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IntroductionAs part of a project class at the Caltech music lab, I studied the sound properties of an acoustic guitar through the various stages of its construction. The project involved building a steel-string acoustic and measuring the sound properties of its many components at various steps throughout its construction. By measuring the frequencies produced by the pieces when tapped, I gathered data on how the sound properties of the wood changed over time as it was sanded, glued, and assembled into its complete form as a working instrument. The soundboard, for example, I measured 1) as a piece of raw wood, 2) after being sanded to its final thickness and cut to the outline of a guitar, 3) after installing the bracing to make it stronger, and 4) after attaching it to the body of the guitar. By studying these changes as the guitar develops, I hoped to better understand the acoustics of the instrument itself -- why it's the shape that it is, how the necessary constructional constraints affect the sound, and what the general form of its frequency response is.
The guitar has been finished and is now a fully functional instrument. And I’m pleased to report that the sound is wonderful -- very full, rich tones (the rosewood loves those bass notes!) with surprisingly good projection. I couldn’t be happier with it! Now if only my playing did it justice...
Thinking about building a guitar?In case you're interested in building your own guitar, here's a little more about my experience on this project and some first-hand advice that may be helpful:
Before you start:Since I have never undertaken a construction project as complex as this, my learning curve for the woodworking has been quite steep... I would not have gotten very far without the help of some good references (websites and a guitar-making book) and the assistance of a very good friend who's done this before. The first two months were all information gathering. The more sources you have, the better off you'll be. Sure, a lot of them will be repetitive, and some of them will argue with each other on how to go about certain steps or what order you should do things in, but they're full of useful tips. The handbook I'm using (A Guitar Maker's Manual, Williams, J., 1986) informed me about a little trick to use when gluing rosewood -- because it's a very resinous wood, it's very helpful to wipe the gluing surfaces with acetone. It greatly improves the effectiveness of the glue... but half a dozen other sources I looked at didn't mention this. Now, maybe this trick is completely obvious to a seasoned woodworker, but for someone like me who's never done this before, little hints like this are really helpful.
Picking materials:I highly recommend purchasing all your wood from a supply specifically geared towards instrument making. This way you know the wood has been selected specifically for this purpose -- decent grade, good coloring, correctly cut (e.g. bookmatched pieces for the soundboard and back). I ordered almost everything from LMI, and it looks fantastic. If you don't want to worry about choosing all the individual parts, there are a number of kits out there. The catch is you sacrifice some of the quality control, and there's not as big a selection in woods. But if you're not going for a specific look and you just want an easy way to get started, you may find a kit to be the most convenient solution. I wanted more control over the individual components, so I decided to work from scratch. LMI offered me the best of both worlds, really -- they pre-bent my sides for me, so they arrived already shaped, and I didn't have to mess with the intimidating step of bending them myself. As for choosing one kind of wood over another... a lot of this boils down to personal preferences. I really wanted the darker look of rosewood for the body of the guitar, though mahogany is probably the more common choice for a first guitar. I went with Sitka spruce for my soundboard after researching the properties of a variety of topwoods -- it has a good elasticity and sound travels very quickly in spruce. It was also cheaper than some of the alternatives (like German or Engelmann spruce). See my page of links for some places to shop around. Again, information gathering is key, but in the end, a lot of it will depend on your own sense of aesthetics and the size of your wallet. (Warning: it’s easy to spend a lot of money building a guitar... but you can choose your materials to fit just about any kind of budget. I’m a college student, and therefore poor by definition. I’m building mine for a little over $300, though I have access to a shop on campus and therefore haven’t had the overhead of purchasing tools and scrap lumber.)
Tips in the shop:To take a look at some of the actual process of building my guitar, check out the details of its construction. It may not represent the best way to approach each task, but it will give you an overview of what I’ve done, the problems I’ve faced, and how I’ve gone about solving them. Your wood... try and learn about any peculiarities your chosen woods may have. For example, people can be highly allergic to the dust from the rosewood I’m using. Even though I’m not, I’ve still found the dust to be far more irritating than your average sawdust, and I’ve had to use dust masks whenever I work with it for extended periods of time. Gluing... I’ve been using pieces of scrap wood between the guitar wood and the C-clamps whenever I clamp something while it’s gluing. This keeps the clamps from denting all the nice wood you spent so much money on. :-) Be careful not to let scrap wood get glued to your pieces, though... knocking a stuck scrap off is doable but scary and not worth the trouble. Better to not have the problem in the first place. Take care of your precious soundboard wood and wear gloves as you get to the final stages of sanding! Oils from your fingers can get grime and dirt in the grain and discolor the light wood.
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