Bandurria Construction

Raymond Varona Varona Lutherie rvarona@mindspring.com http://rvarona.home.mindspring.com

Contents

Introduction

Tools and Materials

Design Overviews

First Steps

Body Construction

Neck Construction

Assembly

Binding

Fretwork

Finishing

Design Overviews Just as one can’t argue that red is a prettier color than blue, one can’t argue that once bracing scheme is better than the other. Each one has their advantages and disadvantages, and on top of that, some luthiers will find that their particular touch suits certain designs more than others. Besides, no matter how wild or eccentric you design the bracing scheme, I’m 99.9% sure it’ll still sound like a Bandurria. In fact, the only way you can go wrong is sitting there thinking about it all day instead of making shavings, so let’s start getting into details.

Traditional The traditional bracing scheme for a Bandurria consists of transverse bars, perpendicular to the grain, located at key points on the soundboard.

The first bar occurs just above the soundhole, followed by a second bar below the soundhole. A second, less common, variant uses two transverse bars with the bridge resting in between.

The braces are slightly smaller than the transverse bar for the single pattern. The other braces are longitudinal bars that reinforce the soundhole in the direction parallel to the grain. A square or circular graft can be used as well, although this technique is fairly common with Bandurrias. If a large or complex rosette is used however, this would be the recommended reinforcement.

From the Philippine Bandurrias I’ve inspected, there’s some variation when it comes to bracing patterns below the soundhole. The more common pattern is a pair of parallel transverse bars above and below the bridge, separated by 1-3/4”. The sides of the soundhole are typically reinforced by struts running parallel to the grain, butting up against the braces above and below the soundhole.

The bars tend to be relatively wide and short and the tops are fairly thick, usually around 1/8”. Dimensions for the bars vary from 1/2-3/4” in height, and 1/2-3/8” in width. The tops typically do not include an arched or domed top.

Parallel transverse bracing is perhaps the most common scheme for flat top instruments. Lutes, mandolins, citterns, bouzoukis, and early guitars all commonly use this method of reinforcement. Bracing in the transverse direction reinforces the wood of the soundboard perpendicular to the grain, which is both the weakest and least stiff orientation of quartersawn wood.

Bracing schemes of this sort are prone to ‘bellying’ or an undulating deformation when the instrument is viewed with the soundboard at a horizontal orientation. Instruments with a strings that are anchored to a fixed bridge exhibit an ‘S’ shaped distortion, which is usually more pronounced with ladder bracing due to lack of support in the direction of the string pull. Instruments with strings anchored to the tailblock that use a floating bridge simply dip down in the area around the bridge.

One of the main advantages of

this bracing system is the ease of implementation. There are no notches that have to be cut for brace intersections and apart from the simplified layout, errors due to brace misalignment are slightly more forgiving than other systems.

Bandurrias that are well built

with this bracing pattern typically have good volume and great sustain at the expense of response and immediacy of sound. Due to these tonal benefits as well as the safety factor from the thicker top and ease of bracing layout, I believe this system is the safest choice for the beginner while still offering excellent potential for advanced builders, despite its simplistic form.

The traditionally braced

Bandurria built in this guide will use 4 transverse bars: the upper and lower soundhole bars and a pair of bars above and below the bridge.

X-Bracing X-Bracing, where the main support consists of two braces joined into a crossing X configuration, is attributed to C.F. Martin Senior of Martin Guitar fame in the mid 19th century. Intended for use on gut-strung guitars, X-bracing really caught on once wire-strung guitars became popular in the early 20th century in the United States. Since then, X-bracing is the standard for steel-string guitars and is now becoming almost standard in flat top mandolins too. The main brace, the X, consists of two braces with notches cut in opposite ends and proportional depths such that the interlocking notches form a single joint, or lap joint.

The angles for this intersection typically range from slightly obtuse angles (100-110) to 90 degrees, depending on the desired cross-grain stiffness and the

shape of the soundboard. The X is shifted towards or away from the soundhole such that the bridge ends rest on an arm of the brace. While X-bracing is usually found in fixed bridge instruments were torque resistance is a primary concern, the X is also highly effective for floating bridge systems. Since the soundboard is reinforced in both principal directions, an instrument with this bracing scheme resists distortion more effectively than a strictly transverse bracing scheme. Additional braces in the upper bout include an upper transverse brace under the fingerboard and above the soundhole as well as two connecting braces connecting the X to the upper brace. These braces reinforce the soundhole area. In the lower bout, finger braces extending from the middle of the lower X out to the side provide cross-grain stiffness around the perimeter of the instrument, and sometimes a slanting tone bar inside the X provides support in the lower center of the soundboard. Some builders also use small cross-grain strips or cleats over unbraced areas of the top along the center seam. Due to the increased structural efficiency, the top of X-braced instruments can be thinned to a greater extent than parallel-braced instruments. However, attention to cross-grain stiffness of the soundboard is more important so the margin of error is slightly less.

Bent Top While the concept of a bent, creased, cranked, folded, etc., top has

been around since the Neapolitan Mandolins of the mid-18th century, these tops are perhaps most from the Selmer/Maccaferri guitar of gypsy jazz fame. Both the petite and grand bouche models featured flat tops that were bent cross-grain with heat and then arched in both directions, resulting in an extremely stiff but lightweight top. The resulting sound is a mix between an archtop and flattop; neither superior or inferior, but rather a different character entirely. The bracing for bent tops is primarily parallel transverse. However, the bend in the top provides a great amount of stiffness between the transverse braces where it is needed, so massive amounts of bracing parallel to the grain is not needed throughout the soundboard, apart from two braces connecting the bars above and below the soundhole.

The bracing scheme is similar to that of typical parallel transverse bracing. One significant difference is that the braces are curved to a relatively tight 6’ radius. Another change is that two braces are typically placed parallel to the grain and between the transverse braces underneath the area where the bridge ends touch the top.

Due to the increased stiffness from the arching, the tops for a bent top instrument can be even thinner than an X-braced instrument. The amount of bracing is also equivalent, so the entire soundboard typically weighs less. However, due to the added height from the bend and the negative neck angle that the sloping soundboard forms, the bridge needs to be higher, increasing the down bearing on the bridge and the resulting stress on the soundboard.

