William Cumpiano's 
String Instrument
Newsletter #24

MY SOUNDBOARD LOOKS LIKE A POTATO CHIP!

Can I expect a "warmer" sound?

I am curious what impact the different body woods has on the sound of the guitar. I have read that with mahogany one can expect a "warmer" sound. (less bright... less projection?)


I can give you the easy, pat response that luthiers usually give their customers when answering the common question, "what is the impact of different body woods?" --with the well-worn, and ultimately meaningless words "clear", "warm", "bright", or "dark" and attribute more or less of one or the other quality to the specific species selected for the back and sides. But I won't do that to you, mainly because it is misleading.

35 years making guitars has brought me to the conclusion that the guitar can physically respond to only a distinct subset or portion of the the total string's sound spectrum, creating it's own "version" of that spectrum. The guitar's effect, so to speak, on the string's sound--and thus, what we actually can hear-- is determined by among other things, it's size; it's string length; the way it is constructed; the massiveness or resilience of its neck; the thickness and hardness of the walls of its soundbox, the placement and cross sectional shape of its braces; the size and shape of its bridge, and on and on. There are so many factors impacting on the performance of the guitar--some which the luthier is aware of and can control by choice; some which are not controllable by the luthier because they are hard-wired into the guitar's culturally-determined form; and some which are beyond the perception and comprehension of the luthier. Each of these factors affects the sound, some dramatically, some slightly. The specie-name of the wood used on the back and sides plates fall into the "none at all" category. The actual sample of the given specie chosen rises to the just-perceptible category. Surprising?

In other words, I could say that Indian Rosewood results in a "brighter" sound than Mahogany, but there are extremely soft samples of Indian and extremely hard samples of Mahogany that would contradict this statement--the variations between samples of the same specie are dramatic. So it may be smug and easy to talk of the "warmth of mahogany" or the "punch of rosewood" but really, they are ultimately meaningless statements.

Besides, what sound am I eliciting in your mind when I say that Indian Rosewood results in a "clearer" sound than Mahogany? Does my statement that Mahogany results in a "warmer" sound than Indian really communicate accurately to you the sound difference that I perceive in my ear? Given all the myriad known and unknown factors in any given guitar that result in it's distinctive tone, am I safe to say that the "warmer" sound that I'm perceiving is a direct result of the wood specie? Or some other solitary factor or combination of factors?

So to conclude this overlong message, I find it not helpful at all to preoccupy myself or my clients about what the sound difference between two hypothetical guitars might be, one rosewood, one mahogany. That's because the perception of tone is a personal experience and not something that can be talked about, or written about. It must be experienced, it can't be described.

One difference is clear: it costs me about $20 dollars to purchase the mahogany used on a guitar, and $100 to purchase the Indian rosewood used on another; and $800 to purchase the Brazilian rosewood on yet another. And that difference will be reflected in the cost of the guitar, you can be sure of that! The fact is, the cost difference biases people's perception of the guitar's sound "quality" in many people's minds (or ears). One must be very careful of falling into that trap. The perception is that the Brazilian rosewood guitar is per se "better" than the Mahogany guitar, evidenced by the difference in cost, is incorrect. The Brazilian rosewood guitar is more costly because its materials are rarer, and to some eyes, more beautiful in appearance. But one is not "better" than the other--indeed, they may be simply different, or you may not be able to perceive the difference at all. And if they are different in sound, surely there would be no way to safely say that the difference is because the specie name of the back and sides is different.
 

Thicknessing criteria

Do you use a specific thickness for tops, backs, and
sides, or do your thicknesses depend on the wood
species used. I've been reading some conflicting
information on this topic and would love to hear your
thoughts.


I select all my soundboards for a certain familiar stiffness and springiness, and then reduce them to a specific thickness according to dimensions that have given me good results in the past. These given dimensions vary only regarding to the instrument size and the wood specie in question, not according the "tap tones" or "feel" of a particular piece as its being reduced--as some builders claim to do.

This is different from what I wrote in my book, which said that I tapped the top as I thinned it, and stopped at a certain ring. That was in 1985 when i wrote the book. Not 20 years later, because my approach has evolved since then.

As to the sides, they are strictly thicknessed in consideration with the bending requirements of the specie involved. And the back is thicknessed, again, according to species and soundbox size, the dimensions that have produced the best results in the past.


Case stains

My guitar has peculiar stains precisely the color of the case fabric and where it touches the guitar. What's happening?

I have seen case-related discolorations of the finish. In the past I've also seen the imprint on the finish when the guitar is placed in the case with the guitar strap still attached. In both instances, the case/strap material reacted with the case material. You may be able to polish off most of
the discoloration with some fine automobile rubbing compound applied judiciously. if it continues, wrap the guitar in a piece of bed-sheet material before placing it into the case.

It's the case material reacting with the instrument's lacquer finish. It's a process called "plasticizer migration" where solvents common to both materials come into mutual contact inside the case and "migrate" from one surface to another, leaving a mark or scar.


Good balance and response

I have been overwhelmed by the multitude of top bracing patterns out there. In your book, you imply, after discussing the various bracing patterns, that the idea of "stiffening the treble side" using any of the several methods (e.g., slanted lower cross strut or additional angled strut) may not "in and of themselves be that important" to improving the tone of an instrument. Is this still your observation? My goal is to strike a good balance between volume and good bass response.

Everybody's goal is to strike "a good balance between volume and bass response." And achieve clear, ringing trebles.

My conviction of the truth of that blanket statement--that the choosing of one bracing scheme over several is merely of modest or relative importance to achieving that goal--is even stronger now, twenty years after publishing the book. And so is the statements that follow on page 145, that conclude "The brace design in short, can only be as successful as the whole of which it is part. "

There is clear scientific proof that the soundboard's activity is only responsible for a limited part of the guitar's sound production--an important part--but just a part nonetheless. That's why the widely popular obsession over the soundboard is misplaced. When I hear people obsessing over brace size, location or placement, the way the ancient theologians debated how many angels fit on the head of a pin, I refuse to participate in the discussion.

