Otis Tomas

To begin, light weight spruce blocks for the corners and ends are roughed out and temporarily glued to the mold. Except for the areas where the blocks will be glued, the mold is rubbed with wax to keep excess glue from sticking to it.

The ribs are rough sawn on the bandsaw from the same material as the back, then scraped to a final thickness of 1mm. This scraper is re-ground from a hardware store utility knife blade.

The rib outline is traced on to the surface of the blocks following the template.

The curves of the inner C bouts are carved into the corner blacks and the C ribs are bent to shape on a hot bending iron. I try to bend the thin ribs dry, but will sometimes use a little moisture to help with the tight curves of the Cs. For now, the outsides of the corner blocks are left full for support while the C's are glued into place.

The ends of the rib are cut square and clamped in place with a simple caul that simultaneously presses the rib ends onto the blocks and holds the rib tight against the mold. Throughout the construction of the violin, only good quality hot hide glue is used.

At this point, I will glue the lining to the ribs in order to protect the fragile wood. I use willow here but any light wood will work. It bends easily and carves effortlessly into shape. The lining is 2mm thick and 7 mm in height. The mold has been thicknessed to 18mm, so when the linings are seated down to the surface of the mold, I will have rough rib height of 32mm. The ends of the linings for the Cs are tucked in behind the blocks by making triangular knife cuts into the edges of the blocks, and correspondingly fitted lining ends.

The lining is glued in place. These little c-clamps are great, but clothes pins will work too. When clamping, I will sandwich the rib between the lining and a small bent scrap of thin wood on the outside, This not only protects the rib from footprints from the clamp, but helps to even out any irregularities in the curve of the rib from bending the highly figured curly grained wood.

Now I'll continue bending the other ribs. The rest of the blocks are shaped and the points of the corners are feathered to a knife edge where the upper and lower ribs will be joined. Here, I have selected a one piece lower rib, to complement the one piece back and top.

The rest of the ribs are glued and clamped in place with some shaped cauls to keep the rib ends tight against the blocks.

The remaining linings are then glued in place, the ends of the corners are trimmed, the surfaces are leveled, and the rib assembly is complete.

With the rib assembly completed, its's time to turn our attention to the back. First, one surface is planed flat and to a rough thickness of about 18mm (this will be lowered to around 16 in the course of carving the arch).

Then, the outline is traced from the rib assembly using a small washer to provide an even overhang of about 3mm. The back is then cut out with the bandsaw and cleaned up a bit. The finalizing of the outline and overhang will wait until just before the purfling channel is cut.

So far, the construction of the rib assembly has been a fairly routine operation. With the carving of the arched plate, we are approaching the heart of the violinmaker's art. There are various schools of thought and different theories about this and my own practice continues to change through the years. Without a doubt, the shape of the arch plays a significant role in shaping the tone of the instrument. The earliest violins tended to have a fairly high arching profile. The classic Cremonese violins of Stradivari and Guarneri featured a lower and more streamlined profile. I don't necessarily think of these changes as progressive improvements, but more as a reflection of changing musical taste and tonal objectives. To illustrate that shape makes a significant contribution to vibrational behavior, think of a musical saw. Tt retains all the same properties of size, material, and density, but by changing the shape of its curve, a huge variety of tones can be brought out. A simple and full circular arch rising from the purfling to the centre line is quite stiff and offers a lot of resistance to deformation. An arch rising in a low S-shaped curve has a lot of built-in spring and flexibility. For a violinmaker, it is not a matter of maximizing one or another quality, but of seeking a balance that is in accord with the kind of sound one is seeking. We need a certain amount of strength and resistance to give the tone a solid core that you can "dig into" with the bow, but at the same time we need a certain amount of compliance, sensitivity, and a light, quick response. Much of the challenge of violinmaking is to try to reconcile such opposing qualities, not by supressing one or the other, but by bringing a harmony between them.

