as much of this knowledge as may be imparted by means of
written words.
We shall begin with the grand action, following the method that has
been pursued throughout this work.
The first step in the regulating and adjustment of the grand action
is taken by the “action-finisher.” He receives the action and keys
separately. The former is without hammers or dampers and the latter
without rockers or capstan screws. The action has to be placed within
the space destined for it in the instrument and the proper position
for it noted. If the action has been well made there should be no
difficulty in seeing that it fits its place correctly. The action is
screwed on to the key-frame through its metallic brackets and the
capstan screws are put into the keys at the proper points so that they
engage with the cushions on the bottom of the wippens. When this has
been done the weight of the action upon any one of the keys should be
noted and the action may then be removed. A piece of lead should then
be taken and fastened to the back of each key. This lead must have the
same weight as the action has upon each key. The keys will then remain
in their proper positions when the action is removed, and the work of
leveling them may then be begun. Remembering the depth of touch that
was prescribed in the last chapter, let the extreme bass and treble
keys be adjusted to an equivalent height by wooden blocks through their
front rail pins. Then run a straight edge over the keys and proceed
to adjust their levels by means of the thin paper punchings that are
provided for the purpose. These come in various thicknesses and are
laid over the balance rail pins and under the cloth punchings that must
first have been placed in position both on the balance rail and the
front rail. When the leveling is accomplished let the action be screwed
on again. Then let the hammers be glued on. The striking point of the
hammers must be carefully measured and the directions already given
as to the striking of the highest hammer must be observed. It will be
remembered that one-tenth of the string was recommended for the highest
hammers, graduating down to the ideal one-ninth and one-eighth. The
scale draughtsman will prepare a marking stick showing the true hammer
line. The hammers are glued on absolutely at right angles to the plane
of the strings. After they are dry, they must be adjusted to the proper
position by the capstan screws or rockers. They must lie just over and
not quite touching the wippen cushions. Let them also be aligned to
each other, horizontally, with great exactness. Be sure that the keys
work easily and that the depth of touch is roughly adjusted as already
provided for.
It next becomes necessary to fix the damper mechanism. This is chiefly
situated in the back of the action and the damper levers are to be so
adjusted that they rest a little above the backs of the keys, ready
to be engaged with them when the fronts of the keys are depressed.
The dampers must fit on to the strings straight and must drop with
sufficient force to effect an instantaneous damping. The damper levers
are leaded for this purpose.
The instrument is then taken in hand by the action regulator. His work
is most important. He first sees that the level of the keys is perfect
and that they are properly balanced when suspended without the action.
If any defects are found here they are remedied by changes in the
leading. The keys should be so leaded that they balance when tested on
a scale and the weight of touch with the action fitted must not be more
than two and one-quarter ounces.
The alignment of the hammers is then corrected and the length of the
hammer stroke, as laid down in Chapter XII, is adjusted by means of the
capstan screw or rocker. The jack is so regulated by its button and
screw that the trip up of the jack occurs when the hammer is 5/32 of an
inch from the string. The checks must catch the hammers when they have
fallen three-quarters of an inch away from the strings. The tails of
the hammer-moldings must be roughened and the checks be so slanted that
the catch is sure and tight.
The escapement lever is then considered. The spring that governs it
requires adjustment. It must be sufficiently strong to cause the hammer
to dance and jump a little on the lever when the key is released. The
escapement lever must also be regulated by means of the hook that is
found at its rear end. There must be space enough between the hook and
the lever to ensure that the catch of the hammer by the check is at all
times free. The screw that regulates the rise of the escapement lever
must also be attended to. It is necessary that the movement of the
lever be arrested before the hammer has quite risen to the point of the
trip up of the jack.
The after-touch under the front of the keys is regulated by means of
paper punchings. If enough punchings are placed under the keys to make
very hard pressure necessary to force a release of the hammer, then
punchings of 1/32 of an inch in thickness must be removed to make the
after touch correct.
The keys must also be made to descend evenly as judged from the top.
Unevenness is corrected also by the judicious use of punchings. In
regulating the dampers there are many small details to be watched. The
lifter-wires must work freely in the bushings and the heads must lie
straight upon the strings. This is especially important as regards the
bass wedge-dampers. There must be a small space between the damper
levers and the felted backs of the keys and the rise of the damper
heads when the levers are lifted must be even and facile. The height of
ascent of the damper heads must not exceed one-fifth of an inch, and
a little more when the whole of them are lifted by the pedal-rod. The
sostenuto rod must also be adjusted so that the damper lever tongues
are caught when the rod is revolved. Care must be taken that the rod
does not catch the tongues when the pedal is not in use.
The pedal mechanism is simple. It is essential to see that the feet
work in the lyre without scraping; hence lubrication with graphite and
tallow is necessary. The rods that connect with the action levers must
so engage as to be just in contact without bearing too much. The soft
“_piano_” pedal must engage with the shifting lever so as to allow a
small space between it and the point of contact with the key-frame.