Lattice Bracing One of the most well received and successful alternative bracing schemes uses a grid of interlocked braces into a lattice pattern, hence the name. The advantage of a lattice pattern is that it increases stiffness all throughout the pattern, allow the top to be thinned dramatically. This is especially important in larger instrument such as guitars, where the soundboards alone can weight from 150-250 grams. Typical bracing schemes only weigh 30-50 grams, so if lattice bracing weighs either the same or 10-20 grams allowing the weight to decrease to 70-100 grams, the net savings are nearly half.

The lattice can be made of wood, although the for classical guitars, braces consisting of carbon fiber and balsa wood are common in the Australian style of building. Developed by Greg Smallman, the top is reduced to almost extreme thinness, with unidirectional carbon fiber composite strips laid out on top of a balsa wood base lattice. The balsa wood only serves to space the extremely stiff carbon fiber from the top, greatly increasing stiffness while

keeping weight down. Many other techniques such as a plywood rim lining, vacuum molded arched backs, and laminated sides all contribute to create an extremely responsive and loud guitar.

Like any other bracing pattern, a

lattice arrangement has many different possible arrangements. One of the first variables is whether to orient the lattice diagonally to the grain or along the principal directions. Due to the triangular shape of the Bandurria, a diagonally-oriented lattice seems to be the best fit.

By orienting the Braces diagonally, the top has ample support throughout its entire surface, which is especially critical if the top is to be thinned excessively. Lattice orientation in the principal directions works well in a geometric sense, although not quite as well as a diagonal lattice, particularly in the upper bout.

Another potential concern is the possibility of shear along the grain for the longitudinal braces. The transverse braces should prevent any splitting, but the grain is not reinforced to the extent of a diagonal lattice. If a thicker top is used however, this bracing scheme should work well. A slight variant on the diagonal scheme for use with a thicker top is to omit the lowest of the bottom cross-struts.

This omission helps to ‘open up’ the sound and tune the instrument to a slightly warmer timbre. However, this isn’t recommended for very-thin tops.

The Soundboard For all intents and purposes, the soundboard is what dictates the ‘voice’ of the instrument.

Soundboard Division Luckily enough, Bandurria soundboards are small enough that with some manipulation, one can easily get two soundboards out of a single guitar top set. Classical-sized soundboards work perfectly for this, although if you’re particularly nervous about space you can use a steel-string soundboard. If you can get better availability or pricing, flattop mandolin soundboards work well too. For the budget conscious, I highly recommend the AA-grade classical soundboards from Stewart MacDonald, especially if interested in some of the alternative methods such as lattice bracing where the stiffness of the top isn’t quite as critical. For the extremely budget conscious, you can even resaw brace stock or hardware-store boards, although this method will likely require more than two pieces. If you resaw your own stock, aim for about 3/16” thickness so that you have some room to work with. A bookmatched soundboard looks something like this:

This soundboard in particular is one of the AA-grade tops from Stewart MacDonald. There are a few spots of localized runout but the top is fairly stiff and well quartered. Additional color striking most likely downgraded this top, although I find it quite appealing. In order to get two soundboards, one set will come from the upper right corner and the other will come from the lower left. The divided soundboard appears like this, with dotted lines added along the division line for emphasis:

The division lines are marked by laying down a template and then marking the minimum boundary regions, with the extra space split between the two soundboards.

With this method, the bookmatch line is different for each soundboard. This means that if the grain progresses from tight to wide, one of the soundboards will have the wider grain in the center and the other will have the tighter grain in the center. The tighter grain is customarily in the center, but since grain width often has almost nothing to do with stiffness, it doesn’t really matter which way the grain lines progress. If you can’t stand the cosmetic look, save the ‘uglier’ top for an experiment.

The divide for the tops is then most easily cut on either a scrollsaw or bandsaw, as seen in the following photograph.

If you don’t have access to a scrollsaw, a handheld coping saw or a Japanese Dozouki will work. In a pinch, a coarse hacksaw blade used as a pullsaw can make the cut as well. If you use a longer soundboard, you can make a simple angle cut with whatever tool you want, but with these shorter classical soundboards the perpendicular cuts are necessary. The body template is then drawn on the resulting halves, shifted away from the bookmatch line a few millimeters in order to allow for some loss of material while jointing.

It typically takes only 1 or 2 mm at the most in order to joint a plate, but its always preferable to err on the side of caution. As you’ll notice in the above

photograph, there isn’t much spare space in the top or bottom of the template. Its plenty, but for the extremely cautious I’d once again suggest the longer tops.

Jointing In order to make one large soundboard from the halves, the tops need to be glued. In order to be glued, the tops first have to have perfectly matching edges that make contact along their face across their entire length. For those of you lucky enough to own a jointer, its as simple stacking the two pieces flush, passing them over, then admiring your handiwork. For the rest of us however, the best method of jointing is accomplished with a hand plane and a method known as shooting. Shooting is simply planing with the plane’s side walls gliding along the work surface with the plates to be jointed held parallel to the surface and slightly raised as shown below:

While I almost always use a low-angle block plane out of habit and familiarity, the preferable tool would be a well-tuned and trued smoothing plane. Even more preferable would be a jack or joining plane. While bigger is seldom better, in this case, a long, trued plane can make short work of jointing. With a little practice, the block plane works well too, as long as the user can develop enough

touch to know when to let up or dig in to smooth hollows in the line.

Before you take your first strokes, line up the plates and notice the highs and lows that prevent the edges from meeting. Either make mental notes or pencil marks and try to concentrate on the high spots while letting up on the low areas. Aligning the plates at the beginning as well as between planing sessions can either be accomplished with a sensitive finger or by resting the plates on a piece of plate glass or polished flooring tile. Once the plates are lined up, use a pair of small clamps to keep the plates aligned while planing. Make some marks on the top half as to which side is up and what direction you’re planing in once you start and maintain consistency as to your planing direction and plate order and orientation.

While I prefer to plane with one

hand while restraining the plates with my free arm, you may find planing easier if you have the plates clamped to the workbench. In that case, after aligning the plates, sandwich them between two pieces of lumber and clamp the assembly to the workbench. This makes checking the joint a bit of a chore, but provides for less chance of error while planing.