I'll start carving by establishing a flat ledge around the perimeter of the plate. This will make the purfling easier, and when the carving is finalized, it will be gently hollowed out to blend in with the main arch of the plate. I leave this at a width of 15mm in the upper and lower bouts where the arch will be rather low and scooped, but narrowing to about half that through the waist where the curve of the arch will be higher and fuller.

The ledge is finished to 4mm thick in the upper and lower bouts, slightly more in the waist, and swelling gently out to the tips of the corners. Then I proceed to forming the long arch from the neck to tail. The shape of this arch has sometimes been described mathematically as a catenary, the shape taken by a chain freely suspended from two level points. There is a fair bit af variation to be found in the archings of various classical violins, and there is no need to idealise the description of these forms unnecessarily, though for the mathematically inclined, it can be an interesting study. When I look at the arching, I am more interested in trying to come to a more intuitive understanding (of course based on years of experience where I was more interested in copying other models). I try to imagine myself into the material to get a sense of the static loads required, the pressure of the soundpost and the twisting of the body with the pull of the strings. I am aiming for a simple, efficient, and restful strength where all parts share the load equally, but yet will be sensitive to the subtlest of vibrations. The sense of judgment in these things develops with experience or least the confidence that allows the freedom to work in this manner.

Arching guides or templates made from existing instruments (or mathematically generated) can be of help, but I find that the best tool for this long back arch is a flexible 12 ruler that can be used as a spline -- when bent to the surface it will easily show up any irregularities and provide a smooth, fair, and efficient curve. Still, the ends of the arch should be judiciously recurved to allow for greater freedom and flexibility.

After the long arch has been finished to my satisfaction, I turn now to the transverse arching, which so far has been left rough and full. The traditional arching guides (or "quinte") are as set of 5 templates that are placed across the plate at the widest parts of the upper and lower bouts, the narrowest part of the waist, and in the hollows of the transition from the bouts into the corners. Any number of these are available from books, drawings, plans, or existing instruments. For the mathematically minded, there is an interesting construction for these curves that has been getting attention in recent years: the "curtate cycloid", which is a mathematical curve that is drawn by tracing a point within a circle as that circle rolls along a straight line. If the circumference of the circle is the length of the desired arch, and the distance of the point from the centre is half the height of the desired arch, then the curves traced are a remarkably close fit to those seen in many classic violins (that is, as long as the proper adjustments are made to the end recurves, and a bit of allowance is made for normal discrepancies and distortions).

These are all valuable ways of looking at the shape of violin's arching. But again, it is probably best not to rely too much on idealized conceptions. Violins are remarkably varied and each is unique. There is no single truth or outward formula that will guarantee a "perfect" violin. Ultimately, I think that the slow crystallization of one's knowledge and experience into a personal vision and sense of judgment is what can elevate the craft of violinmaking to an art. There was only one Stradivarius, but there should also be a place in this world for each of us.

Keeping all this in mind, the arching planes are used to finish arching, always checking for symmetry, smooth and efficient curves, and the proportioning of concavity and convexity in a manner that I hope will bring out a good balance of strength and responsiveness.

These little guys visited my workshop again last night. I think that it's their babies that are responsible for eating the holes through the outer layers of the nice spruce logs I had stashed in the barn. Now I know to make sure that all the bark is removed! They are cute, though.

The back is scraped to a clean surface of smooth, efficient curves. I keep in mind that the final scooping of the perimeter that will complete the arching will wait until near the end. For now, the outer edges stay flat at around 4mm. I like to do the final scraping of the arches at night, working with a single strong light, using the shadows to throw into relief any irregularities in the curves of the surface. Strong direct sunlight will work for this too.