The strength of the reaction spring in the case must be arranged so
that the key-board is pushed back with promptness upon the release of
the pedal. The “_forte_” pedal must be adjusted so that its connecting
rod is in contact with the damper lever lifting rail, but not enough
to operate without the depression of the pedal. The sostenuto pedal
requires to be arranged to revolve the sostenuto rod instantly. Here
the rod has to be revolved its entire distance before it operates and
the adjustment may therefore be made quite close.
These directions will enable one at least to be sure that the
regulation of a grand pianoforte action has been properly done;
although it is not to be expected that the innumerable small details
of practical work are to be learned other than practically. It must
especially be borne in mind that the use of tools and facility in
handling them and making definite adjustments with them is a matter of
long and patient practice. The above instructions are intended merely
to set the routine method before the reader, so that he may approach
the subject with a correct knowledge of principles.
The regulation and adjustment of the upright action is precisely
similar as to principles. The differences occur through the somewhat
dissimilar method whereby repetition is attained and the great
variation in the general position of the parts with reference to the
strings.
The action of the upright is fastened, by means of the metallic
brackets, to iron bolts which are set up in the key-bed. The height
of these bolts depends upon the dimensions of the instrument and the
striking point of the strings. In setting the action in place great
care must be exercised in seeing that the hammer line lies truly in
regard to the run of the strings. Errors in the casting of the plate
often lead to a distortion of the true string-line and the action
finisher must take care to set the action with due regard to these
matters. When the action, which is minus hammers and dampers, is thus
set in, the keys may be placed under it for the purpose of marking the
points where the capstan screws or rockers must be set. The hammers and
dampers are then glued in and adjusted for position with regard to the
strings. If the action and keys are truly proportioned, it is always
possible to make the length of the key just as recommended in the last
chapter. Sometimes the size of the pianoforte makes impossible the
employment of capstans or rockers with abstracts. In this case it is
customary either to use a dowel prop or to lay the wippen directly upon
the key. When the dowel prop is used it is driven firmly into the key,
and its upper end, which is a wooden rod into which the lower spike is
screwed, impinges against the wippen. In laying the place for the dowel
to be driven, it must be remembered that it is necessary for the head
of the dowel to hit the bottom of the wippen squarely. But the dowel
describes a curve at its head when the key is moving, and the wippen
has to be provided with a felted foot, curved so as to accommodate this
circular motion of the dowel. This motion must be observed carefully,
so that the dowel does not lay too far forward or back of the wippen
foot when the key is at either of its extreme positions. The regulation
proper now begins.
Abstracts, or dowels, are always regulated by a screw. This is either
in the form of a capstan or of a rocker, or of the movable part of
the dowel itself. The adjustment must be made with reference to the
position of the jack under the hammer butt. It is necessary that the
jack be just in contact with the notched heel of the butt. After the
hammers and dampers have been put in and their positions with reference
to the keys adjusted, it becomes necessary to regulate the escape
of the hammer by means of the regulating buttons and the jacks. The
directions given for grands apply here. The hammer springs must be put
in place and the fall of the hammers noted. If they stick, the bushings
are too tight or some cognate trouble exists which can be easily
remedied with a drop of oil on the affected part.
The checks must be adjusted to the back-stops and made to stand square
to them and they must also be arranged to catch the back-stops when the
hammer has recovered about two-thirds of an inch from the string. We
know that the length of the hammer blow should be from 1-24/25 of an
inch in the bass to 1-9/10 of an inch in the treble.
The tapes must be adjusted so that they begin to exercise their
pull when the hammer is started away from the strings. They must not
be strained too tight, but should be left just a little loose, so
that when the soft pedal pushes the hammers towards the strings the
abstracts or dowels do not at once leave the keys.
The dampers are adjusted, as to position, like those of the grand--that
is, they must lie square on the strings and be in a straight line with
one another. Their movements are directed by the spoons and these must
be so bent that the damper begins to move when about one-third of the
angular motion of the key has taken place. When actuated by the pedal,
they must fall against the back of the hammer spring rail, which is
felted for the purpose, and their motion must be instantaneous when
the pedal is depressed. The pedal mechanism is concealed behind the
bottom frame of the case and will be found to be precisely similar
to that of the grand, except as regards the mounting and pivoting of
the levers. These must be kept lubricated with graphite and tallow to
prevent squeaking. The connection of the soft pedal with the hammer
rail must be close so that instantaneous action results when the pedal
is operated. The motion of the pedal may push the hammers one-half of
their stroke length towards the strings, not more.
The leveling of the keys and the regulation of touch have already been
described; nothing further need be said except that these operations
are more easily performed in the upright owing to the open way in which
everything is set in.
It is unnecessary to go further into detail in regard to the regulation
of actions. Enough has been said to lay bare the general principles,
and, as was stated before, the rest comes from experience only. A
text-book can never replace an apprenticeship, but we cannot deny its
value in laying down correct principles for the man who wants to know
how things should be done.
As a fitting conclusion to the present discussion, we may now note the
order of the various processes which combine to make up the manufacture
of a pianoforte, from the cutting of the lumber to the final tuning in
the wareroom.