As you get closer and closer to

an invisible gap, progress to finer and finer cuts until you only produce dust at the end. You have a good joint if once you push the halves level the joint becomes invisible. If you’re really picky, try claming a pair of wood strips at the top and bottom ends, pushing the two halves together, and hold the assembly up to the light. The gaps are

visible through the light, while the good areas of the joint remain translucent.

If you have particularly stubborn

gaps, check your template to see where the gaps lie. If they’re in the area where the soundhole cutout will occur, forget about it. Since the area above the soundhole will be hidden by the fingerboard and reinforced from underneath, that joint also isn’t worth getting frustrated over, although its best to get all centerseam joints as good as possible whenever possible. Also, if your plane sides aren’t a perfect 90 degrees, don’t worry about it since once you turn the bookmatch over, the angles will be complementary. Do not, however, start planing in opposite directions such that you plane with the other side resting on the work surface.

If you absolutely cannot get the

hang of jointing, try taping sandpaper to plate glass and sanding the joint square and straight. While planed joints are the ideal gluing surfaces, running through the progressing grits of sandpaper up until 600 or so should make for an acceptable joint. If even using sandpaper doesn’t work, rough the edges of both halves with 80-grit sandpaper and join with epoxy. The glue line will probably be much more apparent than any other method, but it’ll work better than a poor joint with conventional glues.

Joint Gluing (Note that the gluing and preparation procedure will be different for the bent-top design)

Just like jointing, there are a large number of methods available for gluing your freshly-jointed plates. If your workbench has the equivalent of a long-jawed vise, clamping the plates together is extremely simple, as seen in the following picture:

The vise in the picture is built-into a relatively inexpensive mobile workbench. The stop on the right is stationary while the block on the left is advanced by the turn of a screw on the end of the bench. In order to apply clamping pressure on the top and bottom ends as well as the middle of the plates, fingerboard blanks are placed in between the stops and the plates and scrap wood is placed on the top and bottom ends, relying on the elasticity of the fingerboard to apply pressure to the top and the bottom with the direct pressure from the stops applying pressure in the middle. Prior to gluing, make sure that both halves are clear of dust. Also make sure the bottom surface of your gluing jig is clear of debris as well and that the anti-stick layer is drawn out taut so that it won’t get caught in the centerseam. Also make sure no chips are clinging to the surface of the soundboard, any sort of contaminant can put a dent in the soft top woods.

In order to keep the plates from buckling upward, place heavy objects of any sort on the plates. The center seam is left uncovered with a flat surface underneath so that both plates can be pressed level. This is most easily accomplished with a roller press, which can be found at any art store. Your finger will work well too. Make sure you use a piece of plastic or wax paper to prevent the squeeze-out from the centerseam from sticking if you use a wood or fiber-based surface underneath. If you use epoxy, use waxed paper. Be sure to clean up as much squeeze-out as you can before the glue sets. If there are still small bumps and irregularities, don’t worry and save it for the next step. If you do not have a convenient claming system, there are a number of methods that you can employ. One method is to clamp two pieces of lumber with a small gap remaining between the two halves and the lumber pieces. Then, tap some wedges into the gaps to apply clamping pressure. You can also clamp the two pieces a slightly smaller than the width of the halves then push the pieces from a triangular form to a flat form, clamping right on the centerseam and allowing the space to be taken up by vertical deflection. Keep the plates clamped to the glue’s recommended cure time. 24-hours is a safe bet for pretty much any glue. After the curing time, sand off any cured squeeze-out as well as any bumps and uneven areas with 150 grit and inspect the glue joint. If it’s not satisfactory or if some dust, debris, or wax paper got in between the joint, carefully saw down the centerseam and rejoin.

Bent Top – Forming the Crease The bend in the bent top, also referred to as the crease or pliage, is formed by applying pressure over a heated iron. Since bending is easier as the wood gets thinner, the top should undergo preliminary thinning before attempting the bend. Consult the section on plate thicknessing for more information about that step. After thinning the top, proceed to joint the top as with the other methods, but don’t aim for a perfect joint, just ballpark fit. This will make the arduous task of fitting the bent halves slightly easier. The goal is to make a 6 degree bend perpendicular to the centerline.

The end result is seen below.

Note the two spruce bars placed on both sides of the top’s edge. These are fixed with watered-down glue prior to bending in order to prevent splitting and enable the bender to apply greater force. The

other side is long enough to not require these reinforcements. The bars lie in a waste area and will be sawn off after the bend is complete. More information on bending can be found in the dedicated side bending section, but there are some specific notes about this procedure. The bend is most crucial in the central region of the soundboard. Since the top will be joined to flat sides, an emphatic crease towards the sides is not desirable. However, if you concentrate your bend on the edge of the center seam, you can cause an indentation in the center, requiring a lengthy jointing process to level the top and bottom of the soundboard with the indentation. If possible try and keep the entire bottom of the soundboard in contact with the iron but bias your pressure towards the center.

You can score the bottom of the soundboard with a knife to aid in bending, although remember to reinforce the scored line later on. Both spruce and cedar should take the bend with only a moderate amount of heat. Dry bending is preferable. If you feel you need water to make the bend, try leaving the top on the iron slightly longer before applying pressure or increase the temperature. Check the angle with a machinist’s protractor and aim for a slightly sharper

bend of 6.5 to 7 degrees to allow for springback. Let the top sit overnight and re-bend if necessary. Jointing is markedly more difficult with the bent tops. Due to the bend, the top must be elevated from the work surface and the joint must be continually flipped.

Proceed slowly and check your progress often. As with the previous methods, if you cannot get a good planed joint, try sandpaper or epoxy, as a last resort. Gluing the jointed top is similar to the other methods, although the tilt in the bottom half of the soundboard presents a slight problem.

Since the top section is longer, I prefer to let it rest on the flat surface and have the bottom tilted upwards. Use fingerboard-sized pieces on each side to apply pressure and insert the wedges for clamping. If your joint is good, simply aligning the raised bottom with your finger will often be sufficient, although

if more support is needed, coat two offcuts from the soundboard with sealer and use them as cauls on both sides of the soundboard’s bottom. Clamping both cauls should help maintain alignment.

