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Planning Your Custom Lefty Instument

To avoid hundreds of opportunities to screw up, it is always best to completely plan your instrument’s design in advance. Custom builders like me must absolutely establish total understanding of our customer’s desires before selecting material or cutting a single chip. When working with a custom luthier, it is vital that the customer be very honest in informing their playing skill level and experience tuning and otherwise caring for their instrument. When working with a new customer, I like to use the terms "pickup truck" or "sports car". I take great pride in being able to build very lightweight, flawlessly finished, instruments that respond with perfect pitch to a skilled players pick. However building a very light, highly responsive "sports car" instrument with an adjustable truss rod, custom master grade tuners and a light tailpiece for an inexperienced player is not cost effective. I can and do build very high quality "pickup truck" instruments that are sufficiently rugged to survive the beginner's experiments that can still deliver very high quality sound at a very reasonable cost.

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Except for violins, I build instruments in three grades, Student, Orca and Signature Lefty. The Student grade is made from high quality but less figured woods and fitted with less expensive hardware and limited trim options. The Orca grade is a step up in wood figure, hardware and trim and is generally the choice of cost conscious players who want a fine custom instrument. The Signature Lefty grade instrument is the ultimate in woods, fit, finish and hardware and is equal or superior to an instrument built by any luthier.

For violins, the market is awash with cheap, poorly constructed instruments that are certainly ok for the beginner or casual musician but they neither sound good nor will they last more than a couple of years before falling apart. The violins that I build are carefully crafted to the exact standards of the old Stradivari using wood from the same region. They are meant to last hundreds of years and play better as they mature.

 The information required to build a custom instrument is at a minimum what is shown below:

NOTE: Similar information is required for the larger instruments adjusted for size and tuning.

Instrument Style Fretboard Material
Pick Hand Fretboard Style
Tuning/Sound Style Fret Material
String Break Angle Fret Position Markers
Assembly Glue Fret Side Dots
Rim Block Material String Nut Dimensions and Material
Kerf Lining Material and Style Bridge Design and Material
Point Protector Material Finish Style
Soundboard Material Tuning Machines
Virzi Custom Knobs
Backboard Material Tailpiece
Edge Binding Style and Material Tailpiece Decoration
Neck Design End Pin
Truss Rod Type Pick Guard
Peghead Veneer Strings
Truss Rod Cover Shoulder Strap
Truss Rod Cover Screws Case
Peghead Decoration Display Stand
Passive Acoustic Pickup  

I will take each of these points and expand on the basis of my experience.

Instrument Style 

There are three basic styles of mandolin family instruments, the F, A and bowl back. There are a number of standard variables for each and many more derivative concepts. The F and A styles are built with either a pair of parallel F-holes or a centered oval hole from which the sound emanates. The bowl back style generally has either a round or oval sound hole though one-of-a-kind holes are fairly common. Most F-hole style instruments use a pair of tone bars axial to the sound holes while most centered oval hole instruments use either a single short bar above the hole or crossed tone bars whose axis lies just below the oval hole. The standard mandolin fret scale is 13.875 but lenghts as short as 12.50 or long as 15.00 are regularly built. The same basic body styles and structural configuration hold true for the larger mandola and mandocello that can have scale lengths of from 15.50 to 25.0 inches.

Guitars come in three basic form factors flat top, archtop and solid body. Most flat top guitars, except for the Flamenco, actually have a top radius of from 12 to 20 feet to add a bit of stiffenss and raise the level of the bridge to minimize the bending load on the saddle. Acoustic guitars are built with both symmetric upper bout and cutaway comfigurations. Due to their large size, weight is a more significant factor and should be given proper consideration. Solid Body guitars can be in any form factor since the electronics determine the sound. They are regularly built as 6-string standard and 4-string bass. The parler and plectrum guitars are smaller versions of the acoustic guitar. The plectrum has 4 strings rather then 6. These smaller body guitars are ideal for younger players if constructed with a slightly narrower fretboard.

Ukuleles are basically small 4-string guitars and are constructed using the same processes but their soundboards are usually built from mahogany or koa rather than spruce.

Pick Hand 

Most years half of my instruments are built for players who hold the pick in their right hand and fret the strings with their left hand. Many left-handed individuals have trained themselves to play in this manner but for some, including me, holding the pick in the left hand is preferred. I am dedicated to building instruments for the true lefty.  Virtually all left-handed mandolins are custom built for a particular customer though I occasionally see one from a volume builder. On rare occasions you see a standard guitar modified for left handed play with the glue on pick guard upside down. Looks like crap. The notable exception to this is the Epiphone 1964 Texas guitar made famous by Paul McCartney that was played upside down. Many fans still request this odd looking modification.

Tuning/Sound Style 

There are three basic sound styles for the mandolin family of instruments; Bluegrass, Mellow and Bass Emphasis. The Bluegrasss style creates a bright treble emphasis with relatively low sustain that permits a clean chop; Mellow style creates a balanced acoustic response with increased sustain and the Bass Emphasis creates a powerful bass response with lots of sustain. Regardless of sound style, all mandolins are tuned G3-D4-A4-E5 as is the violin. To compliment this tuning pattern, the backboard is tuned to C3, the treble tone bar to A#3, the bass tone bar to G#3 and the air chamber to D#3 with A on the frequency scale set to 440 Hz. On A style oval hole mandolins, the soundboard is tuned A#3 when tapped just below the soundhole. When a sound quality similar to the older Gibson’s is desired, the frequency scale is set to A 430 Hz and very light strings are used. To achieve the unique sound styles, the top profiles are adjusted for both top contour and deflection. Tuning can be achieved with two unique methods:

  1. Thin the soundboard to structural minimums with emphasis on the recurve area to a resonant frequency below G#2 then add tone bar stiffness to raise the resonance to the desired frequency.
  2. Use standard soundboard profiling, which usually results in a higher than desired resonant frequency, and add mass on the bass and treble sides to lower resonance to the desired frequency.