The instrument's bass response is largely unrelated to the soundboard. There is no "bass side" of the soundboard, as if it were that side that produced the bass notes, just because the thicker strings are closer to it. The soundboard is too small to radiate any bass sounds. The low E fundamental has a wavelength of thirteen and a half feet. A twenty inch soundboard cannot radiate a thirteen foot wave. Or so I have learned from my research.

The bass response of the guitar is largely related to the volume of the soundbox relative to the stiffness or resilience of all its walls. Some of the higher frequencies of the guitar's spectrum are related to the stiffness of the neck, since the neck also radiates sound energy (remember the strings are attached to the neck too!). So the "good" balance between bass and treble response is a product of the "good" balance between ALL those factors. And a good balance only comes naturally to a builder who has over time evolved a design, that given his individual approach and the materials that are at his disposal, achieves this balance. And he's achieved that by...building many, many guitars--first, by slavishly duplicating the choices made on the guitars of the great masters (and not having to reinvent the guitar from scratch), and eventually over time, by achieving through repetition a sense of what is important and what is trivial.

So don't expect a magic phrase from me which will quickly and simply unlock the door to world-class consistency for you. All I can promise you is blood, sweat and toil--until one day you wake up and realize that all your guitars a striking "a good balance between volume and bass response."

 
Scalloped braces

Everyone seems to make such a big deal about them, but what are your thoughts on scalloped braces?

I don't know what justification is advanced by people who use them, maybe you should ask them how they can defend them--other than to say, "Martin used them on guitars made during the 20s and 30s, and since those guitars reputedly sounded so good, presumably it must have been the scalloped braces." Few people know that actually, those early guitars were originally braced for gut strings, and when decades later people swapped steel strings on them, their tops were all destroyed by the extra tension. But boy, they sure sounded great before they collapsed!!

The peculiar scallop shape, it seems apparent to me, must have originated as a result of an early voicing technique where (in the days when luthiers worked in factories, and not machine operators) builders reached inside with finger planes and removed material judiciously from the braces in stages as they restrung the guitars to progressively listen to the changes, and stopped when they felt the compliance was "right."

There's nothing magic about the scallop shape itself, just that it was the result of the well-aged process of using finger planes to remove material through the soundhole. But as it happens, that peculiar shape entered a realm of lore and mystery that subsequently drove aspiring luthiers crazy trying to decipher. I have been asked that same question by dozens of first builders.

Large, stiff, disappointing guitars are today "strutted" by some technicians who reach inside through the soundhole with finger planes to remove material from their "struts" to improve the sound. The result usually is to "hot rod" the guitar by making it sound somewhat louder and a bit deeper or bolder-voiced, while hastening it's demise. The guitar survives only if the braces were way too large to start with or if the the strutting is done with restraint.

The string's signal is nothing more than minute and rapid changes in tension (dynamic stress) amidst the constant background tuned string tension (a static stress). So the problem is to construct the top in a way that adequately supports the static stress without hindering the dynamic stress. It's the guitarmaker's dilemma: that the soundboard is really a trade off between structure and tone. If the brace heights are left high, the soundboard will resist the 200 lbs of steel-string tension with no problem at all, but with a price to pay insofar as the acoustical range that results: invariably a tight sound or a limited tonal response. Reducing the brace heights increases the compliance of the top to a wider range of signals coming from the strings and a more satisfactory acoustical response, but with a price to pay in its architecture. The builder is truly expert when he derives a sense of structure sufficient to dimension the top thickness and brace heights to achieve an optimum--say, minimally adequate structure.

So, the secret is not in the peculiar contour of the braces, it's in the acquired skill of the builder that senses the minimal structural requirements of the instrument and responds correctly when removing material. Note that Martin now again offers "scalloped braces"--as a marketing ploy, I can assure you, because no one in the factory is graduating braces. They are likely to be using thicker, stiffer tops to hedge their bets, and make it a point to insist that low tension strings be used.


Template curves

I have a question about creating the outline shape of a guitar. In your book you say that the template should have a flat portion of 1 1/2" on each side of the center line at the top and bottom. When I make some outlines the flat parts look awkward to me. I have noticed that many guitars, including the Martin 0000 size, seem to have a gentle curve going all the way to the vertex at the top and bottom.

My question is what difficulties would one encounter if the shape does not have these flat portions? It seems that the headblock and tailblock would have to be shaped to match the desired curve, and perhaps the shoulders of the neck tenon sanded to match the curve. I was wondering what other, if any, difficulties would be encountered in choosing a shape with a gentle curve rather than a flat portion at the top and bottom?


You'd have to curve the tailblock accurately, and curve the cauls that you use to glue the sides onto it, and curve the sides so the contour at that point matches the tailblock; and the headblock, all this applies PLUS you have to contour the curved bearing edge of the heel to match the curved surface of the sides. Then you have to do that while setting a precise neck-to-body angle at the heel-soundbox interface. If you want to work that hard, be my guest. It is far, far easier to set a neck to a flat surface than to a curved surface. If you haven't tried yet, you won't know how tricky that is.

Strictly speaking, the flat portion of the template at the headblock need be no wider than the fingerboard at that joint. The flat portion of the template at the headblock needn't appear flat at the guitar's back in the area of the heelcap. When binding in that area, you can soften the portion of the binding mortise that straightens out so that it doesn't appear to be flat behind the heelcap.


Finishing interiors and tuning braces

I preface this question by stating that I have been a piano rebuilder, refinisher, and tuner for 30 years.
What is your opinion about finishing the inside of the guitar body. On pianos, both sides of the soundboard are sealed with sanding sealer and lacquer thus keeping swelling from moisture to a minimum. I am inclined to do the same on the guitar body.

I have heard different opinions about this subject. Mostly the theory goes: It hasn't been done in the past so why do it now. Not a very convincing argument.
After 4 months of constructing a dreadnought (sandwiched between piano repair), I have glued the spruce top to the sides. The back is ready to be attached. I think that this is may be a good time to seal the inside of the body while carefully masking where the bottom will be glued to the sides.