The thicknessing of the plates is another major consideration for the tone of the instrument, and should be done within the context of the quality of the wood, the character of the arching, and the overall tonal objectives. Too thick and the plates will not be able to respond quickly and efficiently. The tone will be hard, bright, and confined. But too thin and the violin will become hollow, boomy, uneven and wolfy (as well as endanger the longevity of the instrument). The construction in general should be strong but light, again balancing the need for both flexibility and stiffness, a strong solid tone that is free, light and responsive. Violin makers tend to obsess over the graduations of the plates, probably because it is easier to quantify than the description of the complexities of the arching. Standard plans of the classic instruments give measurements, but dimensional measurement is just one way of looking at it. The same measurements will have different weights or densities in different pieces of wood. Tap tones are another tool that many makers rely on to adjust the thicknesses, since the frequency of the tones is a function of the density and stiffness. But there is no simple rule for any of this. They are all valuable ways of getting to know your materials and designs, but it is the judgement of the violinmaker that balances one factor against another and tries to bring a proper harmony into the complexities that make up the violin. Real violins can be quite varied in all of this, and the numbers tend to be just averages.

The first step is to rough out the wood on the inside of the plate. Using a drill press with a depth stop, the plate is peppered with holes. In the central area between the inner bouts, I start with about 6mm and 4mm in the upper and lower "lungs". Then, I quickly chop out the excess with a gouge until I come close to the bottoms of the holes. The early classical makers would not have had a drill press, but a graduation marker consisting of a frame with a lever equipped with a marking awl that could be adjusted for different thicknesses.

The gouge is followed by the arching planes. After the initial planing I will recheck the thicknesses with the caliper and drill a new set of guide holes, this time coming a little bit closer to my expected finished thickness. A good average measurement for this would be around 4.5mm in the centre, and about 2.5 in the upper and lower areas, a bit thicker around the edges (I'll plan to leave some extra thickness around the edges for a final outside graduation after the instrument is assembled.

I go back and forth a number of times between the marking holes and the planes, slowly approaching the final graduations. As I thin the plates I will pay more attention to not only the measurements, but also the weight and the tap tone (by holding the upper bout a little ways in from the edge and tapping in the centre, the strongly resonant "mode 5" tone can be isolated). The general idea is to lower the weight (a good final weight for the finished back might be around 110 grams) but keep the tone up (around an F is usually good) while keeping close to the usual thicknesses. Normally, none of these factors will be too far off, but every piece of wood is a little different and it's good to be aware of all these aspects, balancing one against another, and aiming for strength, yet flexibility and response. None of the measurements are to be taken as the final word on any of this. Many famous violins are found to vary quite a bit from the "standard" measurements, but these are the tools and materials that the violin maker has to work with in making the decisions along the way that will determine the character and voice of the finished instrument.

I'll finish with the scrapers to smooth out the plane marks, using my fingers to look for any irregularities in the graduations, keeping the curves and graduations smooth and continuous. Because I like to finalize the graduations of the plates afterwards, from the outside, I will plan ahead and leave things just a bit heavier than I expect them to finish. Rather than finish each part as I go, I prefer to work the instrument as a whole as much as possible, and do the finalizing only after I have brought all the parts together.

Now its time to take the ribs off the mold. A sharp crack with the chisel and the corner blocks are split free. The end blocks are separated from the mold and the whole rib assembly can be stretched to allow the linings to clear the mold for removal.

The insides of the rib assembly is cleaned up. Excess glue is scraped off, the insides of the blocks are shaped, and the linings are trimmed to a triangular profile. The aim is to lighten it up, removing whatever material is unnecessary to the structure. The finished rib assembly should weigh no more than 50 grams.

The ribs are then aligned and clamped to the back. Glue is worked in one section at a time, excess is cleaned up, and then the entire assembly is set aside to dry.

Before starting the purfling on the back, the outline is finalized. I even out the overhanging edge, gently rounding the underside, and making sure all the curves flow smoothly, and with no irregularities. I pay special attention to the shaping of the corners -- much of the sculptural character of the carving is in the corners and edges, and this will determine how the purfling finishes out to it's characteristic "bee-sting". I don't rely too much here on measurements or templates. I hold it at arm's length, and use my eye to tell me if all the corners look like they belong together. Are they the same size? Do they point outward at the same angle? Do the curves flow outward to the tip in expectation of opening out?