If you desire a bright sound with sharp bark for Bluegrass, option 1 is preferable, providing the soundboard wood is flawless. If you desire a balanced mellow tone or your soundboard wood is less than master grade, then option 2 is best. In either case this is not as difficult as one would think. The bass response sound style however, requires a substantial change in top contour and string break angle. Most of the mass of the tone bars is in their center but Spruce tone bars are very stiff so if their ends extend over the recurve it is relatively easy to raise the resonant frequency by thinning the center to minimize mass but leaving the ends relatively thick to add stiffness. And conversely trimming the tone bar ends clear of the recurve and then carefully thinning the center will lower the resonant frequency. Similar tuning formats are used on the other archtop instruments.

In all cases, the backboard of archtop instruments is adjusted by a combination of thinning the recurve and center to lower the resonant frequency. It is impossible to raise the resonant frequency of the backboard without compromising its’ visual beauty so one must proceed with caution when making final adjustments after installation on the rim. The bowl back style is tuned similar to the guitar.

I generally use method 1 when the soundboard material is Red, Russian or Carpathian Spruce and method 2 when using Sitka or Englemann Spruce or Alaskan Yellow Cedar. Under no circumstances should method 1 be used for Western Red Cedar or Redwood due to their tendency to split along grain lines.

 Flat top guitars with cross bracing are generally tuned with each top of the X brace at G and the lower part of the X to F. The Flamenco and classical guitars, which are fan braced, generally have the treble side set to F# and the bass side set to C#.  With appropriate adjustnents to both tone bars, bracing and strings, significant effects on timbre can be created. I can create emphasis for classical, bluegrass, flamenco or country western music depending on the customer's desire.

For solid body guitars, there are literally hundreds of pickup and wiring configurations to choose from. Depending on your style of music, visual wishes and amplifier selection, anything is possible. The only things critical are perfect fret postion and level, precise alignment of sensors and strings and convenient placement of the adjusting knobs.

String Break Angle 

The combined tension of 8 strings tuned to pitch for a standard 13.875 inch mandolin scale is between 160 and 180 pounds. From a structural point of view, the downward force on the soundboard should not exceed 50 pounds. For a light string set having 160 pounds of combined tension at pitch, the string break angle should be 18 degrees whereas for medium-heavy strings having 180 pounds of tension, the string break angle should be 16 degrees. For the bass emphasis sound style, where heavy strings are used, the string break angle shold be between 12 and 16 degrees. A happy medium for most players is 17 degrees but under no circumstances should it exceed 20 degrees without making design changes to the soundboard. The archtop guitar and mandocello, due to their larger size and longer scale length, have string break angles of from 12 to 14 degrees.

Assembly Glue 

Sounds trite but the decision to use either the traditional hot hide glue or the modern Titebond I adhesive is a major issue. Hot hide glue makes a very strong bond when properly applied but can be a disaster if not done correctly. Titebond adhesive is nearly idiot proof in application but suffers from a serious shortcoming should major repairs be required at some future date. Either glue will make a joint stronger than the parent wood. One notable caveat is that with oily woods such as Rosewood or Cocobolo, the joint surfaces should be thoroughly cleaned with acetone before applying either adhesive.

When using hot hide glue, the joined pieces must be perfectly fit to each other with absolutely no gaps in the joint since the primary attaching force is capillary action. In addition both pieces of wood and the glue must be warm, very warm, to assure a sound bond. Attempting to use hot hide glue in cold weather is very risky, even for experienced woodworkers. When I make a hot hide glue joint, I warm the wood with a heat gun or leave it in the sun for an hour first, then liberally apply properly thinned glue (warmed to 145 F) to both pieces, rub them together vigorously until I feel resistance, then clamp the joint.

When using Titebond I, it is still best to get a perfect fit but small voids have little effect on bond strength. Just slap on a liberal amount of glue, rub the joint to assure even distribution and clamp. In 40 minutes, remove the clamps and clean off the excess with a sharp scraper or chisel.

Hot hide glue joints can be softened with heat so a joint can be reopened for major repairs. Hot hide glue also can be stained over. Titebond joints are more permanent; while heat above 150 F will degrade the adhesive to some degree (and possibly melt the binding), the easiest way to separate two Titebond glued pieces is with a saw. Titebond also seals the wood so if a drip is not completely removed down to raw wood, stain will not penetrate and neither will lacquer or shellac. If one leaves an instrument inside a car on a very hot day, either glue can fail with disasterous results. Hide glue is also very sensitive to moisture penetration so must be protected from dampness.

My standard practice is to use Titebond I to join the soundboard and backboard halves, the rim components and kerfed lining unless the customer specifies only hot hide glue. I always use hot hide glue to attach the neck, and fretboard since they are most likely to be removed for future repair/replacement. Depending on the specific order I use either glue to attach the soundboard and backboard to the rim. Since hot hide glue requires significantly more prep time, I charge extra to cover the extra labor. My violins are fully constructed with hot hide glue since over a long lifetime it is certain that they will require repairs.

Rim Block Material 

The rim blocks are structural elements, in particular the head and tail blocks. Traditional woods are Mahogany or Maple though in a minimum weight instrument, Spruce or Spanish Cedar can be used for the head block and points. The early Gibson mandolins had Mahogany head blocks cut on a 30-degree grain angle to minimize splitting around the dovetail mortise.