Rosette Inlay In most traditional Philippine instruments, rosettes consist of bands of concentric purfling lines. I’ve also seen marquetry patterns as well as free-form inlays and I’m sure there are mosaic rosettes out there as well. The practical purpose of a rosette is to provide some support to the exposed end-grain of the soundhole, but for the most part the rosette primarily serves a decorative purpose. Purfling lines are probably the most simple inlay solution. The lines themselves are made from strips of veneer that are glued into place and scraped or sanded flush. Black and white are the most common colors, with maple or holly usually used for the white and dyed, or ebonized maple for the black colors. These lines can be purchased either individually or in pre-glued common combinations from luthier suppliers at a reasonable cost. For those seeking other colors or additional combinations, the easiest solution would be to buy the veneers in sheet form, which are readily available from a number of woodworking sources and then cutting them into strips. A spaghetti cutter or a heavy-duty paper shredder can make short work of this with only a few lost strips, or a hand-tool jig can be easily constructed.

For some of the best examples of concentric line rosettes, the guitars of the mid and 19th century are a good example. Spanish bandurrias are also typically decorated with concentric purfling rosette lines. Purfling lines can also be used to bind the soundholes, if desired. The thin purfling strips readily bend to accept most soundhole sizes and apart from the veneer cutting, the process is not labor intensive. The results can also be striking, particularly if dyed veneers are varying width lines are used. Marquetry is a form of inlay that consists of veneers that are cut, arranged and glued before inlaying into a recessed cavity. These patterns are usually repeating geometric patterns, such as checkers, alternating diagonal bands, arrows, etc. ‘Rope’ purfling on Weissenborn-style lap steels or ‘Herringbone’ purfling on Martin style guitars are one of the most recognizable and famous of marquetry purfling styles on musical instruments. Unlike purfling lines, these bands cannot be cold bent but must be bent over heat with great care. As such, marquetry isn’t as common as purfling lines for rosettes, but I have seen it in some cases and it offers some intriguing options. Spanish-style mosaic rosettes are similar to marquetry in that they are composed of pre-glued patterns of arranged veneers. The main difference is that the patterns are composed of small squares that form an intricate pattern similar to that of mosaic tiles. These patterns are designed similarly to the way pixels are arranged in digital art, then fabricated from long, square veneers that are then glued up in rows, then stacked into bricks. The resulting

mosaic stack is then sawn into tiles and then shaped and tapered so that it will fit the curvature of the rosette. This method, beginning with the advent of the modern Spanish guitar in the late 19th century has become the standard method of decoration for Spanish classical guitars. While I have yet to encounter a bandurria, Spanish or Philippine, with a mosaic rosette, I suspect they’re out there and if not, I’ll have one built sometime in the near future. Although shell inlay has been around for hundreds of years, particularly in baroque instruments, the popularity of inlay for the rosette has varied over the course of instrument building. Early shell inlay was typically set into the cavity with a tinted filler instead of fitted into a matching cavity. Inlaying into a fitted cavity became especially popular in the beginning of the 20th century and is becoming increasingly commonplace in custom instruments today.

However, by far the most common form of shell inlay in the body of the instrument is the use of shell strips around the soundhole and perimeter of the instrument. Most notable examples are instruments from Martin and Taylor guitars. One of the advantages of shell inlay in this form, particularly abalone shell, is that straight strips can be broken into small pieces and fitted to the curve with near invisible gaps. Larger strips from about 3mm upwards produce significantly more visible joints and require that the shell be cut to the proper curve and then carefully mitered to fit with the adjacent pieces. Pearl shell typically cannot be broken without visible joints. Shell line inlay is in my opinion the best compromise between

speed, ease of installation, and looks. The main downside is cost, which while not outlandish is considerably more expensive then the other options.

One of the more recent

developments in rosette designs is the use of figured wood bordered by purfling lines. Burls, curls, and spalts are some of the more common choices, although just about anything with interesting grain or color such as Macassar Ebony or endgrain Black Palm are stunning choices as well. Cutting and installing the rosette is fairly simple. Veneer can be used to widen the wood choices even further and provide a highly economical source of rosettes, although great care must be taken and the margin for error is very slim. However, with practice, veneer or solid wood rosettes offer a unique look with low cost and moderate effort, making figured wood my primary rosette choice.

For the instruments built in this

guide, shell strip and wood inlay will be used for demonstration. The bent top and X-braced bandurrias will use abalone shell, the lattice braced bandurria will use burled Walnut veneer, and the ladder braced bandurria will use solid spalted Maple.

Shell Inlay The process for shell inlay is relatively straightforward. First, a cavity is routed that will accommodate the shell and any bordering purfling. The purfling strips are then glued into place. Next, the abalone strips are fitted into the rosette channel, and finally, the abalone is glued into place.

Prior to routing the channel, use a compass to layout the rosette and make sure that you are satisfied with the balance and proportions. Stack your actual shell and purfling pieces and measure the width with a pair of calipers so that your outlines are accurate, since these will be your guides for routing. Be sure to trace the body outline on the surface so that you can see how close the rosette will be to the edge of the body. Also be sure to leave at least 4 or 5 millimeters between the edge of the soundhole and the start of the rosette. You can, of course, set the rosette closer, although in that case I would suggest binding the soundhole edge in order to keep the endgrain stable. Starting with the channel, the easiest method of cutting the channel is with a router and a circle cutting jig. In particular, I use a Dremel motor tool that attaches to a router base and circle cutting jig available from Stewart MacDonald. The assembly in use can be seen in the following picture.

The operation of the jig is quite simple and a homebuilt version isn’t difficult to devise. If using this jig or something like it, the first step is to drill a hole for the pivot pin. Make sure to choose a drill bit that is the same size or slightly smaller than the pivot pin. If you accidentally choose a larger bit, wrap the pivot pin in

Teflon until the fit is snug. It’s important to get the hole centered with the bookmatch line. Since spade-point bits have a tendency to wander, punch a small pilot hole with an awl and drill slowly. In fact, you can even turn the bit by hand and have the hole drilled in a minute or two while maintaining excellent control. Since the top most likely won’t be thick enough to hold the pin stable, use the same bit to drill into a sheet of MDF, Baltic Birch ply or some other flat, stable surface that you plan to use as a workboard. With the pivot pin passing through both the top and the workboard as seen in the following picture, the pin should be stable.

