Wednesday, September 22, 2010

My class and the joy of the 25 foot spherical radius

Gluing the top
As it turns out, I'm very lucky. Not only is my class very small, with only two other students, but both have already taken the class and finished their first guitars. That means that our class will be a little more advanced than the last and that I'll be challenged to learn a little more quickly. That's good, right? Uh....I think so.

Actually, I'm sure it's true. My classmates, Ron and Bruce have made me feel welcome in their class and have done their very best to not laugh when I ask stupid questions. I admire them already.

So far, we've made a few important decisions and have already completed some very important steps in the building process. First, we had to decide what type of guitar we wanted to build, and what type of wood we wanted to use. I had already made the decision that I wanted to build a very traditional, standard flat top guitar, so I chose to build a Dreadnought made with spruce top (red spruce in this case) and East Indian rosewood for the back and sides of the instrument. Guitar players would know this combination as very standard - like a Martin D-28, for example. That's considered by many to be arguably the standard in steel string acoustic guitars over the past 75 years or so. You'll find many bluegrass, country, and even rock and roll guitar players playing a Martin D-28 made from spruce and rosewood.

So the first three classes have involved learning a few important concepts and actually beginning the process of construction. For me, I learned something completely new in the first class. In all the years I've been admiring flat top guitars, I never knew that a flat top is not, in fact, flat - at least not in many cases, the Martin D-28 among them. Instead, the guitar is constructed with the shape of a 25 foot spherical radius. (Man, I love that). What that means is that the top and the back of the instrument are actually arched so that if the plane of the top or back continued, it would create a sphere 25 feet in radius. (Think about that for a second and you'll be able to picture it). So building the internal structure requires not only the skills of a craftsman, but a mathematician, too.

And since the top and back are both constructed of two pieces, they need to be glued together. It sounds like a pretty simple process, but planing the edges so that they join together perfectly takes a sharp plane, a smooth stroke, and lots of patience. But with a little time and many adjustments, I managed to get it done, and both pieces are glued and ready for the next step.

The other step we completed was the building of the internal braces for the top and back. This is an enormously important step, since the bracing is one of the most important factors in building a guitar that will be strong on one hand, while still being light enough to allow the guitar to vibrate freely. And THAT is what makes a great guitar. So I won't bore you with the details of our discussions about the bracing, but suffice it to say we spent quite a bit of time discussing the options and finally settling on a system of bracing that's a bit more modern than a traditional Martin would use, but still based on that basic system.

So the idea is to create two pieces of wood for both the top and bottom that create an "x". (By the way, it's somewhat unusual to use an "x" bracing system for the back, but we decided there were enough advantages to use it). [Editor's Note: In the end, and after much discussion, we decided not to use "x" braces for the back, but the standard "ladder" braces instead. "X" bracing will be used for the top]. Each of the pieces of wood used to construct the "x" braces need to be strong, yet light, so we spent a lot of time shaving the pieces down to eliminate any unnecessary bulk. Each piece is a fairly narrow strip of spruce, so they're strong and light and easy to work with. After cutting them to size, we used a jig on the sander to sand them to the proper radius to allow for what will eventually be a guitar with a 25 foot spherical radius.

Who'd a guessed?

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