Another point of interest to me as a piano tuner ( which I agree with you) is tuning the tone bars to a specific frequency. We modern piano tuners almost always tune to a "tempered scale." As you probably know, this means that, except for "A440" the notes are very lightly flattened so as to be able to play the piano in any key. When I restring a piano, I check its crown and also tap it while listening for the sound of a rich kettle drum (since no strings are attached at that moment.) If I were to tune the braces to a certain pitch, I would be producing an instrument which would sound good in only one key or pitch instead of any key. So when I read about tuning the tone bars with my peterson strobe tuner, I found it interesting but not a sound musical concept. One should listen for a resonate vibration from the soundboard instead of a certain pitch so as to be able to play beautifully in any key.

Long reply follows:

The reason why "mostly the theory goes if it hasn't been done in the past so why do it now" is because there is no DATA for finishing the interior of guitars. Nobody does it, nobody did it, and so there is no convincing data to persuade makers to add yet another procedure to their lengthy list--given that the great patriarchs of the craft never did it, and if you did it, there would be no way to clearly determine if it was indeed protective in some significant way--or to assuage the fear that it negatively affected the guitar in some way.

Stuart Mossman was the only serious builder who finished the interior of his guitars. But he's dead; his instruments were good, but not memorable or highly prized now. And the finished insides of his guitars looked peculiar, besides. In the absence of clear evidence or a track record established by someone else that to do this is somehow good, no established builder will do it. But maybe a newcomer such as yourself will to try it, utilizing the logic from another trade.

But I guarantee you. If your guitar comes out with a disappointing sound, you'll be nagged by the idea that maybe the extra finish "deadened" it. If it comes out sounding great, you may wonder how much better it might have been if you hadn't finished the interior. Or you may not. You might be able to present it as evidence that it doesn't hurt the sound much to do so. But you couldn't persuade folks that if it never cracks, it was the extra finish that guaranteed it--and not that it would have never cracked anyway. A lot of guitars never crack.

2- You're asking the wrong guy about "tuning" braces. I've advocated for years that all this "tuning" stuff for guitars was delusional nonsense, if not outright hogwash. I came to that conclusion after fathoming from my apprenticeship with a guitar acoustician that the guitar is an astronomically complex vibrational system, far more complex than any of the bowed instruments, certainly far more complex than all these folks talking about soundboard tuning appear to grasp.

When you see the tests, like I have, that show incontrovertibly that, for example, the headstock is the most acoustically active part of the guitar at some frequencies, and see over what an amazingly wide spectrum of frequencies the soundboard is simply silent, it drives you to conclude that all this preoccupation of tuning a certain brace or another to one note or another is just not worthwhile.

The guitar is a series of linked oscillators, or linked springs. Maddeningly they all feed back into each other recursively. The strings are springs. The saddle bone is springy. The bridge is springy, the soundboard is springy, the neck is springy, and when you pluck a string, it sets all the springs dancing. And then the springing guitar feeds energy back into the strings altering their behavior. So as tantalizing as the prospect may be, I don't believe tuning one brace to one note or another is going to offer me the keys to assured world-class consistency. It will simply generate more questions, more mysteries. And no conclusions.

Some of the problem springs, I suppose, from the fact that these cultural artifacts that motivate and compel us so, are called "instruments". It makes one think of an oscilloscope or a frequency generator, or some such perfectible precision scientific apparatus. The guitar is not some sort of energy-transforming machine that someone invented in the past and can be effectively tinkered with to "optimize" it. Optimize it to achieve...what? It is a cultural artifact, originally devised to satisfy the aesthetic preferences of a particular ethnic group at a particular time in history. It has been modified over the centuries to fit the evolving vagaries of culture, fashion and taste, not to somehow optimize it in some objective scientific/acoustic sense. There is no objective acoustic goal for tinkerers to reach. And if you find some kind an objective goal, you'll soon see that it is a moving target.

So I've shed all that baggage, and have come to see the guitar not in terms of an acoustical problem, rather an architectural problem and an ergonomic problem, It has turned out in my experience that when these factors are well resolved and reconciled--something which is very achievable--well, the result is a product that people will like and will pay for.


Truss rods

Do you still use your homemade truss rods? Already made are so inexpensive, any reason I should built one myself? (Quality, durability, etc.)

The book was written and published twenty years ago. There were no commercial rods that good then. The rods that are available now are cheap $9-20 apiece from Stewart MacDonald, Allied Traders and Luthier's Mercantile, and are double acting, which are better than the ones described in the book.


Workboard shims

Why do you use a paper/cork workboard shim instead of hollowing out the workboard? What are those two extra small cork bits on the shim above and below the soundhole?

The stiff paper is just a convenience--the cork tends to get beat up, and its easier to replace and to make new shims for guitars of the same size but slightly different contours.

The cork thickness should be no less than 1/8, since the soundboard arch is 1/8-inch. But the shim could be thicker. As long as the thickness is consistent and the workboard flat. In fact, 1/8-inch masonite would be even better than cork, because it doesn't "give" under pressure. But you need to bandsaw it while you can just cut a sheet of cork with a knife. If it's a workboard template that you will use a lot, I'd opt for cork and dispense with the paper altogether.

The small bits of cork that you add onto the paper shim (under the utfb and apex of the x) are sanded to the appropriate thickness so they span the space between the soundboard and the workboard at their location under the clamping shoe. You should take care when tightening down the shoe bolt that the soundboard does not distort. This can happen if the cork bits are too thin, if the entire soundboard shim's centerline and the soundboard centerlines are not aligned, or if the perimeter of the shim is too wide. The width of the cork perimeter on the workboard shim should be no wider than the side plus the kerfing. You need to fiddle with the shim and it's placement until the top doesn't distort when you snug down the shoe bolt. You can see this distortion best when the headblock is glued to the soundboard. If the shim isn't properly aligned or too large, or the smaller shims are inadequate, you will note the headblock tip back when you snug down the shoe bolt.