Set your depth of cut by placing an abalone strip on the router base and gradually move the depth stops until the bit is just short of flush with the total depth of the abalone. Then go ahead and plunge the router into the very top of the rosette channel in the upper bout region. Make all of your initial routs in this area since it will be hidden by the fingerboard. When routing, keep in mind grain direction and which side is your waste area. For instance, consult this diagram:

The arrows refer to the direction of routing and the origin of the tails refers to the origin of the rout. Notice that the direction of the rout depends on which side the waste area is on. The general idea is to never cut against the grain and to always ‘push’ the grain down in the direction opposite the waste area. Even if the bit is rotating in the ‘wrong’ direction relative to the cut and leaves a somewhat fuzzy edge, doubling back after cutting in the prescribed direction will fix the problem. These fuzzy edges can also disappear with surface sanding, although be careful not to round the edge of the cavity.

To be on the safe side, make your cuts on the perimeter a few hairs shy of your scribed line and check the fit before cleaning the edge. Scribed lines have a tendency to be a tad too large. Also, making small cuts helps to minimize your chance of tear-out and keeps the edges cleaner than usual. If your final channel is slightly oversized, the purfling will fit nicely when its glued into place, since the water in the glue will cause the purfling to expand slightly. If you can achieve a perfect fit, you can skip the step of gluing the purfling with a water-based glue and instead glue the purfling in place when you glue the abalone.

Check the depth of your channel

to ensure that you did not over-route.

Under-routing is easily fixed by sanding, although tedious sanding can be avoided by routing slightly deeper. If you have over-routed or your depth is uneven, the problem can be fixed by inserting a veneer spacer. Using either a circle cutting tool or a razor blade embedded in a popsicle stick, cut a circle out of veneer and glue it in the channel. If the depth is uneven, rout to the lowest depth and stack as many veneer discs as needed to achieve the proper height.

Before gluing anything, be sure

to seal the area around the rosette as seen below:

I usually use shellac as a sealer, although just about any commercial sealer will do. This will help eliminate glue staining from squeeze-out. The purfling lines should be able to accommodate the rosette channel, but if not, they can be heat bent. After letting the sealer dry, spread a generous amount of glue in the channel and place the purfling rings into the channel, using a Teflon spacer to leave a gap for the purfling. The Teflon spacer is commonly available from luthier supply houses and matches the width of their purfling strips. If not available, you can use a synthetic-based (not an oil based) modeling clay or a similar substance to fill the channel. Be sure and press the filler hard enough to squeeze and accumulated glue out of the channel.

One the glue has had sufficient time to cure, pull the Teflon strip or filler material and inspect the channel for any irregularities. If everything checks out, start planing, scraping, or chiseling the purfling lines flush with the soundboard. Sandpaper is generally too rough and creates too much debris and frayed edges for this task, although it’ll work in a pinch. After getting the purfling lines flush, re-seal the area around the rosette thoroughly.

There are multiple methods for breaking the shell to fit. One is to stick the end of the current strip at work and twist the strip so that a small piece is broken and left into the channel. Another method is to break the strip into somewhat short segments of 10 millimeters or so and then lightly tap them into place with a hammer or mallet. I prefer to use a pair of pliers to nibble off small 2-4 millimeter sections and place them individually,

butting them against the previous piece with a screwdriver.

While this may appear tedious, it only takes about 10-15 minutes to inlay a soundhole. If you use curved strips, the process is about twice as fast or more.

Using abalam instead of abalone

is also a tremendous time saver and the results are often even more attractive. Abalam consists of laminated sheets of abalone veneer, which enables each strip to contain extremely high figure and break evenly and consistency while keeping the cost close to that of standard abalone. As of the time of this writing, a green abalam rosette runs around $15 dollars for straight strips and paua abalam costs about $22. One potential problem with abalam is that there tends to be small voids and bubbles scatted throughout the lines, although these are almost invisible after the gluing stage and can be fixed easily with stick shellac or lacquer.

Once all the pieces are arranged

in a satisfactory manner, start flooding the area with low viscosity superglue. Just about any superglue apart from gels will work.

Try not to get too messy and let the superglue run unto unsealed areas of the soundboard. Since superglue has such a low viscosity, it can easily wick around the gaps in the shell as well as through the purfling. Instead of going around the whole perimeter, work in small 20 millimeter regions and once the initial application wicks through, continue reapplying superglue until the area appears saturated and move onto the next region. If you skipped the purfling gluing step, saturate the purfling as well when applying the superglue. Make sure you perform this task in a well ventilated area and take all the necessary safety precautions. Once the superglue is dry (allow a few hours), proceed to sand the rosette level with the soundboard. If the rosette is a millimeter or higher from the surface, you can use a power sander (not a belt sander) to eliminate some of the grunt work. Once it gets close, switch to hand sanding. Wrap 120 or 150 grit sandpaper around a wooden block and proceed to level the rosette with circular strokes. It is essential that you use a hard backing for the sandpaper so that the wood does not get sanded at a faster rate than the shell. Once the rosette feels flush, step back and admire your handiwork.