On my instruments, I laminate two pieces of Mahogany or Maple with the grain oriented 90 degrees to each other and then cut the head block on the traditional 30-degree angle. On F5 mandolins I generally use Indian Rosewood for the tail block both for its’ strength and weight since the peghead’s weight generally causes the instrument to be neck heavy and this helps with balance.

The point blocks for F5’s can be made from any wood but most are cut from the same blank as the head block out of convenience. I regularly use Spruce scraps for the point blocks simply as a way to reduce weight.

On flat top guitars I use Maple, Mahogany or Spanish Cedar necks in the spanish construction style where the neck extends into the body around which the rest of the instrument is constructed. On special order, I will use either a dovetail or bolt on neck joint. Since the guitar neck is a significant percentage of the instrument's weight, it must be given consideration. Maple, Mahogany and Spanish Cedar, in that order are from heavy to light at equivalent strength. The same for the rim and back where Rosewood is heavier than Maple.

The Flamenco guitar is a bit different since it must be very light. It normally has a Mediterranean Cypress rim and back and demands a very lightweight neck of either Spanish Cedar or Cypress.

Kerf Lining and Style 

The purpose of the kerf lining is to provide a suitable gluing surface between the rim and the soundboard and backboard. The traditional kerf lining is a notched triangular strip of Basswood with the thin membrane glued to the rim. Another style is dubbed reverse kerf where a square strip of Basswood is notched and then the notched side is glued to the rim. The benefit of the traditional kerf lining is minimum weight but it suffers from being quite fragile during leveling and gluing. It is very easy to knock off some of the tiny notched pieces. The benefit of the reverse kerf is that it protects the fragile notched pieces but adds nearly twice the weight to the piece.

The third and most rugged style is to successively laminate three 0.040 thick strips of Maple together while bent around the rim and to then trim the underside into a triangular form factor. This style is used on many guitars and larger arch-topped instruments such as the mandocello and is perfectly satisfactory for the mandolin though a bit heavy.

I have tried all three styles and tend to use the traditional kerf lining (except on the flamenco guitar top) by exercising extreme care during assembly. This style provides adequate gluing surface, minimum weight and frankly looks more elegant than the others. The flamenco guitar requires a far wider glue surface due to the extremely thin top so wide triangular pieces of Spruce or Basswood are individually glued in place.

Point Protector Material 

Any solid material that accepts glue can be used as point protectors on the F5 mandolin. The two materials most commonly used are bone and white ABS plastic. Other materials sometimes used include PVC plastic, Ebony, ivory celluloid and fossil ivory. There are no major benefits or problems with any of these materials, it is primarily a matter of choice to fit overall décor. I tend to use composite ivory or white PVC plastic, since they both are very easy to shape and polish while being quite resistant to bumps. If you choose celluloid for points, one must be very careful with a heat gun when fitting the binding since the thin edge of the point will easily catch fire. One caution with bone; it is porous and will absorb stain through the tiniest masking tape leak. Stained bone is generally impossible to return to pure color. Ivory is both strong and non-porous and adds a touch of elegance if cost is not the primary consideration.

Soundboard Material 

The soundboard is the key to great sound and its’ selection is the singular most important decision made in constructing an arch-topped instrument. In my opinion, Alaskan Yellow Cedar/Canadian Cypress and Carpathian Spruce make the finest soundboards acoustically. Adirondack (Red) Spruce and Englemann Spruce are the traditional soundboard woods and they are excellent though Sitka Spruce and Russian Spruce have equally good, though somewhat different, sound qualities. From the visual aspect, one can’t beat Alaskan Yellow Cedar or Englemann Spruce, which range from pure white to light cream in color.  The spruces occasionally have a wavy character know as "Bear Claw", which is sometimes requested by a customer. I personally do not like the appearance but will use it if asked. The one area where Russian Spruce excels above the others is for a very lightweight archtop instrument tuned for a sharp Bluegrass bark. This wood, when  properly selected, has the greatest strength to weight ratio and thus can be thinned to amazing levels for very precise tuning and string excitation response.

Soundboards can be made from Western Red Cedar and Redwood but they are very split prone so extreme care must be exercised in selecting wood and during fabrication to avoid splits. Even a very tiny nick or grain waver may split under load. Cedar is regularly used for Classical flat top guitars.

If one is planning a blond finish instrument, you can’t beat Alaskan Yellow Cedar or Englemann Spruce. If selecting the classic Cremona Sunburst color scheme Carpathian Spruce is my wood of choice rather than Red Spruce since it tends to need less dedamping time to reach acoustic maturity though it is difficult to tell them apart visually.  If an opaque finish is selected, Sitka Spruce is an excellent choice since it is less expensive and perfectly adequate acoustically.

More important than wood species is selecting wood that has been either hand split or pie sawed from the log and has very uniform growth rings with more than 14 rings per inch. I seldom use soundboard wood with less than 24 rings per inch. Quarter sawing is sometimes ok but I avoid this type of wood unless it is hand selected. Under no circumstances will I use slab-sawn wood for a soundboard.

Virzi 

The Virzi is perhaps the most misunderstood component used on the mandolin family. This small wood disk is suspended below the soundboard between the tone bars with intent to help produce higher frequency partials. The Virzi is held near its’ center rather than along the edges so that the perimeter is free to vibrate. In the mandolin, the Virzi’s value is somewhat questionable due to the tradeoff between weight added to the soundboard versus the improvement in high frequency partials. I always use a Virzi on mandolas and mandocellos.

If a Virzi is used, longitudinal grain Spruce or Yellow Cedar is best, rather than the vertical grain used in the soundboard, and thin it to a thickness of not more than 0.080. The uniformity of this thickness, the precision of the two F-holes and method of mounting all play major roles in its’ performance. It is essential that the Virzi mounts not be in contact with the tone bars since to do so will alter their resonant frequency significantly.

