Acoustic Guitar Construction

I too started out with the David Russell Young book. But unlike most (all?) who posted so far, the "butt joint" didn't scare me, nor did the steel reinforced neck.

Tone wise, all that weight in the neck adds to the sustain. I believe this is because the weight prevents much string energy from moving the neck, thus forcing it to exit by the top. I've noticed lately one supply house advocated Indian Rosewood for necks because it somehow adds "ring". Could that be simply a function of weight and its effect? I think so.

There is, for sure, comfort in knowing that if humidity and/or temperature changes cause the neck to move, you have a way to put it back. But consider this, steel, while also affected by these factors, is affected very very little compared to wood, and is many magnitudes stronger than wood. So, in my experience with the guitars I made in the 70s, the steel won the contest. Like DRY suggested, a neck correctly carved, retains its geometry when reinforced with a 1/4 x 1/2 inch bar of solid steel laminated into a well fit slot with aircraft expoxy - AMR 101, of which I still have some and the last time I ordered, it was available. It features the added piece of mind that if, by chance, jet fuel splashes on your guitar, the epoxy won't be affected.

More scary is the butt joint. Everyone has seen so many failed dovetails that it is difficult to imagine how a butt joint could not be worse, much worse, as there is no mechanical "trapping" aspect. So, the little chicken in me caused me to improvise his joint slightly. I added a strap at the bottom. That is, the last lamination at the bottom of the heel extends, one way or another, into the end block. Some guitars, like "Rip" (see my website at linkguitars.com), where it takes the form of a teardrop that uses the point on the heel as its point, but the bulbous body crosses into the body via a recess cut through the back and into the end block. Other times I extended the last lamination under the back, but through the block, forming a foot like the Spanish approach to the classical guitar, and glued the foot not only through the end block, but also the inside of the back after it leaves the block. I built a 12-string like this in 1976, 14 frets, and it has been strung full tension ever since. In 2005 I measured the neck relief at 7th fret as .003" treble and .006" bass. (Always contour the fingerboard to give me more room for the bass strings.) Action at the 1st fret is .007" treble, .016" bass. Action at the 12th fret is .042" treble, .052" bass. This is using D'Angelico light steel strings. The bridge is fully compensated for all 12 of them. This is a much closer action than DRY recommends but it never buzzed and many have played the instrument quite hard.

Thus the fingerboard serves as the top strap and the heel cap or last lamination of the heel serves as a strap on the bottom. In the end, it is a very solid joint that is easy to fit precisely, as you can see by the close tolerances in the action.

One advantage of the DRY approach is that it encourages one to measure 15 times, make adjustments as needed, think about it, dry fit it 15 more times, then glue it once, because once is about all you can get. However, I found that by clamping the neck in a simple jig and heating it with a model airplane "monokote gun" I could alter the final geometry very slightly if I wanted.

The problem with DRY's design is that it, like many, does not allow for voicing the guitar. The top tends to be too thick, given how short and wide the braces are. While no apriori system can be absolutely characterized without considering the actual wood used, his specs tend to produce seriously over-braced guitars. However, for these same reasons, they tend to have a lot of sustain, yet also retain clarity and can be played hard without over-driving them into harshness.

He also neglects to add a strap over the top of the lap joints in the bracing, 1 in the case of a 6-string, and 3 in the case of the 12-string, which is partly ladder braced. I added them because the physics of leaving them off is not just to cut the strength of one brace in half, but actually it is more like weakened 87% because strength is a function of the cube of height.

What I liked most about his book was that he did not descend into "magic" and "hunches" and "his experience". It was all logical based on common sense, and well defended, even if I did not entirely agree. His English is very clear too. He makes his points, one after the other, and gets out of the way. There is one miscalculation in the fret distances, but anyone with a calculator, or good source, can detect and fix it. Other than that outright mistake, you can make a pretty darn good guitar just following what he says. He is especially wise to tell us to lay off the decoration unless we really know how to do it.

I discussed the Somogyi books on Amazon, so won't repeat that here. But when you add them to the DRY book, it is a very good place to begin the serious study of what it takes to make a great guitar. The Somogyi books are less expensive if you use the amount of information delivered per dollar as your metric, but DRY gives you many specifics, most of which can be used as starting points for your consideration of what Ervin Somogyi has to say. There are specifics in Somogyi too, but there is so much in those books that I am on my 10th reading of them and still finding new stuff all the time - I understand how they can overwhelm. DRY takes you from the beginning to the end of making a fine instrument that is good enough that most of its differences with other instruments must be considered as just that, differences, not superiorities or inferiorities.

Above all, I have not found any problems with the steel bar or butt joint (as I modified it) after 35 years at full tension on any instrument I built that way.