Once the outline is finished, I mark the purfling lines with a two bladed purfling marker, being careful to keep it steady, upright, and snug against the edge of the plate. The lines are marked, then excavated with a sharp knife and chisel (made from a dental pick). Many makers will adapt a small router to cut the purfling channel. It's not as pleasant or peaceful but it can be made to work well. I'd rather put on some nice music and forget about time.

The channel for the decorative "knot" is carefully drawn out and incised freehand with the knife and chisel.

The purfling strips themselves are sandwiched together from maple veneer and ebony shavings. First I take some shavings from a straight grained piece of ebony, using a very sharp plane.

The curls are straightened by passing them quickly over the bending iron. The thicker white strips are sliced from a sheet of maple veneer.

They are then glued up in black-white-black strips that I slice in half and clean up with the plane. I use a regular modern cabinet makers glue. I find that it allows the finished strips to bend easier on the hot iron while still holding together.

The purfling strips are bent to shape on the iron. I start with the upper and lower bouts, tapering the tips into a fine "bee-sting" point, then I cut the waist strips to a nice mitered fit.

The purfling is scraped flush with the surface and it is time to turn our attention to the top. Since I will be using this nice one piece top, there is no need for the usual centre join. I will prepare it as I did the back, planing the surface flat, tracing the outline, and sawing it out on the bandsaw.

The top or belly is perhaps the single most significant factor in determining the sound of the instrument (though we should be careful not to overemphasize any single element, and keep the whole in mind). Good light weight but stiff spruce, perfectly quartered for maximum strength and efficiency is best for holding up under the long term static load from the strings bearing down through the bridge, while at the same time allowing an easy, light, and sensitive response to the vibrations.

The carving for the belly starts out much as for the back; a quick roughing out with the gouges and plane, and the establishment of a flat ledge around the outside of the plate. Then carving the long arch, guided by a template at first, but then finalized by the eye, hand, and judgment.

The shape of the top will differ from the back owing to its different function. Obviously it is is a more complex structure. It is the top that first and most immediately responds to the energy from the vibrating string as passed through the bridge. The important central area of the belly, under the bridge, is freed from the constraint of the sides of the body by the f-holes, and the upper eyes of the f's cut off and isolate all but a narrow "beam", the width of the bridge, through which runs the continuous grain of the top from the tail block to the neck. Whereas the back is being stretched as the result of the pull of the strings (thus pushing upward on the sound post) the top is uder compression, squeezed from end to end while pushing down under the feet of the bridge. The post provides support under the treble foot of the bridge while transmitting the load and the vibrational energy directly to the back, while the bar under the bass foot of the bridge gives support to the top and helps transmit the vibration through the belly.

The long arch of the top will be seen to take a certain flatness through the central area, while falling a little more steeply at the ends. The steeper slope at the ends gives a bit more flexibility here (you have only to see the effect of this on some very steeply sloped Stainer copies that tend to be weak and and become distorted here). For the cross archings, I will pay special attention to the narrow part of the waist, keeping a full strong arch there to help support the area at the ends of the f-holes, where the cross arching resumes its duty of supporting the long continuous central arch. As I start working the cross arching, I will also be guided by the way the f-holes lie. I will draw them in place to check their orientation as I shape the arching, and this will determine much of the way the curves will flow from the bouts through the waist. Looking at it from the side, I want to see that the main shaft of the f-hole lies parallel to the line of the ribs and that it lies about halfway up the slope. The upper eye of the f-hole will approach the top of the arch, while the lower eye will be dipping down just below the lower corner. Additionally, I will check for convexity with a straight-edge. I want to keep a nice continuous dome throughout the central area of the top. As I run a ruler across the top, parallel to the f-hole, I don't want to see any concavity until it approaches the shaft of the hole. This necessarily means that the narrow of the waist will have a broad full arch, while the upper and lower bouts are becoming low and scooped.