Veneer Inlay The basic steps of rosette inlay are pretty much the same, but veneers present some different complications due to the thinness of the veneer. However, due to the wide range of veneers available and the relatively low cost, the rewards greatly outweigh the troubles. For this particular rosette, I’m using a piece of burled walnut veneer that was obtained by purchasing a lot of offcut and odd shapes of veneer. I’d estimate the cost of a veneer rosette to be less than a dollar, even if premium veneers are used. Since this rosette will be installed in a top that will eventually be less than 2 mm thick, the thin rosette will actually be an asset instead of a liability, although even more care must be taken not to scribe any deeper than necessary. One note of caution with figured veneers is to handle with extreme care. Burls in particular can be troublesome due to their erratic figure. A wash coat of shellac can help prevent chipping and tearing, but the best way to cut cleanly and keep the rosettes intact is to use freshly sharpened blades each time you make a cut. With the method of inlay outlined in this guide, edge quality isn’t highly critical, but sharpened blades also help to ensure that you don’t tear the veneer discs apart. With veneers, there’s a wide choice of areas that you can select your rosette from. Use a compass or a template to figure out which section you want to use as your rosette and mark your final selection. Cutting your selection can be accomplished a number of ways, either with a dedicated circle cutter, a blade mounted on a compass, or

the old standby of a blade mounted in a popsicle stick and rotated around a pin. For blades I would suggest using a small skew chisel or knife blade instead of the more common X-acto blades. X-acto blades have a tendency to flex too much and follow the grain instead of cut through it. If you can reinforce the blade though by epoxying a stiffener to the side or only exposing a small section of blade as in the popsicle trick, they perform quite nicely. As in the previous rosette technique, lay out your desired rosette dimensions, keeping in mind that for this style of rosette, the circle needs to be a bit wider to adequately show off the wood’s grain patterns. The following photograph shows a circle cutting tool being used to cut out the rosette from the veneer sheet. It was purchased at a closeout store so I have no idea where to find another one, but similar devices can be found at craft stores.

Cut the outer edge of the circle to be a shade smaller than the overall size of your rosette. Make the first pass very light, scoring the surface but little else, then make progressive cuts deeper and heavier. This will help prevent breakage and chipping. Also be sure to use a sacrificial backing so you don’t cut a series of circles into your work surface.

Scraps of chip or particle board work well for this purpose. After cutting out your rosette disk, keep your cutting radius the same on your jig and make the same cut on the soundboard. Remember to make the first cut a light scoring cut so that the blade follows the line instead of the grain. Once the cut is complete, set up your jig to make the inner cut slightly inside the line as before. Follow the same cutting procedure as before and cut out the rosette ring, repeating the cut on the soundboard. After the lines are marked on the soundboard, use either a sharp chisel or a dremel to clear out the rosette channel. With the dremel, it is not necessary to route all the way to the edge. Leave some material inside then chisel the waste away. The scored lines will make this task easy. The hardest part of this task is getting the depth of the channel right, since your don’t have much room to work with given the thinness of the veneer. In addition, the veneer needs to be just slightly above the surface of the top so that you can get the veneer surface level. If you are uncomfortable with getting the channel depth just right, you can laminate rosette discs. I usually just use a chisel and an abundance of patience, but for the beginner I’d strongly suggest laminating rosette discs as a safety net. Once you have the channel cut, seal the area around the soundhole as before.

In addition, seal the face of the rosette disc. With the use of water-based wood glues, the veneer rosette will do everything it can to curl up and ripple. An alternative is to flood with superglue as with the shell inlay method or use epoxy for glue. Wood glues are still perfectly usable though, albeit with slightly more hassle.

Due to the veneer’s thinness, its almost impossible to get even clamping pressure with a flat, hard object, so I instead use a non oil-based modeling clay as a clamp. Simply press the compound down, forming a ring around the rosette.

This will greatly increase the cure time since now no moisture can evacuate from the front, so after several hours remove the clay and allow another few hours to allow all the moisture to leave before sanding the rosette flush. When sanding, use 220 grit paper by hand and stop immediately once the rosette is flush.

After sanding, proceed to rout the channels for the purfling.

You can find small enough bits from inlay or even dental suppliers. You can also cut the inner and outer lines by hand clear the channel with a dental pick. If possible, try and align your route so that half of the material is removed from the top and the other half is removed from the burl so that any inaccuracies or flexure in the cutting jig won’t result in any unsightly gaps. The burl should now be reinforced since it’s glued to the top, so continue to treat the inside of the rosette as a waste area when determining the proper routing direction. Route slowly though, since the burl is still fragile even in this state.

If you get relatively tall purfling, you can split it in half for this or any other style rosette. Its particularly useful for this rosette due to the thinness of the entire assembly. This can be accomplished either with a sharp knife or a guided jig.

when using this method, make sure the top and bottom are nice and even so that the purfling will have one level side to register with the channel. After resealing the rosette and its surrounding area, proceed to fill the purfling slots with glue and insert the purfling into the channel. Once the glue has set, proceed to scrape, plane, or chisel the purfling lines flush with the soundboard.

It’s a good idea to seal the area around the rosette again as a reminder to keep sanding light around this area when it’s time for final sanding of the soundboard.

Solid Wood Inlay I make the distinction between veneer and solid wood inlay when the rosette material is at least 1/16” thick. At that thickness, the rosette’s workability is closer to that of the other methods so there is much more room for

error than in veneers. The same materials for veneers can be found in solid form, although this will require extensive and careful resawing and surface preparation. If your wood is large enough, you can either cut whole circles or instead saw the stock into tiles like a mosaic rosette. Since my favorite solid wood inlay is spalted maple, its preferable to cut a solid circle instead of tiling in order to preserve the spalt patterning. However, this method generates a large amount of waste. Luckily enough, the leftover discs from the cutting of guitar-sized rosettes are just the right size for bandurrias. I also use circular turning blanks to minimize waste. When resawing blanks, it is easier and often more convenient to split the blank in half then resaw bookmatched disks from the halves. If you don’t want a bookmatched effect you can swap the discs around later. This will require a joint at the bottom end, but with a few deft plane strokes the glue line will be nearly invisible. Since I already had leftover discs from guitar rosettes, my first step was to select the best looking pair.

I use the leftover discs as a source of trim in addition to bandurria rosettes, so I had no bookmatches available. As in the veneer method, the first step is to cut

the outer curves in both the rosette and also the soundboard.

With the thicker rosette material, cutting the circle has some added element of difficulty. Place the pivot point at least 3-4 mm from the edge of the disk and then saturate the pivot and it’s surrounding region with superglue to prevent the pivot from splitting. As with the veneer, make a light scoring pass to provide a path for the blade and make progressively firmer cuts. Due to the weakening from the spalting and the relatively thin sections that are being cut, breakage of the rosette is not uncommon as seen below.

