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courtesy of Hans Johannssen When the violin maker starts preparing to make an instrument, he must first of all consider his choice of materials and create a strategy of design. The rough flitches of wood used for the front and back plates are glued together with joints that must last perhaps for hundreds of years. To shape the outline of the thin strips of maple called the ribs, a mould is made which is later removed from the structure. The front and back plates must be worked fairly thin to be able to resonate easily, but because they must also support a lot of tension, they are shaped into a very exact arching. The edges of the thin plates are then reinforced by the inlaying of the purfling which also serves the purpose of adding visual style. Once the outside arching of the plates has been shaped, the hollowing of the inside can begin. The graduation of the plates to the proper thickness along with the cutting of the sound holes and fitting and glueing the bassbar are really the most difficult aspects of violin making. No two pieces of wood have the same properties and must therefore be worked differently every time. The carving of a scroll on the end of the neck of as stringed instrument has a long tradition and probably has symbolic archetypal significance. After the finished instrument has been coated in a glorious veil of tinted varnish, it can be adjusted tonally by means of the sound post and other aspects of the final fitting up.
Renaissance people believed Pythagoras' teaching that beauty was the result of perfect number ratios. The shape of the instrument is designed to withstand forces and direct them to a state of equilibrium, and the beauty of the curves is a direct and unavoidable consequence of this. The design of the classical instruments was of course influenced by renaissance thinking, where mathematics, harmony and knowledge of aesthetics was fused from a variety of disciplines including architecture, painting, astrology and music. In these times it was quite common for a chemist to delve into music, philosophy and painting, and a painter to study astrology and mathematics. There is strong evidence to support the fact that the classical violin makers employed geometric construction involving the influence of the early Greek and Roman theorists such as Pythagoras, Plato and Vitruvius, although there seems to have been a fairly free execution of these principles.
The glue used for all joints of the stringed instruments is traditional hide glue made from converted collagen. Although it is a very strong glue, able to hold wooden parts together with great force, the joints must be perfect. Hide glue is not an adhesive that fills gaps, so the plane iron has to be honed to a razor sharp edge and the joints planed with great precision. The main benefit of hide glue in the construction of musical instruments is its reversibility. Quite often instruments have to be repaired and restored, and hide glue will always come apart without the danger of damage if the repair is properly done. The use of synthetic glues such as PVC and the like to repair instruments has done more damage than anything else. The joints on a violin include simple butt joints such as the center joints of the plates and the complex joints of the neck. It must be considered of prime importance to the health and longevity of the instruments to have the joints in order. It is thought that the early Egyptians may have been the first to extract glue from pieces of skin with water. Traces of hide glue have been found holding ancient artifacts together. In the early days of violin making, glue making was a well founded tradition in many of the arts, although it was made by each individual craftsman rather than by specialized manufacturers. Glue, like gelatin are products of the action of heat and water on collagen and can be extracted from skin or bones. Hide glue is superior to bone glue and is generally used for making violins.
There are two main traditions concerning the making of the rib structure. On the one hand there is the Italian method which involves the making of a relatively thin inside mould which follows the inner contour of the ribs themselves, and the so called French method which employs an exterior mould, usually wide enough to accommodate the complete height of the ribs. The six blocks are cut and fit into recesses in the mould and then temporarily glued to the mould. When the blocks have been shaped to the final contour of the ribs, the ribs are bent on a hot iron and made to fit the shape of the mould and eventually glued permanently to the blocks. When the two plates are finished, the ribs can be removed from the mould and glued to the back or belly.
The ribs are glued to the six blocks which remain as a structural reinforcement on the interior of the instrument. As the surface of the ribs facing the plates is not large enough to form a good joint, 12 linings made of spruce or willow are fitted and glued to the inside of the rib facing the plate. Also the linings tend to add strength to the whole rib structure.
