When you settle into your favorite chair with an acoustic guitar, have you ever wondered just how it came together? The acoustic guitar is a seemingly simple instrument, but the process of building it, whether by one person or in a factory, is complex. Here’s a quick tour of the how a guitar is made.
A guitar builder or luthier’s work starts with wood selection. Different types of hardwood are used for the top, back and sides, neck, and fretboard. Each has certain flexibility, appearance, and sonic properties. They are bent, thinned, trimmed, or carved to suit their functions. Then, assembly begins.
The gracefully bent sides go into a mold. Mahogany blocks are glued at the neck and tail ends. A lining of kerfed mahogany or cedar is glued to the top and back edge of each side to add strength and provide a gluing platform for the top and back, completing the foundation of the body.
Next, the two sides of the top are glued together, and the top is thinned to about one-tenth of an inch. The rosette is added and the sound hole cut. The top of a guitar is normally a lighter hardwood to allow vibration. Spruces, cedar, redwood, and cypress are standard choices, chosen for specific tonal qualities. The top must be both flexible and strong, acting as a speaker membrane, but also able to withstand about 150 foot-pounds of string tension. Bracing is added in carefully selected positions and trimmed. The top is then glued to the body.
At this point, the builder has an opportunity to “tune” the body of the instrument. He removes the body from the mold. Tapping on certain points of the top, and listening with an experienced ear, he carves the braces in certain ways to try to achieve a specific tonality. It is the success of this step that often distinguishes an outstanding instrument from one that is “almost” perfect.
Having “tap-tuned” the body, the next step is to add the back. The two halves of the back are joined and braced. The braces are shaped, but not as exactingly as those on the top, and the back is glued on. With a power router, the builder now cuts channels for the binding and purfling, the decorative and protective strips of contrasting hardwoods or plastic that rim the back and top of the guitar. After they are glued on, the body is essentially complete.
Next, a mahogany or maple neck is carved, and an adjustable metal truss rod is inserted. The fretboard, of ebony or rosewood, is made with a slightly curved top. Fret slots are cut at exact locations, and frets are added.
The attachment of the neck to the body must be done to exacting specifications so that, when the bridge and saddle are installed, the strings will be close to the height needed. Only slight adjustments can be made after the guitar is completed. The bridge is glued to the top within a few thousandths of an inch of the absolutely perfect position. The saddle is painstakingly hand shaped and inserted. Frets are leveled and polished, and tuners are installed on the headstock.
Now, the detailed process of finishing can begin. Using lacquers, oils, shellacs, or other materials, the builder painstakingly creates the smooth, glossy surface you expect on an acoustic guitar. This step may take a month.
For any builder, stringing up a newly completed guitar is always a thrill. After months of detailed work, the new instrument sings out, its voice unique among all guitars.
Strumming it, feeling its vibration, hearing the sweet sustained trebles, knowing it will be enjoyed, is a luthier’s greatest reward.
More information on building a guitar can be found in Bill Cory’s book Complete Guide to Building Kit Acoustic Guitars (EADGBE PUBLISHING) AVAILABLE AT WWW.KITGUITARMANUALS.COM.