On bridge pins

I have been thinking about installing new bridge pins in my Cumpiano guitar. I am looking at some nice Brass or Walrus pins. What is your opinion concerning using Brass and (grooved or un-grooved) pins?

There is no strict standard for the size, shape and configuration of bridge pins. Indeed, there are almost as many different bridge pin configurations as they are bridge pin manufacturers. They are all within a general size range, but they have different tapers, different taper lengths. There are also at least three schools of thought about how the are supposed to fit. Some believe that the entire string should lie in a deep notch ahead of the hole and the pin needs to essentially just wedge itself into the hole which matches its taper precisely. That school requires pins with no groove; the other (most large mainstream manufacturers) have a "half-notch" in the hole and a groove in the pin; another school is the school of expedience (makes of cheapo mass-produced guitars) have no notches in the hole and just drill a straight hole big enough to wedge the pin and the string in it.

Frankly, I don't believe there is an acoustic advantage or disadvantage to any or either of these methods. The string is pulling so hard on the bridge, I don't believe that any better "contact" is going to make a difference: sound isn't like a "fluid" that will "leak" if there are minute gaps between the hole, the string and the pin. Anyone making a firm assertion one way or another has the responsibility of presenting some data to support his case, though--a highly unlikely event. So I take a more pragmatic approach.

If the pins I'm using has a groove, I'll make a half-notch. If not--and I anticipate their use when I'm making the bridge-- I'll machine a deep full-notch for the string. If I didn't anticipate their use and the bridge is on the guitar, and I must use a non-grooved pin, I have a little device that will allow me to mill a groove in the pins (which you can now purchase from Stewart MacDonald) and my problem is solved.


Preparing bindings strips for bending

A question came up when I went over my notes I wrote during our tutorial. I missed the trick you pulled on taping and gluing together binding and purfling. I was too busy doing something else, so I did not see exactly how you taped together the strips of wood. I saw the result and you told me this is what you did for the entire first week in the Gurian shop. But I cannot reproduce the neat trick you performed with the tape.

That taping process is easier to demonstrate than to describe. It's like trying to explain what an accordion is with your hands tied behind your back.

Essentially, you have to line up all the elements in the desired orientation flat on the table, then apply strips of tape perpendicularly across the top of the bundle every four inches or so. The tape strips must be somewhat over three times longer than the bundle is wide, and each strip rubbed or burnished down against the bundle while squeezing the elements tightly together. With the bundle of binding elements viewed horizontally, each of the tape strips must be oriented vertically and must begin precisely on (not overhang) the top edge of the bundle; cross the bundle vertically and be burnished with the fingernails so that they drop down the bottom edge of the bundle squarely and onto the table below--and the rest of its length smoothed flat gently so it just lightly adheres onto the table top surface. Don't burnish the remaining length of the tape strip onto the table vigorously.

Then place a long straightedge along the top edge of the taped bundle of elements, aligned and parallel to it. While squeezing the straightedge firmly against the taped bundle with both hands, draw them both down smartly over the portion of the tape strips (the tape "tails") taped to the table top. The bundle must mount the tails, not plow them down off the table surface. Pull the bundle down over the tails of the strips until they reappear again beyond the top edge of the bundle. That will allow you to pivot or rotate the entire bundle until it lays flat again over the tails, and once again pulling the straightedge down against the top edge of the rotated bundle, you proceed to alternately pull and rotate, pull and rotate, until the tape tails run out and have been looped tightly around the bundle several times.

You thus end up with a tight packet of binding strips (and purfling strips if you've added them too) that you can bend as a unit as if it were a unitary side slat.

More side bending tips

I am building my first guitar using your book and a kit from Luthiers Mercantile.Working with a universal bending machine and sapele mahogany, I would like know if I should bend the mahogany dry or place it in hot water before bending .Any advice you give me is greatly appreciated.

I find that Mahogany bends best when soaked for a short period, about 20 mins. (hot or cold water) and left to sit for another 15 minutes outside the water before putting it on the bender. But you'll still have to work out problems that may arise from the tightness of your bend, the texture of your pieces and the thickness of your slats. Thinner slats bend the easiest but tend become wavy in cross section if the pieces are wide, as for deep guitars. That's why the dreadnaught shape is the best for bending: the gentle curves allow for thicker slats to be bent, and the thicker slats bend without becoming wavy. But tight waists like on 000s or classic can pucker or wrinkle at the waist if too thick or bent (pushed down into the mold) too rapidly. Bring the shoe at the waist down particularly slowly, allowing for the heat and moisture to enhance the stretchability on one face and the compressibility on the opposite face. There are no guarantees in the wood bending business!


Screwing neck bolts into end grain

I was reading your site and planning on building a guitar using your book. I am glad to say I have read it through a few times and feel ready to go. I have looked at the hardware neck design and I like the simplicity of the design, while also appreciating its practicality. I was shopping for the parts and came across some insert nuts made to fit the same hex screws you showed in your hardware. I picked up the barrel nuts as well, but I was wondering if the insert nuts would work as well? They are basically large screws with the middle made for the hex bolt. It would only require two drilled holes for installation, and would be even simpler to assemble and disassemble. I have very little fine woodworking experience, so the only problems I can see are split grain in the heel block from a poorly drilled hole. Do you think this technique would hold up?

Every Taylor guitar is made that way, so presumably it's one way to go. My decision to go my own way is based on sound woodworking principle: never screw into end-grain; and the fact that the neck is usually tipped relative to the soundbox: my system provides a neat pivot and the Taylor system relies on the screw or screw-head bending when tightened--and, have you yet tried to introduce the threaded insert into it's hole in the tenon? You'll have a scary, difficult time: It's not only liable to split the tenon, and fiendishly difficult to get it started and seated just right. So take your pick.