Backboard Material 

Any hardwood can be used for a backboard but Maple and Walnut are usually the woods of choice for archtop instruments due to a combination of visual beauty and dimensional stability. Rosewood is  preferred for fine guitars and will also work on a small instrument like the mandolin but it is difficult to reduce the recurve thickness to a point where the resonant frequency is sufficiently low without making it very fragile. Honduras Mahogany and European Cypress also make acceptable flat top guitar backs though I do not think they are as elegant as Rosewood. Many Flamenco guitar customers specify the Cypress back for a more tradidional look. There are many other exotic woods that can be used on guitar backs that each have both good and bad points. I have used Cocobolo, Satinwood, Blackwood, Bubinga and Mesquite with good results but do so only when specified by the customer after a great amount of discussion.

My first choice for archtop backs is Red Maple; it is readily available as both Birdseye and Curly. Red Maple is very hard and has closed pores so it can be sanded to a mirror surface. Western Bigleaf and European Maple are other species used. I do not like them as well as Red Maple due to a more stringy texture but they do finish well.

Black Walnut from East Texas or Arkansas and Brazilian Rosewood are the ultimate in dark beauty. Walnut has a bit more internal damping than Maple but still makes exceptional backboards and superior necks and it is impossible to beat Rosewood for guitar backs. Dimensional stability is what makes Walnut the wood of choice for quality gunstocks and this characteristic is valuable for mandolin necks. It is essential that pore filler be used before applying finish to both Rosewood and Walnut. Burl or Curly Black Walnut finished with French Polish has exceptional beauty and seems to have three-dimensional characteristics.

Edge Binding Style and Material 

Binding the edges of the air chamber, fretboard and peghead has become standard for quality mandolins. There are basically seven binding styles:

  1. Solid color plastic strip 0.060 to 0.090 thick and 0.25 high.
  2. Vertically laminated multi-color plastic strips 0.040-0.020-0.030 thick and 0.25 high.
  3. Horizontally laminated multi-color plastic strips 0.250-0.020-0.020 in height and 0.060 thick.
  4. Combination of vertically and horizontally laminated multi-color strips.
  5. Solid hardwood wood strips usually between 0.040 and 0.080 thick and 0.30 high.
  6. Multi-piece hardwood or fiber strips usually between 0.040 and 0.080 thick and 0.30 high.
  7. Abalone or Pearl perfling with any of the other bindings.

Most plastic edge binding is either ABS plastic or celluloid. Since celluloid is designated a fire hazard material, it is costly to ship and thus is less used by volume builders but many if not most custom builders prefer celluloid.

Both ABS and celluloid will dissolve in acetone so it is very easy to bond pieces together. Many Luthiers use a “mud” made of scraps dissolved in acetone as a filler or cement. Both materials are heat sensitive and can be easily bent after being warmed. Both will burn if heated too hot.

I prefer celluloid on the mandolin family both for the traditional visual effects and the fact that it laminates better than ABS. ABS tends to melt together and blur the color boundaries when laminated whereas this is not a problem with celluloid. I prefer wood on guitars since the more gentle curves make it easy to use and adds a more traditional look.

Due to greater difficulty in bending around tight curves, wood bindings are typically only used on A-style instruments and guitars though some highly skilled Luthiers do use wood bindings and purflings in elaborate patterns on F-style instruments. Fiber multi-piece bindings and purflings are a bit easier to bend but it is a major challenge to match the pattern at points of intersection. Thousands of multi-piece wood and fiber bindings are available commercially and many Luthiers make their own unique strips though it is very time consuming.

Regardless of binding material, it is best to cut the channel a bit oversize in both height and thickness so that any cement that squeezd out can be sanded away without altering the binding itself.

Neck Design 

The instrument neck is very complex. It is both a major structural component and a precise platform for the fretboard, string nut and tuning machines. On the smaller archtop instruments, the neck is joined to the air chamber mortise with either a dovetail or open V tenon. The dovetail tenon used on archtop instruments is cut on a downward angle of between 4 and 6 degrees depending on the desired string break angle. The peghead section is cut at a downward angle between 12 and 13 degrees. On flat top guitars the neck angle is usually from 0 to 2.0 degrees depending on soundboard design.

The dovetail tenon can be either straight or V in form. The straight tenon is somewhat easier to cut and fit to the mortise than the V but due to being thicker at the bottom end there is less structural wood in the headblock to resist the bending force of string tension. Having a sufficiently large backboard heel button glued to the neck base mitigates this structural issue. Either joint is perfectly adequate structurally though many Luthiers take great pride in being able to cut a precise tapered dovetail tenon.

The open V tenon neck is secured to the headblock by inserting 5/16 dowels in holes drilled on either side so that half of the hole is in the neck heel and the other half in the headblock. This process is perfectly adequate structurally but suffers from two major disadvantages:

  1. The neck must be secured to the rim before the backboard is attached. This makes it very difficult to cut the binding notch on either side of the neck.
  2. If repairs are required in the future, the back must be removed before the neck, this really screws up the finish and binding.

The shape of the neck is a major factor in the playability of the instrument. There are an infinite variety of contours in use but they can be boiled down to three basic shapes; C, Oval and V. The C-shaped neck is generally used on larger stringed instruments such as guitars where the fretboard is wide and more difficult to span with the hand. The Oval shape is a progression of gentle curves that get wider and deeper up the neck. The V shape is an exaggeration of the Oval with a sharper bottom to the curve.

On the mandolin, the C-shaped neck must be very carefully cut to provide sufficient strength while maintaining the desired contour. I do not recommend this shape on any instrument but the mandocello and guitars.