This is not a problem, since the breaks will be practically invisible once the rosette is glued into place as long as care is taken to ensure that the pieces are lined up properly. Numbering the broken pieces helps to make sure you get the arrangement of the pieces correct during assembly.

Excavation of the rosette channel is the same as the other methods, and

can be accomplished with either a chisel or a dremel. Due to the greater rigidity of the material, this rosette can be clamped with a flat, rigid, object and some weights.

If your base object is wood or fiber, wrap it in plastic or waxed paper to prevent the squeeze out from sticking. After the glue has cured, proceed to plane or scrape the rosette flush with the soundboard and then route the channels for the purfling as in the previous method.

Purfling can be split for this rosette too, although I typically have the rosette deep enough to require full strips. The purfling is the glued and then rendered flush as in the veneer inlay.

Soundboard Thicknessing While there are a number of thicknessing methods available, by far the most efficient and effective is the handplane. If nothing else, planing by hand is cleaner and more quiet than any other methods. The softwoods used for tops are also relatively easy woods to plane, making for a good introduction to the use of a hand plane for the beginner. The second most common method of thicknessing is an abrasive planer, or thickness sander. Instead of blades, these devices use coarse grit sandpaper to abrade the wood to the desired thickness. One of the biggest advanatages is that there is no risk of tearout or chipping. Another advanatage is the fine degree of accuracy. In addition, achieving uniform thickness is easy as well. One of the biggest drawbacks is expense, since the units are either hundreds of dollars or require you to build one from scratch. Another issue is dust and noise in addition to the heavy and messy maintenance required. Bladed planers are also common, although these tools are not ideal for most instrument building tools. While thickness sanders don’t cause tearout and a skilled woodworker can sense the grain, most commercial planers are prone to damaging the wood. In

addition, most planers are not designed to take of 0.001” of an inch and are not precise enough to handle the requirements of plate thicknessing. Snipe and uneven blade wear can also cause unacceptable errors. A popular alternative is the Wagner Safe-T-Planer, which uses a bladed disc that chucks into a drill press. The tool rotates in the same plane as the wood’s surface, acting like a large milling bit. However, this tool creates significant milling marks and requires that the drill press be perfectly aligned.

Soundboard Bracing

X-Bracing The X-brace center will be 35 mm from the bottom edge of the soundhole. The center for the secondary X is 76 mm from the center of the primary X-brace center. The finger braces are 61 mm from the center of the Primary X. The soundhole braces are 76 mm from the X brace center along the line of the X-brace. The transverse brace is 15 mm from the top of the soundhole, and the soundhole braces are 25 mm from the center along the edge of the upper transverse brace.

Lattice Bracing While I normally execute lattice bracing with wooden members, for this particular instrument I’m making the switch to carbon-fiber composite and balsa wood in order to both ease fabrication as well as reduce weight. While wooden lattices require lap joints at each intersection, balsa/CF lattices can be constructed with a simplified method. Since the carbon fiber provides the vast majority of the strength and stiffness, the strength of the balsa wood, particularly at the intersections, is much less important than in normal wooden lattices. As a result, this design consists of one long row of continuous balsa with the crossing row comprised of short pieces butt joined at each intersection. One row of carbon fiber is higher than the other in order to allow both rows o cross without requiring a lap joint to be cut.

Balsa wood is readily available from most hobby stores. Once again, since the balsa is mostly there to keep the carbon fiber away from the surface of the top, even the long rows can be made from shorter segments, although construction is easier if continuous strips are used. Carbon fiber composite is slightly harder to find. While you can buy individual carbon fibers, weave them into a lattice, and glue them into place, commercially available unidirectional carbon fiber is typically formed under pressure so that the polymer matrix can permeate through the fibers evenly. Regardless of form, Carbon Fiber is relatively expensive and difficult to find, although there are a number of sources that can be found through the internet. Stewart MacDonald and Luthier’s Mercantile both stock carbon fiber composite, although the selection is fairly limited. The vendor I typically buy from, ACP Composites, stocks a wide range of carbon fiber composite products at reasonable prices. Working with carbon fiber can be quite an ordeal. Recommended tools for cutting carbon fiber are hacksaws, old razor saws, or a dremel outfitted with an abrasive cutoff wheel. Make sure and wear a dust mask whenever you produce dust. Standard wood glues won’t work with carbon fiber, but PVA, CA, or Epoxy will work well. It will also help to rough up the gluing surface of the carbon fiber with coarse sandpaper. Unlike the balsa wood base, carbon fiber strutting must remain continuous throughout its length. The first point of reference in the layout is the main X of the lattice. The center point is 34 mm from the bottom

edge of the soundhole. Using either a protractor or even a precisely folded piece of paper, draw a 45 degree line through the center point, extending past the boundary of the outline followed by another 45 degree line from the other direction. Since the lattice is made of 50 mm squares, the rest of the bracing layout is relatively straightforward. Starting from the center line, mark two points in 50 mm increments on both side of both lines. Finally, draw perpendicular lines from each mark to complete the lattice layout. After laying out the lattice pattern, cut the carbon fiber struts slightly oversized and lay them out to ensure that each brace is accounted for.

Once you have the CF bars cut, proceed to cut the lower row of balsa supports. Larger dovetail saws or bandsaws are typically too aggressive for balsa wood. Razor or hacksaws work nicely and have the added benefit of minimizing waste as well.

The lower tier will run diagonally as shown in this picture, with the stiffness biased in the front of the treble side. Once the balsa struts are cut, sand the radius into the bottom of the braces, starting at 150 and ending at either 600 or 800 grit. The next step is gluing the carbon fiber bars to the balsa braces. The best way to ‘clamp’ the carbon fiber to the balsa is to wrap the assembly with Teflon tape. Since Teflon resists adhesion, it won’t stick to the squeeze-out and make cleanup much more easy.

Teflon has a tendency to bunch up, so wrap straight from the dispenser and proceed slowly. I recommend Epoxy for this task since clamping pressure isn’t as critical as with other glues. If you use superglue, you can apply hand pressure for a few minutes instead of wrapping. Once you have all the composite braces glued together, chisel out any excess glue and sand the sides clean. Also, re-sand the bottom curvature if any excess any glue contaminated the surface. Once you have the surfaces clean, start gluing the braces onto the soundboard. This is most easily accomplished with a go-bar deck and a radiused form.