I think many of us underestimate the strength of a well-glued joint, butt-joint included. Key words there are well-glued, as in following all the recommendations of that particular glue manufacturer. One of the projects I have sort of just begun (just rec'd the plans and will be crafting templates as guitar parts are drying) is to build a mahogany runabout boat named "Daydream Believer" (wife loves the idea, isn't aware of the fact I have begun it). Interestingly enough, most of the joints between the ribs, keel, chines & sheers (the outside edges of the boat that curve around the frame) are assembled with nothing but glue (West Systems System III epoxy, in MANY cases, actually), and the boats last for YEARS without any problem. Sloppy joints or dry joints will definitely cause problems, but if dry fit and glued properly, I have come to learn that a guitar neck is well within the strength capabilities of epoxy or the glues we typically use. This type of joint in a guitar certainly has its drawbacks, but strength, when executed properly, is not one of them.

There are NUMEROUS home-built airplanes where the wing ribs and spars are assembled with nothing but glue. If my boat sinks, I can swim. I can't fly, but thousands of planes are flying under this type of construction.

Recent post from the boat building forum you might find interesting:

"Epoxy is unbelievably strong.
Here's an interesting true story for you,

When they were designing the F16 fighter they wanted a way to fix the wings to the fuselage that left a perfect smooth seam but yet did not want additional time and cost added to the production. They decided on using an advanced epoxy. the aircraft passed all flight tests and exceeded any G-force that had been applied to any aircraft before and the airforce were delighted. Later when the airforce guys asked the engineers how they managed it they were told epoxy.
Allegedly the airforce guys were terrified at the idea of a wing being glued onto a plane for fear it would snap off mid flight, so as a compromise each wing was also fixed with an unnecessary but large rivet at the wing root. That rivet is now called the chicken rivet.

If epoxy can handle those sorts of stresses you can be assured that it will be more than sufficient for a boat joint as long as you make sure your mix is correct and it is applied properly."

Interesting observations Ken. AMR 101 is aircraft epoxy. Two of its most useful characteristics are tolerance of less than perfectly tight joints and its affinity for gluing metal. This last property is why DRY used it for gluing in his steel reinforcing bar. If the joint is halfway decent (I always square the ends by routing the slot short, then finishing with chisels), you get a complete lamination, rather than a piece of steel floating in a tight chamber, which is how most truss rods work.

My last supply of AMR 101 came from ARM Industries in 2003. I realize we are not supposed to hawk lutherie supply houses here, but AMR Industries is not that and sold to me as a courtesy. It is hard to locate. You can look them up on the web for a phone number, which is the same one printed on my cans of glue. Their web site appears to be down and I am not sure they are still in business. In 2003 a quart cost $175.00. I tested it a couple of months ago and it appeared to work fine, but I am a little uneasy about using it because of the age. When the Duke of Pearl sold it out of Erika Banjos he sold it in smaller quantities. His new outfit does not sell glue.

Perhaps Ken could steer us toward other advanced epoxies that would work just as well. There is no need for protection against jet fuel, but good adhesion to metal interests me. Many epoxies bind poorly to metal.

The structural weakness in the DRY butt joint is the fact the neck side is typically end grain, though you can arrange the laminations to present a better side for gluing, but then you have end grain showing against the main part of the neck under the fingerboard.

As an aside, properly laminated necks are structurally much stronger than one-piece necks, another virtue of the DRY book, which advocated them at a time when one-piece necks were generally considered superior due to the fact Martin used them. If the runout on a one-piece is perfect under the fingerboard, it becomes treacherous after it reaches the headstock, so that is where they break, sometimes with just minor provocation.

I've often wondered what David Russell Young guitars would be like today had he continued making them. One from the Eric Clapton collection sold for a little over $30,000 at auction about a year ago, butt joint and all. I speculate that his preference for logic over myth would have led him to a lighter, more responsive instrument. But in a market where you can get a good instrument from Martin, Guild, or Gibson for relatively small money, the hand maker faces an uphill battle. Restoration and repair is much more lucrative, though not as interesting and creative. He was probably right to switch to a field where factories were not the dominant players.

My $.02 ---- Solid truss rod --- glued neck butt joint -- just because you can -- does not mean you should. Martin finally came to the realization that wood, in time (and especially with change in environment) will move and change shape. Bob Taylor built an empire knowing guitar necks will at some point need an adjustment. There's plenty of $100,000 guitars with neither of the above features, some are art works some are great guitars. But I really like the book and I am grateful that it was published.

Kencierp: The neck joint question is a big one in lutherie now that there are options. As far as tone goes, the main consideration to me is that they are solid, to prevent any string energy from being used up moving them. Once that standard is met, your statement "just because you can - does not mean you should" applies to them all. In the end, one must choose something, right? And clearly it must be possible, something you "can" do, right?