As I approach the final shape, I again use the shadows to look for irregularities and to check for elegance and symmetry of the curves.

I finish the top arching to my satisfaction; but as in carving the back, I will leave the edges flat and thick for now. The final shaping will wait until the whole instrument comes together.

Now I turn the belly over and start to carve out the inside. The procedure is similar to that of the back, but the top has a different function, and the graduations will be different than for the back. First, a quick roughing out with the gouges and planes.

The top is finished off to a more uniform thickness than the back. While the back stays fairly massive through the centre to provide substance and support under the post, the top is thinner, more like a vibrating diaphragm, and designed for maximum sensitivity. It will be finished off to around 2.5 mm, but as the finished dimensions are approached I will again check for weight, tap tone, stiffness and feel. Light weight, around 75 grams for now (I expect it to lose about another 10 g after the final scooping, edgework, neck and saddle slots, and finish scraping) and a tone around f# are expected. But all these numbers are negotiable depending on the character of the wood, the height and shape of the arching, the model, even the weather (and who knows -- maybe the phase of the moon?). It is the judgment of the individual violin maker, the educated guesswork, and the particular understanding of the kind of tone that he or she is looking for, that is what it really comes down to, and that inevitably makes every violin a personal expression and a unique individual.

The f-holes are now laid out for the last time and cut out. As they are delineating the important central vibrating area of the top, I will pay close attention to how they are formed, the spacing between the eyes, the distance between the shafts at the bridge line the length of the holes and placement of the holes can all play a role in influencing the instruments response. A tighter area between the holes can make for a quicker response, whereas a broader span can bring more area into vibration directly from the bridge.

The eyes are first cut through with a drill or a small gouge, then shaped with round files to their proper size and shape. Then a line is cut with a fine jewelers saw blade through the centre of the outline. A sharp knife then finishes by paring away the material to the line

I then round off the inside edges of the holes and prepare the bass bar from a piece of good straight grained and quarter sawn spruce. This one is cut from the leftover of the billet for the top.

The bar passes directly under the bass foot of the bridge, and at a slight angle to the grain of the top. Sacconi gives this angle as following a line that connects two points measure at one seventh of the distance from the centre line to the widest parts of the upper and lower bouts. Another way to look at this is that the angle of the bass bar mimics the line of the e string.

The bar is carefully fit, cut and try back and forth until it finally makes full, continuous contact with the curving inner surface of the belly. Some makers like to "spring" the bar slightly so that there is a bit of upward tension under the foot of the bridge. This is done by fitting the bar so that either end is raised a couple of millimetres from the surface, but when pressed into place for gluing, there are no gaps or wobbles in the fit.

The bar is then cut to size. It will be about 13 mm in height under the bridge and shaped to efficiently distribute the load through the length of the top. If you measure its height at different points along the length of the bar, you will see that its height actually increases in a straight line from the ends to the bridge line. Its shape is just altered to follow the contours of the top. I will check to see that the tap tone of the top, which lowered coniderably with the cutting of the f's, is now back where it was.

To finish off the top, I will then glue in a small veneer of wood to protect the soft spruce from the pressure of the soundpost. It is traditional to leave a slightly thicker spot here. I prefer to finish the central area of the belly to a uniform thinness, and add this slip of hard maple instead.

The entire inside is cleaned up for one last time, then I glue in my label and the body is closed. I will use a very thin glue here. I want to make it easier for a future repair person to open it up. Any fiddle that hangs around for long enough will eventually need the top to come off for one reason or another.

As with the back, the edge overhang is evened out, the corners are tweaked into shape, and all the curves are gone over to smooth and complete the outline to ready it for purfling. The soft spruce is much easier to cut, but the grain likes to pull the knife, especially in the areas where it changes direction at the widest limits of the bouts. A sharp knife and gentle pressure is needed. And one must be careful not to chip the delicate corners inside the purfling line.