The exterior contour or arch of the back and front of a violin are carved to the shape using gouges planes and scrapers. The shape of the arching is made to give the thin plate of wood enough resistance to the lateral push of the strings and to distribute that push evenly over the plate. There are many variations possible for the shape and height of the arching. High and full, low and flat, scooped etc. each particular arch shape forcing the plate to vibrate in subtly different modes. The arch is also a feature of the aesthetic whole of the instrument which determines a makers style.
The purfling or inlay which is traditionally incrusted into the edge of violins and various other stringed instruments has a twofold function. Most importantly perhaps, it protects the thin, fragile edges from continual wear through years of constant use and damage. Because it is inlayed to approximately half the thickness of the edge it prevents the further continuation of cracks that often begin at the vulnerable end grain of the plates and tends to hinder the process of edge wear due to contact with the fingers and hands of the player. Perhaps equally important is the aesthetic function of the purfling. The contours of the outline of the plates are enhanced by a visual trick, that makes the appearance of the shape of the instrument more prominent. The total look of the outline can be expressed in an infinite variation of modes by the proportions between the relative thickness of the whites and blacks to one another and to the distance from the edge.
The bass bar is a length of spruce cut with the grain running in the same direction as the belly, which is glued to the interior surface of the finished plate. It lies lengthwise under the right foot of the bridge about 265 mm in length. The bass bar must be fitted with great precision to the inside of the plate, but opinions vary on whether it should be glued in with spring (tension). The function of the bass bar is primarily to allow the right foot of the bridge to displace a larger area of the front when amplifying the lower notes, since the plate would flex in the immediate area of the bridge foot due to the comparative thinness of the plate. The mode of vibration of the instrument at frequencies below 600hz is decidedly asymmetrical, where the sound post keeps the belly relatively rigid on the left side of the instrument and allows the right side of the bridge to effectively vibrate the bass side of the plate with fairly large oscillations. A secondary function of the bar is to reinforce the belly against the push of the strings. The shape of the bass bar determines the distribution of the forces that act on it, and the height and weight of the bar influence strongly the timbre of the instrument by determining the inherent resonance of the most active vibrating part of the instrument, the belly.
The scroll is the only part of the instrument which serves no real purpose, except maybe to hang it up by. It is however an important aesthetic addition to the baroque concept of the violin family instruments. It is an important part of the expression of the violin maker in terms of style and adds to the visual whole of the instrument. The origins of the scroll are to be found in the traditional schools of classical architecture, namely the spiral of Vignola and the spiral of Archimedes.
The fitting up, or, setting up of the instrument includes many aspects but generally involves the fitting of the sound post, fitting of the bridge, fitting and shaping of the fingerboard, nut and saddle, and the shaping and fitting of the pegs. As each sound post will have to be treated as a unique piece for every instrument and player, so does the bridge have to be fitted and cut to match the musicians personal tastes and the behavior of the body of the instrument. It is up to the skill of the maker to determine the ideal shape,cut and weight of the bridge for each instrument.
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The woods traditionally employed for the
construction of the violin family instruments are maple or sycamore for
the back, ribs and neck, and generally spruce for the belly. The variety
of maple used most generally is the Acer Pseudoplatanus and Acer
Platanoides. The maples are medium sized trees with long-stalked,
palmately lobed leaves, small regular flowers and a characteristic
winged fruit called a "samara" or key, borne in pairs. 
The spruce used most often for stringed instrument fronts is the Picea
abies or the Picea excelsa, the common Christmas tree, with its whorled
branches, narrow needlelike leaves which are borne on short peglike
projections of the stem. It is sometimes said that wood suitable for
violins is that which has grown at high altitudes and has had to suffer
harsh conditions such as cold weather and poor soil. While this might
seem slightly myth oriented, it is nonetheless true that wood which has
grown too quickly in lush environments and rich soil, generally tends to
be less resonant and less able to withstand the stresses it is subjected
to in the finished state. It is also a well known fact that air dryed
wood, seasoned for some years, without being kiln-dried is far better
choice. This is especially true for musical instruments which are shaped
to a thin form and must bear the considerable tensions of the taut
strings. If fresh wood is used it will invariably distort, check and
split. The violin maker bites on his wood to try to tell whether it will
be strong enough. He lets it fall and listens for its ring. He will try
to go by "feel"
The ribs are the 4-6 strips of maple or sycamore which make up the
structure separating the back and front of the violin. They have a
secondary vibrational function, but contribute considerably to the
transmission of vibrations between the back and front of the instrument.