You are certainly on target about Taylor. I would add that his special contribution is ease of adjustment and the quick return of solidity and playability at minimal effort and cost. Taylor's method requires a large investment in machinery, though. John Mayes has devised a simpler approach that can be executed with "normal" shop tools and accurate jigs. Owners of those guitars can rest easy with the assurance they will never need an expensive reset, though they may well need a reset eventually. Seems like anything that is built to be adjustable eventually must be adjusted. Some notable luthiers, John Greven, for instance, object to the weight metal bolts and nuts add; others, like Ervin Somogyi, want to eliminate any possibility of motion in the joint to ensure no string energy is ever lost. Given that Somogyi's tenons are vertically doweled into the block on both sides and strapped across the top with carbon fiber rods, I doubt they will ever move. The portion of his neck that is free to move is equipped with a two way truss rod like most others. I doubt owners of his system will ever need a neck set, minor or major. He says the total solidity of his joint gives his instruments an extra edge in sound.

There are other options too. Michael Gurian had one when he was building, Cumpiano has offered a couple, and there is always the ubiquitous dovetail. To my mind, the dovetail, while it can work well if perfectly cut, remains the most problematic, mainly because they are not always perfectly cut.

Many Martins "feature" a sizable gap on the back side of their dovetails that ensures they will need adjustment, but glue everything together in such a way as to ensure that making the adjustment will be difficult. (Those dovetails would not pass muster with most amateur woodworkers, by the way.) Newer models may have tighter joints - I have not seen any to say one way or the other. Teeter's book shows one of these gaps large enough for him to fill with water and insert a table knife as a heat transfer device to loosen the glue holding the joint so he can perform a reset. That alarmed me. But I know the bolt on solutions usually leave a gap too, to ensure that plenty of pressure can be applied to the face of the block.

Martin also used a solid truss rod for a period, though it was configured as a "T" which meant the part that protected against upbow was minimal, compared to the 1/4 inch wide steel DRY devoted to this function. Nor were Martin's T-bars glued in with epoxy designed to adhere to metal. Now of course, they use an adjustable truss rod like most everyone else.

What I like about DRY's approach to the neck and its attachment is that he analysed the issues and addressed every one of them with plausible, well explained solutions, solutions that for me (slightly modified) have held up for 35 years. He did not hinge it all on arguments like "dovetails (substitute your fave system if you like) give the best tone", as Martin sometimes does. Instead he was one of the first to challenge the dovetail tradition on realistic grounds, which has lead to a number of attractive alternatives, some of which are easily within the reach of hand makers.

And, of course, some interesting conversations. Which, in turn, are likely to lead to additional alternatives.

You have not addressed the overbuilding issue that I think following the DRY method in his book leads to. Was it modified in the second edition, which I have not seen? The guitars I built definitely have both the pluses and minuses of overbuilding. How about yours?

Link -- Do you have a real name? We like real names

Anyway, I am not trying to address anything -- I simply recommend this book. And that in my view David's neck joint and truss rod set up are things I don't recommend. And after almost fifty years in the business nothing will change those opinions. I can say that each of the eight David Russell "shaped" guitars I've constructed fall farther and father away from the design layout in the book each became lighter and lighter in structure, much less top and back contouring, slimmer necks thinner materials -- more modern. And while not quantum improvements each played better and sounded better then the last.

The forum is to express views -- so by all means continue to do so. But on these points I am not a good target audience or for that matter an audience at all.

At Stew Mac I was not allowed to use my real name when I did a recent review - for a reason that was not clear to me because most do - so I used my guitar business name which their computer accepted . For the sake of consistency, I used the same "Stew Mac" name here. My real name is John Link. I'll be happy to change it to that if your computer permits.

I was trying to elicit information, not change your mind. But I did want those who never tried DRY's neck joint and neck reinforcement - including you - to know it works. Now that you have this information, you can say you have heard it can work, but don't use it because of x, y, or z.

I'm also looking for suggestions for epoxy that is rated to hold well on both wood and metal besides AMR 101..

Finally, I love a good conversation and have not been disappointed at all on that score. You may not be a "good target audience" but you were one of only two who responded. I appreciate that, especially knowing that you lightened up on DRY's construction specs.

Myself, my biggest criticism of the butt joint is that it makes the instrument hard to sell. Most people won't accept it, like once most people would not accept bolt on necks once upon a time (and there is still resistance to them). I once visited the shop of a very excellent luthier when he lived in Kalamazoo. He had absolutely nothing to be embarrassed about regarding his superbly crafted and powerful sounding guitars, and I felt privileged that he handed me an inspection mirror to look inside. But as he did, he apologized for the bolt on neck that he knew I was about to discover. He was a young guy and offered a lifetime guarantee and I surmised he didn't want to spend a lot of time doing free neck resets on down the line. Bolt ons don't necessarily obviate them but they sure make a quick job out of it if the need arises.