The Oval in its’ many manifestations is the best for most players. It combines adequate sectional area to resist bending with finger comfort.

The V-shaped neck is desirable for players who use the center point as a thumb reference when playing. It also provides more dramatic display of a finely figured wood.

Peghead shape is essentially whatever the builder desires providing there is sufficient space and clearance for the tuning machines. Generally the total peghead thickness should be between 0.475 and 0.550 with both surfaces parallel. Generally when top and bottom veneers are to be used, the 0.475 thickness is required to assure sufficient exposure of the tuning pegs. On the F-style instruments and some others, the peghead shape is cut while holding the fretboard plane parallel to the saw surface with the use of a suitable fixture. On many A-style instruments the peghead shape is cut perpendicular to the top surface to simplify binding installation and reduce finish time.

On F-style instruments the scroll boundary must be reinforced to prevent being broken off inadvertently if the instrument is bumped. Some builders inlay a disk of wood with the grain running perpendicular to the peghead. I generally use a thin piece of Maple whose grain runs perpendicular to the neck grain sandwiched between the parent neck and top veneer. On special order I will install a 3/16 diameter brass rod or maple dowel transversely through the narrow margin.

Truss Rod Type 

The neck is subjected to the continuous string tension, usually between 160 and 240 pounds. Over time, that load can deform the neck to the point that the frets no longer are in a straight line, making playing difficult or impossible. To resist this continuous force, a very rigid rod of some sort is implanted in the neck. There are two basic types of reinforcement normally used:

  1. Steel truss rods having an adjustment screw buried in the peghead.
  2. Carbon fiber or steel beams bedded in the neck with epoxy.

There are three styles of steel truss rods in common use:

  1. A straight 3/16-diameter rod connecting a 3/8 round block in the upper neck to a sturdy washer/nut combination in a slot cut into the peghead.
  2. A similar rod that is curved from high at the tenon to low in the middle to straight into the peghead slot.
  3. A double rod that has one fixed and one adjustable.

All three types must be housed in a plastic sleeve that permits the rod to slide when adjusted and are usually covered by a spline of wood matching the neck. By adjusting the rod’s tension, the neck is preloaded and in the case of types 2 and 3 cause the neck to bow upward in the center to counteract the bending load of the strings. This allows the Luthier to fine tune the fret/string clearances.

The carbon fiber spline or steel beam is rigidly bedded into the neck and acts as a very strong stiffener. A 0.125 x 0.500 carbon fiber spline that is properly bedded with epoxy will resist more than 300 pounds of bending force or far more than the dovetail mortise/tenon joint can withstand. When the neck is finished straight and flat the fretboard will be perfectly stable for the life of the instrument. The down side, if it is considered one, is that no adjustment in neck arch is possible. What you get at first is what you have for the life of the instrument.

The adjustable truss rod has a second benefit compared to the spline; by preloading the neck, string vibrations are more easily transmitted to the air chamber and sustain is generally increased. The down side of the truss rod is that a significant portion of the peghead is taken up by the nut slot and cover plate. The carbon fiber spline is completely buried beneath the veneer offering the opportunity to use far more elaborate inlays.

I personally have no preference and leave it up to the customer to decide which they desire. On lower cost instruments and those for beginners, I tend to suggest the spline since it protects the neck from eager souls who can over-tighten the truss rod nut and either strip the threads or even worse, break the truss rod.

Peghead Veneer 

Peghead veneer serves two purposes, one partly structural and one totally cosmetic. It is essential that a top veneer be used on the F-style instruments and helpful on all others.

Most neck blanks are no more than 2 inches in width and most pegheads are far wider so wings of matching wood are normally glued on either side of the parent neck wood. It is nearly impossible to closely match the grain and pattern of the parent wood so the top veneer serves to hide this mismatch. On F-style mandolins many builders use a disk of wood with the grain perpendicular to the peghead’s grain to reinforce the narrow section of the scroll. This unsightly fix virtually demands being covered. The top veneer also is a palate for decorative inlays that greatly enhance the visual appeal of the instrument. Most Luthiers also inlay either their name of brand identification.

On the finer custom instruments a bottom veneer is also used, which serves both to enhance the appearance and provide a very flat surface for the tuning machine bases.

Any hardwood can be used as peghead veneer but the most popular is Gabon Ebony. The solid black color makes it very easy to hide any voids around inlays and the hard surface can be easily sanded to a mirror finish. Rosewood also makes excellent veneers but it is very difficult to color match filler around complex inlays due to the striped character of Rosewood. For those who like brighter colors, dyed Pear wood, Curly Maple, Cocobolo, Koa and Padauk make exceptional veneers; they are usually custom made by the Luthier whereas Ebony and Rosewood veneers are readily available from most supply houses.

Truss Rod Cover 

When a truss rod is installed, a cover must be placed over the nut cavity in the peghead. The less expensive instruments generally use a black plastic cover or one that is black with a white border. These work fine to hide the hole but add nothing to overall décor. On many more expensive custom instruments the cover is made from an exotic wood, abalone or pearl shell. Many of these are engraved with the builder or owner’s name or some image.

I have made covers from things such as 14 karat gold, every sort of exotic wood, every kind of mollusk shell to fossil ivory. The most unique cover that I have made was constructed from a piece of Ebony scrap from the peghead that had a spring clip bonded on the back that slipped under the end of the truss rod. This cover fitted flush and was virtually invisible at first glance but was easily removed with a push of the thumb. It was not inexpensive though.

Truss Rod Cover Screws 

Usually either two or three screws are used to secure the cover in place. On most instruments the screws are round head and finished to match the tuning machines, either nickel or gold. Some use black lacquer to blend flat head screw heads into the color of an Ebony peghead veneer so that they are not noticeable.