 
On the Cuban "tres"

It´s Chris,the first Austrian tresero. We had some email contact 2 years ago while i was writing my thesis about the tres (unfortunately in German...). By the way, I told a friend about you (Richie from Graz/Austria) - he ordered a cuatro from you in the meantime. i have a "technical" question: I have an old Cuban tres - nice instrument with a very short scale (a real guajiro [Cuban hillbilly] instrument). in spite - or due to ? - the short scale it's hard to play. there's a lot of tension on the strings, which are attached to the body similar to a classical guitar (that means the strings are attached to the bridge - of course, I use strings with ball ends). Now some people said it would reduce tension if I would glue a baticola (tailpiece) to the end of the body and mount the ball ends there. i would then run the strings thru the bridge the same way as it is now. well, other people said, this would increase tension, and some say it wouldn't had any effect. so what is the truth ?

To respond to your question, if it is hard to play, it's not because of the short scale. In fact, the short scale should make it easier to play! You have to wind a longer string tighter to reach the same open note as that of a shorter string. It is likely that the strings are poorly adjusted at the nut and/or the saddle. That is more likely what makes it seem difficult to play.

The baticola was usually added after the bridge began to show signs of starting to pull away from the top. Instead of improving the glue seam and regluing the bridge--something that requires a lot of skill and some special tools--they would do the easiest thing: add the baticola. If the bridge isn't showing signs of peeling off, don't add a baticola. If it is, take it to a luthier to have it repaired. And ask him to adjust the strings more closely to the fretboard (something that may require additional fretwork, or neck work). Only if this is impossible, THEN add the baticola. The baticola will degrade the sound and projection of the instrument, usually. It's why so many treses sound so weak and wimpy. Then players are forced to pound hard on the strings to make it heard. Not a good thing, but common with rustic treses.

Guitarmaker's vises

I am not a guitar maker but learning to build fine furniture and am looking for an small Ulmia wooden vice and something came up from some time ago about a copy of it. I would be grateful if you could tell me where to buy on?

Ulmia makes a whole line of vises and clamps, but I presume you're referring to the Ulmia rotating-jaw "Universal" vise. Time was, you could get them in the US--but no longer. You have to go to Germany and pay almost $400+ to get an original Ulmia Universal vise. But Stewart MacDonald imports a copy which does the same job but has lower-grade castings and rattles around a bit because the parts don't fit as tightly. But they cost 1/3 of the Ulmia Universal price and they are easily available and are indispensable. So us poor guitarmakers have little other choice, but to get them.

Piano spruce

Do you think spruce from a piano soundboard might be suitable material for some thin fan bracing in a guitar? Or for anything else in a guitar?

Maybe just for thin fans, in a pinch. Ordinarily piano spruce is not sawn from split billets because it doesn't have to carry the string tension load. The cast iron frame does. But guitar braces do carry the load, so they should beoptimized for stiffness, i.e. sawn from split billets rather than sawn off randomly-sawn planks.


Fretting tips

What are your thoughts on fitting frets to the fingerboard before gluing it to the neck?

...a tantalizing prospect for people who hate whacking the last few frets over the soundboard of their guitar. It can be a valid technique with flat (classic) fingerboards. But with arched (steel-string) fretboards a number of difficult problems come into play. The clamping caul has to be shaped the same as the fretboard, and the centerlines of the fretboard and caul have to line up perfectly during clamping. The caul must at least transfer the clamping pressure along the tapered edges of the fretboard if not to the entire surface of the fretboard, to ensure a tight seam with the neck shaft. That's requires a pretty fancy clamping caul! Lack of precision in this regard can result in gluing an odd kink or random contour into the neck and fretboard, if the arch of the fingerboard and the arch of the caul haven't lined up precisely.

My guitars aren't moving. Help!

Over the past few years you've given me a lot of good advice. Shop owners are happy to take my guitars on consignment; but they're just sitting on them. My guitars are not selling, even though their quality is better than most anything on their racks. I know delivering pizzas is a better way to make extra cash, but building guitars is what I want to do. I was awake most of the night Monday, thinking about the next guitar I'll build...I can't stop myself. It seems to me the only people who would buy my guitars would be pros; most people seem satisfied with a flashy looking Korean guitar. I've built 10 guitars and sold 3. The last guitar I built is a monster; I can't believe it hasn't sold yet. So, if you have any advice on how to get the sales ball rolling, I would greatly appreciate it.

Your immediate situation is grim, but your prospects are bright. It's a matter of persistence and commitment. Period. No way to get around that.

Building a successful business takes time. And time costs money. That's why you can't start a business without capital--and not expect to dog-paddle for a long time. If your capital is going to your wife and Uncle Sam, you have to live from sale to sale, one way or another. The hard reality is that sales start up real slowly because few people will drop that kind
of money on an unknown quantity. Then, you become a known quantity. And you get more orders than you can handle.

I started my own business with no capital, but with no liabilities, either. I survived at first doing repairs, finding niches to fill (I made dulcimers for folkies when that was big), renecked bazoukis for Greek musicians in Astoria, Queens. It kept my shop open until I built a presence. I sold one guitar, then nothing, then another guitar, then nothing, then another, then another...like that.

Putting your guitars on consignment in stores is good, it's one way to at least get your guitars seen, if not sold. It's the presence that's important. So don't lose your confidence in your product. You start to build a reputation with your presence. Guitar shows, luthier conventions, are good for start up presence. Eyeballs count. People remember. The word gets around.

Then there are the stage-door Johnnies. More than a few prominent luthiers were struggling unknowns right until they got up the chutzpah to shove a guitar in front of a guitar celebrity in a back stage green room. Paul Reed Smith haunted and stalked Carlos Santana. Danny Ferrington haunted and stalked Brian Wilson. James Olsen stalked James Taylor. Their star soared overnight when their victims finally caved in. That may be your forte. But it wasn't mine. I had to dog-paddle for a long time because I preferred to wait for the world to beat a path to my door. If I were a different personality, history would have been different. You have to find a way that fits your personality.

How long can you hold your breath under water? Long enough? Then you deserve to succeed.

Should the X-brace be improved?