The various kinds of lumber that are to be used are exposed, after
cutting and rough dressing, in a lumber-yard. Here they remain from
three to ten years according to the kind of wood and the degree of care
that is taken by the manufacturer. The best makers take the greatest
care in seasoning their lumber.
The first operations to be considered are those of the saw-mill.
Here the rough work for the case-making is done, and the moldings for
actions and cases are turned out. The rough cases are then sent to the
case department and made up into shape. The bent rims are there glued
together for the grands, and the sides and frames of the uprights are
shaped. The back framing, wrest-planks and other parts of the case and
back construction are also put together in the case department.
In the meantime, the machine work has gone in the rough from the
saw-mill to the “action department,” where it is cut, shaped and
made up into the delicate action parts. These have to be leathered,
felted, provided with brackets, springs and the other accessories and
assembled. The hammers are covered, dampers, prepared, and the whole of
the action work is thus made ready against the time when the case shall
be in condition to receive it. This action and hammer work is generally
done by specialists, who supply many different makers with actions
according to their particular scales and patterns.
Meanwhile the cases have been sent to the varnish room and are here
prepared with filler and stain to receive the varnish finish. The best
instruments have their cases left about four months in the varnish
room, receiving eight or ten coats at intervals of ten days or more.
While this is going on, the sound-board department is occupied in
preparing the sheets of spruce for manufacture into sound-boards. Here
great care and skill are necessary to obtain the proper gradation of
thickness at all parts of the board’s surface. When the boards are
finished, they are put into drying rooms, to remain until wanted for
ribbing, bridging and insertion within the instruments.
The first operation in the assembling of the parts is performed by the
“bellyman.” He takes the sound-board, ribs it and affixes the bridges
according to pattern, bores the tuning pin holes in the wrest-plank,
and fastens on the iron plate, which was cast to pattern in the iron
foundry, to the back, upon which the completed sound-board has by this
time been glued.
Then the “stringer” receives the bellied back, puts on the strings and
pressure bar (if the latter is used instead of agraffes). The first
rough approximation to pitch is then made by the “chipper,” who pulls
the strings up roughly two or three times in succession at intervals of
about twenty-four hours.
The case is then turned over to the “side-gluer,” if the instrument
be an upright. The case of the grand is incorporated with the back and
is put together before the bellying. The side-gluer affixes the sides
and key-bed of the upright and also the bottom-board, which contains
the trap-work for the pedal mechanism. If the instrument be a grand
this department confines itself to the fitting and adjustment of the
lyre. After the sides are thus affixed the case is returned to the
“flowing-room,” where the final coat of “flowing” varnish is carefully
applied. This requires ten days to dry hard.
The case is now ready for the “action finisher.” His work of setting
in the action and keys and putting the instrument into rough playing
condition has been described in detail.
The pianoforte is then given its first rough tuning by the
“rough-tuner,” who surrenders it in turn to the “fly-finisher.” In this
department the top and bottom frames, fall-board, panels, key-blocks,
name-board, key-slip, hinges, music desk and other parts of the cabinet
work are adjusted and fitted. After fitting they are removed from the
case and sent to the “polishing department” to be made ready for the
final setting up.
The next operation is performed by the “action regulator.” His work,
which includes the finishing touches to the adjustments made by the
action-finisher and side-gluer, has already been gone over in detail.
The instrument is by this time ready for another and somewhat more
careful tuning. Here appears the “second tuner.” The instrument then is
permitted to remain in its existing condition until two more tunings
have been given at intervals of a week.
The “fine-regulator” next takes the instrument and proceeds to review
the work of the action-regulator and correct any deficiencies in touch
or repetition that may have been effected by the pounding of the rough
tuners.
The “tone-regulator” is next called upon, and his delicate work is
needed to give to the pianoforte evenness of tone throughout and an
agreeable quality.
Then the polishers rub down the sides, the smaller parts being already
polished as noted before, and give to the instrument its glossy and
mirror-like finish. The “setter-up” then puts the various cabinet work
parts together and the “fine-tuner” gives the final tuning. Lastly, the
superintendent looks over the whole work, and woe betide the unlucky
wight who has slurred or skimped his part.
The details listed above are, of course, subject to variations in the
order in which they are performed. The variations are according to the
practice of individual shops. Of course, it may at any time be required
to give more tunings, especially if the pianoforte is left on the floor
of the factory very long. But there should never be less than four or
five.
When the instrument is sent to the wareroom or shipped to the dealer
extra tunings are given according to the caprice or knowledge of both.
CHAPTER XIV.
TUNING AND TONE REGULATION OF THE PIANOFORTE.
The art of tuning the pianoforte is one of considerable complexity and
obscurity. During all the time that has elapsed since the key-board
instrument first came into being, controversies innumerable have raged
over the multifarious questions that the practice of the art implies.
This distressing state of affairs is primarily due to the fact that a
system of “tempering” the sounds produced by key-board instruments is
necessary, in order that playing in more than one key may be possible.