Construction of a Violin

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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.

violin exploded view

 

Here are some very useful measurements of violin family instruments. Please let me know if you come across any mistakes or have suggestions on adding to or improving this list.

The Violin, The Viola, The Cello and The Bass

 



MATERIALS

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 peg like 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 dried wood, seasoned for some years, without being kiln-dryed 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. Normally 8-10 years are considered necessary to season quality tone wood. 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."

One of the benefits of felling a tree by yourself is the knowledge gained by going through the process of initially cutting and eventually seasoning the material. In fact violin making has fortunately conserved the idea through the centuries up until the present that thorough knowledge of the whole process from the rudimentary steps including the preparation of all materials is the key to a successful "feel" for the work as a whole. Even if you don't plan to fell trees from scratch always it is certainly a valuable experience to do it at least once or twice. Very important is to debark the wood as soon as possible to prevent insect and fungus growth between the bark and the cambrium. A treatment of the wood with borax solution is said to deter fungus which can cause staining and discoloration in the wood. I have been told that an initial storing of the trunk upright in the direction that the tree grew for some weeks is beneficial (possibly to do with settlement of sap that is still trapped in the pores. Storing the wood for the first few months is generally done outside under a simple shelter as rain or moisture is not detrimental to the wood at this stage except for the fact that a high moisture content attracts fungus growth and insects such as woodworm. Speculation as to whether the great masters of the seventeenth and eighteenth centuries treated their wood in some way will be ignored here and the accepted belief that air dried wood which is left completely intact is the best material to make healthy sound instruments of the future is correct. The traditional species used are spruce for the front (picea abies,norway spruce-known to violin makers as picea excelsa) and for the back, sides and neck, maple or sycamore-that is acer pseudoplatanus.

There are generally two ways to cut flitches from the tree trunk for violin family plates. One is radially from the core of the trunk and is usually referred to as being "on the quarter", and the other is tangentially on the perimeter and usually called "from the slab

Quarter cut and slab cut respectively

 

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DESIGN/PROPORTION

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.


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JOINTS/GLUEING

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 is a product 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.

The glue manufacturing process is basically the following:

*wash to remove dirt
* soak in lime water for 60-90 days
* wash to remove hair and lime
* neutralize with acid, drain, wash & drain
* add water, heat to 110-120 deg. F for 2-4 hours (called an extraction)
* drain off the dilute glue solution, evaporate, chill, dry, grind
* repeat last 2 steps 3-4 times to extract all of the glue with the temperature being increased 20-25 deg. F each time.


The process can lend itself to "home brewing" but it is messy and the aroma is found by some to be less than exciting! Your best bet is to buy the finished product from a reliable supplier.

CHEMICAL COMPOSITION
Hide glue is a protein derived from the simple hydrolysis of collagen which is a principal protein constituent of animal hides. Collagen, hide glue and gelatin are very closely related as to protein and chemical composition. An approximate chemical composition for glue is:

*Carbon 51-52%
* Hydrogen 6-7%
* Oxygen 24-25%
* Nitrogen 18-19%
* Total 100 %


The molecular weight of hide glue has a wide range from 20,000 - 250,000. The higher the gel strength, the higher the molecular weight.

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THE MOULD
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.  

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THE RIBS

The ribs are the 4-6 strips of maple or sycamore which make up the structure separating the back and front of the violin. It has been said that they have a secondary vibrational function, but contribute considerably to the transmission of vibrations between the back and front of the instrument. Nowadays with the advent of modal analysis and a new understanding of vibrational behaviour, it is more rational to think of the sounding body as a whole and that the ribs are simply part of the body, contributing to the manner in which the instrument vibrates by their stiffness and mass. The ribs also define the volume of air inside the whole structure, along with the interior shape of the plates. They 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.

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. The linings add strength to the whole rib structure, and consequently affect the vibrational behaviour of the whole corpus by stiffness and mass.


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ARCHING

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.

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THE PURFLING

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.

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HOLLOWING

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.

 

 


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SOUND HOLES

The aesthetics of shape is inspired by contemporary architecture

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 its vibrational patterns. They are cut with a small fine saw and then finished with a razor sharp fine pointed knife.

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BASS BAR

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.

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SOUND POST

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.

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SCROLL

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.

 

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FITTING UP

The fitting 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 behaviour 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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VARNISH

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 coloured 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 behaviour of the sound by affecting the stiffness of the plate. The coloured 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.

 

Click on the violin to see a beautiful example of a Stradivari varnish being examined in the shop recently.

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