On your website Q&A section you said, regarding soundboard bracing; Would you agree that the "half-lap" joint on the x-brace is a weak spot, both structurally and sonically? I was thinking of making an X-brace of two pieces of curved wood rather like two letter C's back-to back, they would have a flat spot where they meet for gluing, and possibly pinning together with little hardwood dowels. I think this would give the x-brace strength and continuity, have you ever done anything like this?

I think you're asking the wrong person: I'm not an armchair guitar tinkerer. I'm not inclined to "improve" the guitar by imagining what may be flaws in it's traditional design and then imagine ways to remedy them. My approach is optimize the givens, not change them. But as Dick Gregory said, "I'm a vegetarian, but I'm not going to take the meat off your plate." So you're welcome by me to go ahead and try your scheme and see for yourself.

But you make two shaky assumptions: that the current x brace scheme needs more "strength" and that "continuity" is somehow a goal. Yet some vintage x-braced Martins I've seen dating back to the twenties have carried the string tension load for almost ninety years without any visible distortion. And have you considered it possible that one stiff x brace and one weak x brace is precisely what makes a steel sting guitar sound the way it does?

How deep the truss rod?

I am attempting to build my first guitar following the instructions in your book and have just completed the truss rod installation (except that I purchased a Martin-style truss rod instead of fabricating my own). I routed the truss rod slot 7/16" deep and the truss rod, which is square in cross-section, fit it snugly with just enough room overhead to install a spline that is slightly thinner than a popsicle stick. All seemed to go well but as I was admiring my handiwork, it occurred to me that the truss rod does not look like it is set low enough into the neck to fit underneath the guitar's soundboard when the neck is installed into the headblock. In other words, the thickness of the spline is less than the thickness of the soundboard. The Stew-Mac website shows a cross-section diagram of this truss rod installed flush with the top of the neck and directly against the bottom of the fretboard and the photos in your book (photo 4-64 on p. 91 for example) show the neck with the end of the truss rod protruding at about the same level mine does. Should I have set the truss rod a little deeper or am I overlooking something that will resolve this apparent problem? I would appreciate any enlightenment you can offer on this.

From listening to an engineer's lecture during a luthier's convention ages ago, It is my understanding that the deeper in the neck you install an adjustable truss rod, the more effective it is. But your lower limit is the bottom contour of the shaft; not so deep that only a paper's thickness of wood remains, but enough wood mass to remain rigid to the
fingers. The least mass I allow under the rod is 1/8-inch. So if your shaft is 5/8 and your rod is 3/8, the spline should be 1/8. However, the Martin rod is squarish, wider than mine, isn't it? So you have to allow more material under it (especially if your neck contour is a pronounced vee) so when you carve the shaft contour you don't expose the rod at its corners. Draft the problem out on paper to get a general idea of how deep you can bury it safely.
 

Steel string bridge finishes

I cannot find information on how to finish a steel string acoustic guitar bridge. I use water-base for the rest of the guitar and am now on my 12th instrument and am feeling silly because I do not know how to do this step. Recommendation please.

Unlike classic bridges, the tradition is to not lacquer over the bridge on a steel string guitar. Before gluing them to the top, steel string bridges are usually sanded to a very fine grit (ie., 500) and then taken to a stiff fabric buffing wheel, with a very small amount of black (if ebony) or brown (if rosewood) buffing rouge applied to the fabric surface. Then they are buffed against the wheel gently and carefully, until the wood's own resins glaze the surface. The rouge is usually a fine abrasive in a wax medium, so the wax probably remains to glaze the
surface too. And you can accidentally overbuff and distort the contour. Buffing also tends to reveal all the missed sanding scratches, so you usually have to go back once or twice re-sanding and buffing until it's perfect. Then you rub the surface with a soft clean cloth to even everything out. Don't get any rouge or goop on the underside gluing surface, in fact, to be sure, sand the bridge's gluing surface lightly with 220 grit and wipe the dust off before applying glue to it.


Intonation problems, again...

I just finished my fourth steel string guitar using your book as my
guide. The guitar came out pretty well except for one problem. When I
tune it to concert pitch, I'll play an E chord and it sounds great. Then
when I play D chord, the treble B & E strings play sharp. If I retune
those stings to correct pitch in the D chord, the B & E strings play
flat. I've rechecked my fret & bridge placements and all seem good. I
even filled in the saddle slot and recut it to be sure it was right on.
I've tried making new nuts and saddles to no avail. I'm up against a
wall. I don't have any other idea's. I was hoping you could put me in
the right direction????

All you can expect from a guitar that is well made is that the fretted
note at the 12th fret on each string is exactly the same pitch as the
12th fret harmonic. Period. This assumes the action is reasonably low,
the fret slots are cut strictly according to formula, the nut begins at
the precise zero point, the front edge of the bridge is strictly
parallel to the frets and the saddle centerpoint lies at a distance from
the nut at precisely twice the distance of the nut to the 12th fret plus
the .15 compensation (steel string) or .1 compensation (classic). Any
additional tuning problems that you can then perceive, assuming the
above is perfect, is unavoidably due to the compromises inherent in the
equal-temperament scheme of the fret interval formula, which is
immutable and you can't change.

If you've made the guitar as carefully as you say, I suspect you're
having a tuning problem, not an intonation problem. I don't know what
string-tuning method or sequence you are using which results in that the
B and E strings "play sharp" or "play flat" but if your method includes
tuning harmonics on open strings to fretted notes (or vice versa), your
tuning technique is flawed because it will only exacerbate and show off
the compromises that the equal temperament scheme of the fret intervals
needs to make in order to cram 12 keys into such a small space. The fact
that some fretted notes in a well-made and well tuned guitar (the six
strings tuned open precisely to a tuning standard) will nonetheless play
very slightly sharp or very slighty flat, that's because the harmonic
notes are members of a different scale (the natural scale, or scale of
nature) than the fretted notes (the equally-tempered scale). The only
technically valid method of tuning the guitar is to tune fretted octaves
and unisons on different or strings beatless.