The option of two or three screws is not trivial. On many instruments the truss rod lies too near the top surface of the peghead for sufficient screw length penetration so the on centerline two-screw option is not feasible.

Peghead Decoration 

Decorating the peghead with inlays is nearly universal on F-style mandolins and common on A-style. Generally the inlay is, as a minimum, the builder’s name or logo. From there inlays can be either a simple shape such as a star or flowerpot to complex highly artistic figures; the sky is the limit. Most inlays are some sort of mollusk shell or reconstituted stone set into a carefully excavated cavity. This is one place where the skill of the Luthier is evident. Perfectly cut inlays set into close fitting cavities is the true mark of a master. If the peghead is made from Ebony, a multitude of sins can be disguised with a paste of epoxy filled with fine Ebony sander dust that after curing is sanded flush. This type of repair is fairly well hidden if the peghead is finished with lacquer but differences in material may still be visible with either an oil or spirit varnish finish.

My favorite inlays, other then the Lefty Luthier logo, is the waving grass or pot and vine patterns done in highly figured pearl. I developed these patterns over the years based on personal taste and approval by many customers. By using a very tiny end-cutting bit in a CNC milling machine, I can make the cavities so precise that no margin filler is necessary providing no splits in the veneer happen. Evidence of this precision is retaining the parent wood in the center of the e’s in the Lefty Luthier logo. The cost of elaborate inlays can easily match the total material cost for the average mandolin.

Acoustic Pickup

Should you wish a acoustic pickup, the most effective ones are the piezoelectric type that are bonded to the inside of the soundboard with the output to the amplifier through a standard jack in place of the end pin. There is insufficient room for larger ones on mandolins though mandocellos and archtop guitars could be fitted with a humbucker style. I use and recommend the K&K brand of passive pickup but others will also work. For guitars, there are several types of pickup that have a tiny piezo sensor under each string and in one case have individual output adjustments through a preamp.  In all cases, it is desirable to order the pickup when the instrumet is being built since proper bonding is critical and it is quite difficult to properly install them once the instrument is complete. Solid Body guitars sound best when fitted with bridge and neck humbuckers.

Fretboard Material 

The fretboard or fingerboard as some call it is where precision is paramount. If the frets are not precisely located even the best instrument will sound terrible. This level of precision is very difficult in anything but very hard wood that cuts clean slots. Gabon Ebony, Indian Rosewood and Cocobolo are all suitable as is unfigured Maple. Each wood has both benefits and drawbacks:

  1. Gabon Ebony is the hardest and heaviest wood and is very brittle, which makes for clean slot cuts but is also the easiest to chip off an edge. Ebony polishes to a mirror finish that can be easily restored by buffing with 0000 steel wool and rubbing on either linseed oil or paraffin.
  2. Indian Rosewood is nearly as hard as Ebony and due to its’ natural oils is very durable. It is also less expensive than Ebony so if cost is an issue, it is a good choice. The down side of Rosewood, in my opinion, is its’ rather mundane figure and due to the internal oil it never really shines like Ebony.
  3. Cocobolo is similar to Rosewood in material characteristics but has considerably more figure. It makes a beautiful fretboard.
  4. Maple, while not as hard as the other three is one tough wood as proved by the thousands of Fender guitars. It is also far less expensive than the other three woods. If a light colored fretboard is desired, a flawless piece of Maple is the wood of choice. The downside is that Maple must be protected with varnish, epoxy or lacquer in order to stay looking good. Eventually this will require remedial service whereas the other woods will look great for the life of the mandolin.

Fretboard Style 

There are as many styles of fretboard as there are builders, but three patterns seem to be most common. On The A-style a square end is most common on low cost instruments that do not have binding while some sort of bulge in the end is most common on the more expensive instruments that have binding. On the F-style instruments the most common is the protruding finger design that originated with Gibson. Nearly as popular is a shortened finger style with either a sharp or rounded upper boundary.

Virtually all F-style fretboards are bound. Though probably half of the A-styles are not in order to keep cost down. Probably less than one quarter of flattop guitar fretboards are bound though far more archtop ones are.

On fretboard styles whose upper end extends over the soundboard, most are scooped to minimize pick strikes. This feature also adds a bit of class to the fretboard.

Fret Material 

Fret wire comes in a wide variety of sizes and three standard materials. 1. Nickel Silver (a Copper alloy). 2. EVO Gold is similar in composition to Nickel Silver but Gold color throughout. 3. Stainless Steel.

Nickel Silver is the industry standard and comes in a wide variety of sizes from a number of manufacturers. It bends and polishes easily. It is relatively easy to form for arched fretboards and press into the grooves. It also is easily leveled with standard leveling files or a diamond sharpening stone. EVO Gold is a bit harder than Nickel Silver but otherwise identical save for its’ color. The major negative is that these materials are relatively soft and will eventually groove from the pressure and vibration of fretting the strings.

Stainless Steel is extremely hard and very stiff, making it both far more durable and more difficult to install. It is also nearly impossible to level with standard leveling files so extreme fretboard contour and installation precision is required and thus is more expensive.

Fret Position Markers 

On fretboards it is standard procedure to put some sort of surface marker between frets 4-5, 6-7, 9-10, a double marker between frets 11-12 and a marker between frets 14-15. For many years the standard has been 0.25 diameter pearl dots though any sort of marker can be used, some very elaborate. Recently, I have been creating lighted markers that are quite impressive when viewed on a dark stage as well as enabling easy viewing of fret location.

