neck body joint on a classical

[Layne Campbell]

Hi,

I have built an electric posted last year, and now I am excited about building my first acoustic.

I have "guitarmaking tradition and technology" and I am planning on basically building the classical spanish guitar that he builds, but I am concerned about the neck/body joint. I live in a hot and humid environment, and I store materials in a dry box, but in general, anything I build is going to be more prone to warping then if I was building in the US. Because of this I am leery of his slotted neck block joint.

I would like to build the classical Spanish guitar, but with a mortise and tenon joint and an adjustable truss rod. would this be a problem acoustically for a smaller lighter nylon strung guitar? or is it simply not a traditional joint?

Thanks.

[Bob Gramann]

I have built a few classicals with butt joint, bolt-on necks and truss rods. They worked fine.

[Waddy Thomson]

Any type of neck joint will work on a classical. Many good builders use bolt on necks. No reason a mortice and tenon wouldn't work.

[Keith Ambridge]

I don't think you'll need a trussrod!

Keith.

[Alain Bieber]

Fleta guitars, which had the best rating among all classical guitars during almost thirty years were built with a tenon and mortice. Many Spanish guitars die progressively of vertical misalignment and the cure is not very easy when built with the standard method.
The truss rod can be avoided. It was considered good practice to build the neck with a slice of ebony or any other very stable hardwood stuck between the two halves. Those are made usually, even systematically since the sixties, in Spanish cedar, a light but very stable wood.

[Alan Carruth]

It's usually considered a good idea to keep the neck on a classical as light as you can, and, since it's already fatter than a steel string neck, that requires some thought. 'Spanish cedar' (Cedrella odorata, iirc), is often used, in part because it tends to be less dense than mahogany. It's also not as stiff, but since the neck is larger in section, and carries less tension, that's often not a problem in the short to medium term. As Alain says, eventually all guitars try to swallow themselves though their own soundhole, and some means of adjusting and eventually re-working them is a good idea.

Most truss rods are on the heavy side for a classical; the 'Martin style', with the aluminum channel , is especially bad, and 'way more than you need in any event. One of my students made rods for his own classical guitars out of titanium, and they worked great. I'd love to see the 'Blanchard' style double action rods with differential threading in titanium.

I've been using a tenoned neck joint on classicals for years. Recently my students and I have made a few using the tenoned joint in such a way that you can build on a solera. The idea is to make a separate block and join it to the neck using your normal tenon, but assemble the neck and block _before_ gluing the sides to the block. What I do is assemble them with a 2mm plastic spacer, which, when removed, leaves the slot for the sides. Then you just use the neck-block assembly as you would a normal 'Spanish' neck for the rest of the process. You do have to remember to cut out the top over the tenon, of course.

There are a few advantages to this. One is that you can make the surfaces that become the slot really smooth, and size them with hot hide glue before assembling the neck. This makes it easier to plug the neck in later. you've got all the advantages of easy alignment of the solera method, and the ability to unplug the neck later to re-set it if you want. It's an extra step as compared with the traditional method, of course, but not all that time consuming. Remember; you don't have to align the neck when you fit the tenon, and the block can be mae over size and trimmed down after things are assembled, so all you really have to worry about getting a good fit on the tenon itself when the spacers are in place.

[Layne Campbell]

Wow, Ok.

Thanks for all the really great and informative responses. I will go with a tenon joint instead of the traditional one. I just feel like it would be a shame to have the instrument become unplayable after a few years of warping, and have no way to correct it.

I will also probably do away with the truss rod. I got one of the Stumac Hotrods shipped over, but it is rather heavy, and I could just as easily put a thin ebony rib down the middle. or maybe I will give it a skunk stripe, I always liked the looks of those.

[Bob Gramann]

The only reason I use the truss rod in the classical is that it's so easy to dial in the relief to exactly what the player wants. I've been using the LMI double action rod (like the Blanchard but without the fine threads on one end) because I can get the length I want. I haven't noticed the weight.

[Matthew Lau]

Might I recommend Port Orford cedar?

I love the stuff as it's stiffer than Spanish Cedro and doesn't dent as easily.
It just doesn't look the same as Mahoganny (very light color).

[Trevor Gore]

Keep the truss rod!

You'll need it in an environment where you're moving in and out of air con and in and out of high temp, high humidity.

If you use cedro or mahogany with an ebony fretboard you'll discover a way of making a hygrometer and you'll need the truss rod to keep your guitar playable. Don't worry about "extra mass" in the neck. I use a truss rod in all my classicals and the majority of players wouldn't know.