I doubt that my explanation will erase all your concerns, because the
problem of tuning and temperament is far more complex than can be
explained in two paragraphs. Indeed, there are entire books written on
the subject (and problem) of Temperament, like fr'instance

http://www.amazon.com/Temperament-Solved-Musics-Greatest-Riddle/dp/0375403558/sr=8-3/qid=1164834198/ref=pd_bbs_3/002-5372000-8977651?ie=UTF8&s=books
http://www.amazon.com/Temperament-Became-Battleground-Western-Civilization/dp/0375703306/sr=8-1/qid=1164834198/ref=pd_bbs_sr_1/002-5372000-8977651?ie=UTF8&s=books

What I can assure you is that if you followed the instructions of the
book to the letter, your guitar will have the same quality of intonation
as any Martin or Ramirez guitar. If you feel that you have done so and
the guitar still plays peculiarly out of tune, I suggest you take it to
an experienced repair technician so he can diagnose the flaw in your
guitar's construction that you might have missed.

=================

I have some questions about you new neck joint system. I am currently
working on a dreadnaught project and am comtemplating using your system.
I do have your book as well by the way, and have been using it for
referrence on almost every step to make sure I dont make a mistake. I
have gone to my local Rockler store and purchased the connector bolts
and cross dowels that you suggest. However, the cross dowels they seem
to carry are a little different than the ones I see on your website and
in the example in that they have an offset hole and are less than 1/2
long. So, can you suggest where to find the cross dowels which are
longer and have a centered hole? I can see that the dowel is flush with
both tenon sides, so it must be 3/4 according to your book. So, what is
the minimum tenon and block depth you would suggest for the system? I am
working off of the McRostie Herringbone plan from Stew-Mac and the block
is 1 5/16 with a 3/4 wide x 3/4 deep tenon. I am thinking I will have to
beef up the block and tenon to accomodate the cross dowels. How will
that affect the guitar that I am building? It seems I will have to use a
shorter bolt, perhaps the 1 1/8 bolts should I use the current
dimensions of the block and tenon but it only leave about 1/4 inch or
less from the dowel to the tenon. Please let me know.

My tenons are 5/8" wide, which allows me to carve a slimmer heel.
Unfortunately the bolts that are ordinarily available are drilled and
tapped off-center. I have variously used a bolt longer than 5/8" and
hacksaw the protruding end, or a shorter bolt that ends up flush on one
end and falls slightly short of flush on the other; in either case, both
work just fine. So don't be afraid if the bolt ends shy of flush on one
face of the tenon. The system works perfectly well.

==================

A mandolin is not a guitar

If I may, I'd like to ask you a few quick questions about mandolins.
First, is it possible to commission a custom-made mandolin with you? I
don't recall seeing anything on your website specifically related to
mandolins; however, if I'm going to have a once-in-a-lifetime custom
fretted instrument of any type made by anyone, your name is the first
that comes to mind.

The second question springs from simple curiosity. I am wondering why
most mandolin bridges are not permanently fixed in position. Each time I
restring my mandolin, I am at pains to maintain the same precise bridge
placement or, if I goof and put the thing out of position, to replace it
exactly where it was before in order to achieve correct intonation.
Major PITA. Since I'm only attempting to put it in the exact same place
every time, why not fix the sucker? One possible explanation that comes
to mind is that ebony will tend to wear faster than the
bone/ivory/tusq/etc. saddles used on guitars, so it's therefore
necessary to fiddle with or replace mandolin bridges comparatively
often, making it impractical to glue them to tops. But if that's the
case (I have no clue), why not use a bridge/saddle combo more akin to
that used on guitars?

Thank you for the request, Zuri, but I am not accepting mandolin
commissions at this time.

On some mandolin types, the bridges are fixed, like you seem to prefer.
Having said that, it's actually a benefit to have a bridge that is not
fixed, because one can set the correct intonation as needed for
different string height settings and string gauges. And most
mandolinists that I know replace the strings one string at a time so as
not to disturb the current bridge position--as do violinists. As to why
it's not done the way it's done on guitars, the simple answer is,
instrument designs, as they have been handed down to us from history do
not always follow a rational process. A mandolin is not a guitar. And
that is reason enough. Both evolved over the centuries in different
ways, to fulfill the musical needs and pleasures of different players,
cultures, and musics.

====================

Bending cocobolo

Hello Master Cumpiano, greetings from Romania.

First,I will tell you, for me classical guitar is a pleasure.
I have a friend who already build 80 classical guitars.He tried now with
cocobolo. But we have some problems with cocobolo.At the bending process
of sides; a crack apears at one sides.
I read at the others guitars makers web pages that cocobolo have a lot
of oils and resins, and water can't soft the sides before bending process.
If you can advise us about working with cocobolo will be very glad.
My friend bend the sides with a bendings irons with butane gas.
I use to bend a bend machine make by me with 3 electricals bulbs. I
don't try yet to work with cocobolo.But the cocobolo will arrive to me
probably next month.

Another questions is the fresh cocobolo bend easily? (he retain a lot of
water at begin, with time pass the water goes out and the wood became
harder and stiffer, and I think he became more difficult to bend)

I have allready read about gluing with titebond work real good.The
ultimate titebond is better for gluing?(Titebond Glue III Ultimate 16 oz )
I use this titebond Titebond Glue Original 16 oz

If i wet the sides in warm water is useful or not?

A higher temperature from bending machine is useful to bendinng easily
or not?

It is true after the drying process is almost complete the cocobolo
doesn't absorb water?

And, greetings from Western Massachusetts, USA!

I use cocobolo frequently and yes, it is more difficult to bend due to
it's oil, and it's stiffness. And occasionally it does break. That is
always a danger, no one can protect you 100% from that. But the way to
reduce the danger is to be consistent:

1- the temperature of the surface of your mold must be 300-325 degrees
Fahrenheit (149-163 C). I don't know what temperature your light bulbs
are producing. But the surface has to be 300-325 degrees F. At that
temperature, the oils will come out on the surface and darken, but they
can be scraped off afterwards.