Fret Side Dots 

Generally smaller markers are put on the fretboard binding in a color contrasting with the binding. For white or ivory binding, black ABS plastic or dark abalone are normally used and on black binding pearl or white ABS plastic. I have also seen pieces of galvanized wire used but to me that is cheap. On my more expensive instruments I use 2.5-millimeter diameter diamond faceted zircons or synthetic rubies and once real diamonds.

String Nut Dimensions and Material 

The nut is traditionally made from either bone or pearl but various other materials are used including Corian, marble, ivory and several types of synthetics. Of the various synthetics, TUSQ or composite ivory is by far the most popular and are, in fact, pretty good materials. I prefer pearl or ivory on mandolins and bone or ivory on the larger mandola, mandocello and guitars.

On the mandolin, string spacing ranges from a maximum of 1.250 to a minimum of 0.900 with 1.050 being the most common outer G to outer E. My personal preference is 1.00. The mandola and mandocello usually have string spacing from 1.20 to 1.50. Most guitars have spacing from 1.375 to 2.25 with the wider nut more common on Classical and Flamenco instruments. My experience is that playability is improved with the narrowest nut one's fingers can handle since that makes it easy to span with the little finger for more complex chords.

Bridge Design and Material 

There are dozens of bridge designs for archtop instruments but they all fall into two categories, fixed and adjustable. The most popular bridge materials are Ebony and Rosewood for adjustable bridges and Maple and Ebony for fixed ones. The other major variable is the saddle or string contact material, which varies from the parent wood to bone, metal, ivory, etc. There are minor acoustic effect differences between the different saddle materials with Ebony and Rosewood generating good balance between bass and treble frequencies. Bone and ivory generally slightly enhance treble response due to being harder materials.

There are two general types of adjustable bridge; the Gibson style that uses two posts with small flat nuts to support the saddle and the Brekke style that uses two small Ebony wedges driven by set screws to raise or lower both sides of the saddle individually.

My personal favorite design is a very lightweight Ebony Gibson style adjustable bridge for mandolins tuned for bluegrass music and a similar bridge having a larger foot over the bass tone bar when a Virzi is installed. On mandolas and mandocellos I generally use a fixed Maple or Ebony bridge with either bone or ivory string contacts. My favorite fixed bridge design is that developed by Red Henry. This design greatly enhances acoustic output and, when properly adjusted, provides excellent frequency balance.

On flat top guitars any hardwood is acceptable for a bridge, usually selected to match the fretboard with a bone saddle. Steel string bridges use tapered pins in holes bored through the soundboard to secure the strings while nylon string bridges generally use knots looped through holes bored through the back of the bridge.

Finish Style 

There are an infinite variety of finish styles but they can all be condensed into three categories; plain, stained and painted.

When using highly figured backboard and neck wood and a perfectly even colored soundboard finishing with clear shellac, lacquer or varnish is perfectly acceptable and is nearly always used on guitars. The classic finish for F5 mandolins is the Cremona Sunburst where a yellow base stain is over coated with a progressively darker stain around the edges. The other basic style is to use a powerful oxidizer like potassium dichromate to darken the underlying grain, sand or scrape off the top surface leaving only the very deep figure darkened and then using a light colored shellac or lacquer coat. The other finish style is to use an opaque varnish or lacquer. The major problem with opaque finishes is that every tiny blemish stands out so an inordinate amount of final filling and sanding is required for an acceptable job.

Coatings normally used on stringed instruments are sprayed lacquer, spirit varnish (flake shellac dissolved in alcohol) applied in the French polish manner and brushed on oil varnish. All three coatings will create a flawless mirror finish when properly applied. I generally use water clear acrylic lacquer since it is less prone to spidering cracks than nitrocellous lacquer. Blond shellac dissolved in grain alcohol makes both a fine final finish as well as a good seal coat for stained wood. There are dozens of excellent oil varnishes available; the one that I normally use is an alkyd oil varnish with tung oil specifically made for acoustic instruments.

The positive for lacquer is that it is easily sprayed, dries quickly and can be sanded flat and then buffed to a mirror finish with little difficulty and is quite resistant to sweat and scratches. French polish is a very time consuming technique that is nearly foolproof and provides a very thin acoustically responsive finish. Oil varnish is quickly applied and is easy to achieve a very uniform coating and continues to improve with age. Hand rubbed oil finishes such as Tru-Oil or linseed oil can be used but do not provide the same level of percieved quality though they are quite durable.

The negative for lacquer is that it can craze due to rapid changes in temperature or humidity. French polish applied shellac is very fragile and easy to abrade and scratch. Oil varnish takes weeks to fully cure and is very prone to dust contamination. Once cured it is a very long lasting finish.

My personal preference is acrylic lacquer that has been carefully wet sanded level with progressive grits starting with 600 – 1200 – 2000 – 4000 – 6000 and then buffed with a very fine pumice and oil. Either a high gloss or more satin finish can be created depending on how final buffing is performed. On flamenco guitars and violins, only oil varnish is used unless specified otherwise by the customer.

Tuning Machines 

There are three levels of tuning machines used on stringed instruments. Asian junk, well constructed commercial grade and master craftsman grade made to order.

The only reason one would ever use the Asian junk is on a beater not fit for any other type. I personally will have nothing to do with this grade of tuning machine when building a custom instrument.

Grover, Schaller and Gotoh make excellent commercial grade tuning machines. They come in either bright nickel or gold plated finish and usually with metal or molded plastic knobs in either ivory or black color. Other than a small amount of gear backlash, they are functionally equal to the finest custom tuning machines. Recently Stewart-McDonald began offering "Restoration" tuners, which are replicas of the 1920's tuners but with somewhat better gear fit.

Waverly and Gotoh make a better grade of production tuning machines at a huge increase in cost. These tuners are as close to perfect functionally as is possible to achieve. In appearance, they are no better than the standard Grover, Schaller or Gotoh tuners. One difference is that the knobs are usually made from finer materials such as pearl, Ebony or abalone.