Make sure that each brace has adequate pressure in both the center and the ends without excessive pressure. Until the composite braces are glued to the top, they will remain fairly flexible and if they are flexed to fit the top, they will exert counterproductive stress to undo the doming once the clamping pressure is taken off. After the first row of braces is glued, the next step is to insert the second row of balsa.

These cross-struts need to be a millimeter or more higher than the first row so that you have sufficient material to level later on. After you cut each strut, sand the radius into the bottom. Since the radius is so slight, mark unradiused tops in case the braces get turned over. Try and keep the butt joints tight if possible. After all the cross-struts are cut, glue each strut into place.

Don’t worry about deforming the balsa, since there should be enough extra material that the indentations will be removed anyway. However, don’t exert so much pressure that you completely crush the fibers. There should be a slight dent but nothing more. After the glue cures, continue to hold the soundboard down to the radius form and either plane or sand the balsa level with the first row of carbon fiber. Balsa doesn’t like to be planed or sanded, but a freshly-sharpened plane blade will make short work of this task, especially if the cutting angle is low. Finally, glue the 2nd row of carbon fiber bars into place.

If there are any gaps in between the 1st row and 2nd row of Carbon Fiber, either fill the gap with epoxy or fit a piece of spruce in the gap. As with clamping the 1st row, apply moderate pressure to the middle and the ends of each brace. Keep the bars under pressure until the full cure time of the adhesives.

Bent Top-Bracing Since this top will be braced without a form on the opposite end, be sure to place cross-grain cauls on the opposite end of the soundboard. These cauls will help prevent the braces from imprinting, or showing through the soundboard. The first braces that have to be glued into place are a pair of longitudinal braces that help maintain the top’s crease as well as provide direct support for the base of the bridge.

These braces are located 30 mm horizontally from the centerline of the soundboard, with about 30 mm of the brace located below the crease line, and 40 mm located above the crease. The braces are 7.5 mm wide, and 4 mm high at the apex.

If your soundboard billet was thicker than 3 millimeters, you can use offcuts for these braces, otherwise, cut these from quartersawn brace stock. You can also laminate soundhole offcuts to achieve the desired height. Using a plane or chisel, cut a 6 degree angle into the brace, aiming for equal thickness on each end, keeping the apex in line with layout requirements. Round the peak of the angle slightly with sandpaper, making sure to work your way up to 600 grit after rounding.

Making sure the soundboard is supported, glue the braces into place.

Cam clamps work well for this purpose due to their long reach, although you can also clamp from the bottom and through the soundhole with C-clamps. The next braces to be added are the two transverse braces on each side of the bridge. These should be cut from quartered stock, 7 mm wide and at least 18 mm tall. The lower brace is positioned 16 mm below the crease and the upper brace is 28 mm above. These braces will fit right over the longitudinal crease braces, so a notch will have to be cut. Position the brace directly over the longitudinal braces and mark their widths. You can either then attempt to cut the notch slightly shorter than the braces and slowly file to the correct depth, or you can cut the notch deliberately deeper and fit a wedge into the gap. I find the latter solution to be much easier and equally effective as the former, although purists and perfectionists would feel otherwise. The notch is most easily cut with the use of a razor saw and a chisel, although a dremel or even a tablesaw would work well too. A miter box is helpful in achieving a perpendicular cut, followed by a small, 1/8” chisel to punch out the waste. Make the cuts for the notch slightly undersized so that a nice,

tight fit will result. Once your notch is cut to satisfaction, proceed to radiusing the brace. The brace needs to be cut to a 6’ radius, so you have a number of options for getting the desired radius. I find planing to a template be the easiest. Developing a template is as simple as fixing a 6’ length of wire to a pivot point and tracing out the desired arc. You can also use CAD software, an arc compass, or the template provided with this guide. If you use the template, use a photocopier or computer to scale the outlines, using calipers or an accurate ruler to ensure that the resulting plot is to the proper scale. Once you have your template, cut out the arc and use it as a tracing for brace profiles. Then, simply plane to the traced line. You can also use the template to construct a guide for a router to automate the process. The guide can then be used to make a radiusing form so that you sand in the profile and have a radiused caul as well. Once the braces are radiused, check the fit to make sure the braces line up properly.

In particular, make sure that the braces make solid contact with the area around the notches. Don’t rely on clamping pressure to seat the braces. If everything fits, proceed to glue the braces.

Due to the large number of clamps involved, glue the transverse braces one at a time. If you opted to cut the notches oversized, install the wedges after the glue cures. Cut long, gradually tapered strip from some bracing offcuts and trim to the width of the notch. Then coat the wedge with glue and firmly push it into the gap. Wait for the glue to dry before sawing off the excess. The next braces to be glued are the bars for the A-brace. These are most easily cut from soundboard offcuts. The target width is 8 mm and the height is 3-4 millimeters, depending on the stiffness of the wood used. For lighter, less stiff woods like Cedar or Englemann Spruce, 4 millimeters is preferable, but 3 millimeters will suffice for Sitka or Red spruce. If your offcuts are not tall enough, laminate two bars together and plane down in order to get the desired height. The center of the A-braces will intersect the upper transverse brace 74 mm horizontally from the center line. Draw a transverse line 10 mm from the top of the soundhole edge. This will also be used for the upper transverse brace as well as A-brace layout. The upper intersection of the A-braces is 28 mm horizontally from the center on the upper transverse line. Line the braces up and cut the required angle for the butt joint with the higher

transverse brace. Once you have the layout set confirmed, proceed to glue the braces down.

While gluing, make sure the butt joint between the bottom of the A-braces and the higher transverse brace remains intact. Like the lower transverse braces, the upper transverse brace under the fingerboard has to be notched in order to accommodate the A-braces.

The procedure is virtually identical to the previous notchings, although the cuts will have to be made freehand instead of mitered due to the angle of the braces. The brace width is 7mm and the height is also around 18 mm, although this will be taken down during profiling. Radius the brace in the same manner as the other transverse braces. Glue the brace in the same manner as well.