2- the sides must be reduced to a consistent thickness of .080 inches.
That's 2.03 mm. You need a measuring caliper instrument and an abrasive
planer. And 2.03 mm is the best thickness: 2.28, or .090 inches, is too
thick, it will easily break. The problem is what is the thinnest you can
reduce the sides, while retaining their integrity. .080 is the size.

3- I would stay away from "fresh" wood, in any case. Bending fresh wood
makes sense only for furniture. But when we're dealing with such thin
sheets of wood, it might be easier to bend-- but when it ages, it will
be all rippled and twisted. But use only well-seasoned cocobolo that is
not crazy-grained, but instead straight and uniform in figure and texture.

4- Apply pressure to the wood in the mould very slowly, let the wood
heat up as the pressure is applied. Leave it in the mold for 30-60
seconds before shutting off the power or turning off the gas. Don't
leave it in the mold with the heat on for much longer, the wood may
begin to darken. The oils on the surface will darken but that can be
scraped off Let it stay tight in the mold with the heat off overnight
before removing it. It will keep its shape longer. If it changes shape a
little bit while it waits to be assembled, I use a hot pipe to touch it
up back to the template before assembling it.

5- The difference between Titebond Original and Titebond III Ultimate is
not important for guitarmakers. Titebond original is excellent and good
enough. Titebond III has advantages that don't concern guitarmakers: its
waterproof, you can glue it safely when the room is as cold as 11
degrees C, you can keep the joint open longer before closing it with the
glue applied. All those are unnecesary for us. You can go with the
Original. Unless you want to use the guitar under water!

=================

Which system for routing the binding ledges is best?

I am a builder of ukuleles and shall be adding tenor guitars to the list
shortly. I utilize radiused tops and backs and I am looking to build a
edge routing jig for use with a laminate trimmer. There appears to two
main schools of thought concerning these. (1)The stationary router jig
base and the mobile instrument and holder, or (2)the stationary router
jig base and stationary instrument and base, but the router is on a
movible armiture to reach over, up/down, and around the edge. The later
would appear to be a bit more desirable. Please tell me what you prefer
for eedge binding in instruments with radiused tops and backs.

I've tried the different schemes and devices and they all have certain
advantages and certain drawbacks. It really depends on which advantages
you prefer; and which drawbacks you can't live with.

After trying several devices where the router is suspended over the
instrument with a movable or counterweighted arm, and some expensive
router base attachments, I've emerged still preferring my original
choice of a hand-held router with a laminate trimmer wheel attachment.
It results in uneven-depth binding slots, which I then have to carefully
and laboriously deepen; but the setting and adjusting of the router is
simple, foolproof, and disaster-free.

The other alternatives promised to produce more accurate, even-depth
even-depth binding slots-- but only after difficult setting up and
adjustment of the guitar box and router--and then it was easy to
accidentally cut too deep. So until someone comes up with a
simple-to-set-up, goof-proof, suspended router device, I intend to
continue with my hand-held router with laminate trimmer attachment.

But I can see others who devote the time to perfect their
suspended-router technique can eventually master it to advantage. But
I'm content with my own mastery of a hand-held router, even though it
may take a little longer.
==========
Pinless steel string bridges

I am working on designs for a new guitar and would like to try a pinless
bridge. I like the simplicity of string changes and the clean look. In
your experience does this type of bridge have a marked affect on the
tone of the guitar, and also is a bridge plate still necessary?

I'd definitely shy away from putting a pinless bridge on a steel string
guitar.

Pins anchor the strings to the bridge and soundboard and not to just to
the bridge. Ball ends pulling up against the bridge patch and pins
hooking into holes in the top result in a more secure mechanical
connection between strings and soundboard. Having the strings end at the
bridge dumps the entire load 100% onto just the bridge's small glue
seam. I've just seen too many Ovation Balladeer bridges peel off their
soundboards to try messing with an old, well-working tradition.

Indeed, if I were required to use a pinless bridge, I would doubtlessly
use a bridge patch. Few people realize that the bridge patch also
functions to stiffen the soundboard under the bridge so it's harder for
the soundboard to just peel off the bridge under stress. The bridge
patch protects the integrity of the bridge's glue seam besides providing
a hard bearing surface for the ball ends.

But it won't stop the glue seam from failing because too much load is
being directly dumped onto too small a gluing area. The bridge would
probably not just peel off, it very well may pop off. But if you must
use a pinless bridge, increase the size of the glueing area by
increasing the size of the bridge over that of the standard pinned
bridge AND make sure to include a sizeable bridge patch.

=======================

Can't find a router edge-guide attachment for routing binding ledges.

I am in the process of making ( struggling with???) my first classical
guitar using the methods outlined in your book. It is unquestionably the
standard in guitar construction with a level of detail that others gloss
over. I have found the purflings and bindings to be the most challenging
to date. I am using a Porter Cable router and would deeply appreciate if
you could please identify the adjustable edge guide that you use to rout
the channel on page 247 as I have had great difficulty in locating one.


I bought my first Porter Cable router in 1969, with the "laminate
trimmer guide" pictured in my book. Porter Cable has long since stopped
selling the trimmer guide and opted instead to offer an entirely new
line of laminate trimming routers. Sadly the guides for that new
category of routers is inadequate for binding guitar ledges. So you are
stuck with a Porter Cable that you really cant use for binding ledges.
You may try to find th original PC laminate trimming guides at flea
markets or used-tool websites, or if you're a tinkerer, fashion a gadget
with a bearing wheel that you can jury rig to your router's existing base.

On the other hand, these smaller, specialized laminate-trimming routers
have become popular, and a host of other manufacturers are offering
them, some with rolling edge guide attachments that look just like the
old ones on the Porter Cable. A 10 minute search on Google reveals what
appears to be a suitable replacement willia3715Aaron J"Detailat:

http://www.amazon.com/DEWALT-DW670-Fixed-Laminate-Router/dp/B00002232G/sr=1-10/qid=1172075745/ref=sr_1_10/002-5234291-1922424?ie=UTF8&s=hi

I'm sure there are other different models each with their own similar
bearing guide.