They also define the volume of air inside the whole structure, along
with the interior shape of the plates. The ribs are bent with heat and
humidity to conform to the shape of the mould. There are two principal
types of mould for the making of the ribs: 1.The interior or Italian
mould and: 2. The exterior or French mould. The ribs are occasionally
also built without a mould on a flat wooden plate or on the back itself.
Making a violin requires great patience,
especially when it comes to the graduation of the thicknesses, as each
individual piece of wood has its own properties, being a natural
material. It takes a long time to shape and thin the wood, tapping and
flexing it until the maker is satisfied with the response of each piece.
When it comes to the hollowing of the plates the maker is confronted
with one of the more difficult aspects of the making of an instrument.
One of the reasons for the difficulty of mass producing violins is the
fact that the wood never has the same properties, even pieces of spruce
or maple from the same tree. When the flitches of wood are held and
struck with a blow of the fist, some pieces are found to vibrate loudly
with a long ringing tone, whereas other pieces sound dull and the note
dies away quickly. Of course there are also qualitative differences of
the wood such as hard and heavy pieces which will require different
thicknesses in the end as opposed to light soft pieces.
The sound holes with their curious shape, apparently ornamental, have a
great influence on the timbre of the instrument. Basically they
communicate the volume of air inside the instrument (which has its own
modes of vibration) with the outside air which is the medium in which
the waves are carried from the instrument. The size or openness of the
holes influences to a large extent the frequency of the vibrating mass
of air within the instrument, and therefore the selective reinforcement
of certain notes. The holes also influence the flexibility of the front
plate and consequently affect it�s vibrational patterns. They are cut
with a small fine saw and then finished with a razor sharp fine pointed
knife.
The sound post is a cylindrical piece of spruce
approximately 6 mm in diameter in the violin, which is fitted to the
interior of the instrument between the back and front. The sound post is
not glued in place but is held in position by the innate tension in the
instrument caused by the pull of the strings. The main functions of the
sound post are to reinforce the belly on the treble side, to affect the
vibrational behaviour of the plates and to counteract the forces acting
on the belly from the strings. The sound post is placed inside the
instrument with a sound post setter and gradually shaped to fit the
inside surfaces. The position of the sound post can affect the timbre of
sound and the playability of the instrument considerably, as can the
tightness. The Italian name for the sound post is "anima" or
the "soul" because of its changeable influence on the sound of
an instrument.
The varnishing of a violin has two aims basically. One is to permeate
the wood with a substance which can protect it from dirt and sweat .
Another aim is to cover the instrument with a colored sheath of varnish
proper which has a purely aesthetic function. The "ground" or
substrata which closes the wood can have a considerable influence on the
behavior of the sound by affecting the stiffness of the plate. The
colored varnish sitting on top of the ground, and wears off with time,
is meant to enhance the appearance of the wood, but can be detrimental
to the freedom of vibration of the plates if it is applied too thickly
or has too hard a consistency. the varnish should ideally be thin enough
and light enough not to constrict the instrument. The myths associated
with varnishes never cease to inspire the imagination. The "lost
secret" of varnish making has a pleasing allure to many. The
varnish on many classical Cremonese instruments is one of the great
achievements of violin making history. Whether it is possible or not to
recreate exactly the varnish of the classical masters is a subject laced
with fierce debate. It is interesting to note that the term
"secret" in renaissance Italy didn't have quite the meaning of
the word today, the meaning having been more on the lines of
"knowledge" but nonetheless apprentices were on oath it seems,
not to divulge the knowledge they had gained in the workshop of their
master to other regions, and the oath if broken could have serious
consequences.