Most quality guitars  use either Waverly, Grover Rotomatics or Schaller tuners for steel strings and either Waverly or Sloane tuners on slotted head instruments with nylon strings.

Upper end tuning machines are made by master craftsman to order. The tuning machines made by Nicolo Alessi set a standard of excellence that has yet to be surpassed. His tuning machines are built around very precise worm gear sets and trimmed and finished in a variety of ways to suit the most discriminating and well-heeled customer.

Knobs for tuning machines are made from virtually any hard material. Custom knobs made from Ivory, Ebony, Abalone, Pearl, Bone and Horn are readily available. Other more exotic materials such as 10k Gold, Silver, Jade and other exotic woods are sometimes available on custom order.

Tailpiece 

The tailpiece is a functional component on archtop instruments that holds the lower end of the strings but is also a decorative piece. Tailpieces can be divided into 4 styles, formed sheet metal, machined metal, cast bronze and wood. The formed sheet metal tailpieces can be as simple as the standard Gibson that is literally punched from sheet steel to more elaborate ones machined from bar stock by skilled craftsmen such as Bill James. If one  desires the Gibson for that traditional look, be aware that it is far more fragile than the others and fraught with problems such as cover rattle and string attachment prong failure.

The most elegant and expensive tailpieces are cast from bronze in a variety of form factors. Those designed by John Montalone set the standard for any number of later designers including me. The most popular cast tailpieces are the Montalone made by Allen, the Custom Lefty and Orrico. Most cast tailpieces have elaborate artistic shapes as part of the basic design. Finishes include, natural bronze polished to a mirror finish, nickel, gold or colored lacquer. All are beautiful and highly functional. Most archtop guitars and all violina have the Sacconi style wood tail that has a cable looped around the end pin and is held in place only with string tension.

Tailpiece Decoration 

Tailpiece decorations include engraved names or logos in the top covers and in the case of my Custom Lefty a round pocket in the top is made to accept a disk of wood, metal or pearl. These disks can be engraved with any sort of name, logo, etched photo, etc. In the case of wood or metal disks, engraved pockets can be filled with gold or silver or an array of crystals.

End Pin 

The endpin is a functional component that is also decorative. The shoulder strap is attached via a slotted hole to this pin. A 0.350 opening is generally located in the center of the tailpiece-mounting flange. A tapered hole is drilled through this opening and a pin made from Ebony or other hardwood, plastic or ivory is press fit. Many wood endpins have a small pearl disk inlaid into the visible end as decoration. When an internal pickup is installed, a Fishman socket is substituted for the end pin that can serve the dual purpose of shoulder strap attachment and output jack.

Pick Guard 

The pick guard is both a functional and decorative part of many instruments. While optional, many desire a pick guard to minimize scratches to the lower surface of the soundboard. A good example of what can happen without a pick guard is Willie Nelson’s old Martin guitar that has a large hole in the top as the result of thousands of pick scratches. Most pick guards are made from either plastic such as celluloid or a hardwood such as Ebony or Rosewood. On mandolin family instruments the pick guard is usually attached to the fretboard support with two wire pins and to the rim with a single screw through a plastic, wood or bone brace. On the guitar, it is generally attached directly to the top with either double side tape or glue. I am not a big fan of pick guards on mandolins but believe that they are essential on archtop guitars.

Strings 

The selection of an appropriate string set is essential to achieving optimum sound from the instrument. On A and F5 type mandolins the string set is normally in the range of: 0.010 <E>0.0115, 0.014<A>0.016, 0.024<D>0.026, 0.034<G>0.041. For the bass emphasis sound style, the strings are always heavier, the size depending on too many factors to generalize. The string diameters are selected to achieve correct pitch at tensions of from 15 to 30 pounds. The E and A strings are made from solid wire while the D and G strings have fine diameter wire wound over a solid steel core.

On the longer scale instruments that have lower frequency tuning, slightly heavier strings are normally used. Strings are generally made from either stainless steel or phosphor bronze. For a sharp Bluegrass bark, the lighter strings are usually selected while for a balanced mellow sound heavier strings are normally selected. There are a huge number of string suppliers but for consistent quality, I have found none better than D’Addario or E&O Mari. More important than supplier, is selecting both the correct diameters and string material. Stainless steel strings generate a sharp ringing sound while phosphor bronze generates a deeper more mellow sound.

On Classical and Flamenco guitars I only use E&O Mari nylon/silver strings that are the gold standard all over the world.

Shoulder Strap 

It is very difficult to correctly hold or play an instrument without a shoulder strap. Straps are normally connected to an endpin protruding from the tailpiece and to either the scroll of the F5 or another pin/metal loop near the neck joint of the A-style and guitars. Though some prefer attaching the upper strap end to the peghead, this is not generally suggested. Shoulder straps can be as simple as a piece of string or leather thong or very elaborate things with decorations, the players name, etc. My preferred strap is the 4-ply round Lakota Leather made by Native Americans from either elk or bison skin.

Case 

When transporting the instrument, a sturdy case is essential. Cases range from the simple rigid plastic foam to elaborate graphite composite. The top end cases made by Colorado, Pegasus and Calton are air transport certified and will last a lifetime though they are quite expensive. A completely adequate case can be purchased from most music stores or on line for $100.

Display Stand 

It is not recommended to store an instrument in a closed case. Many of the plastics and adhesives used will slowly react with the instrument’s finish. The instrument should be stored either hanging by the strap on the wall/closet or proudly on a display stand. Simple display stands made from bent wire are available as are custom wood ones that are finished to match your custom instrument.