Posted on June 23, 2021May 19, 2025 by Dale Phillips Finite Element Simulation of Guitar Top Vibration Finite Element Simulation of Guitar Top Vibration by Phil Banks Originally published in American Lutherie #18, 1989 The use of engineering finite element analysis software to determine modes and natural resonant frequencies of a guitar top can be a useful (albeit lengthy) process which, if used judiciously, can yield useful information to the guitar maker. As a graduate mechanical engineer and a guitar maker, I’ve always been interested in marrying the discipline of the luthier’s craft with that of science. I got that chance last year at the University of Sydney. While working as a programmer developing a Finite Element package, I was asked to produce a demonstration of the program’s capabilities. I decided to analyze a guitar top. Become A Member to Continue Reading This Article This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page. If you are already a member, login for access or contact us to setup your account.
Posted on June 23, 2021May 22, 2025 by Dale Phillips Pre-bending Herringbone Purfling Pre-bending Herringbone Purfling by John Calkin Published online by Guild of American Luthiers, June 2021 Herringbone purfling s a lot easier to work with if it is prebent before it is glued onto the guitar. This is best done after wetting it first. I always use a brush to spread glue on guitars. I keep a coffee cup of water handy at all times, along with an acid brush with the bristles properly trimmed back to the stiffness I like. I dip the brush, then hold it stationary as the strip of purfling is pulled across the cup underneath it. Soak the purfling well on both sides. This should take only seconds. Then the strip is pulled through a dry cloth. Soaking it for too long will encourage it to come apart as it is bent. Give the purfling a minute to absorb the water, then tape the butt end into the channel it will be glued in later. Wrap it carefully around the lower bout using a couple pieces of masking tape to hold it tight. More tape, as well as care, will be necessary to make it conform to the waist area. The wrap around the upper bout should be as easy as the lower bout. In the photo, you can see how much tape was used as well as the small fan used to dry the purfling before gluing it in place. All photos by John Calkin Herringbone will wrap around a moderate Venetian cutaway but do it gently and by stages. To be safe, the purfling can be wet and then sliced lengthwise on one of the glue joints using a single-edge razor blade. On a tight Venetian cutaway, the purfling must be sliced. On this tight-waisted jumbo guitar, the purfling was sliced from the top end to below the waist area to help coax this half-herringbone purfling to conform to the shape of the guitar. Sliced purfling doesn't need to be prebent but you might wish to wet it as you reach that portion of the install. Slicing the purfling can go awry and destroy it. Buy extra. ◆
Posted on May 4, 2020May 16, 2025 by Dale Phillips Free Plate Tuning, Part Two: Violins Free Plate Tuning, Part Two: Violins by Alan Carruth Originally published in American Lutherie #29, 1992 and Big Red Book of American Lutherie Volume Three, 2004 See also, Free Plate Tuning, Part One: Theory by Alan Carruth Free Plate Tuning, Part Three: Guitars by Alan Carruth Before I get into plate tuning proper I’d like to digress a bit and discuss the rationale behind the process, and a couple of other things I find it useful to keep in mind while I’m working. And I can’t think of a better way to begin than by telling you about one of my more elaborate experiments. Fig. 15 gives the relevant information on my fourth and fifth violins. The idea was to check out the influence of asymmetric back graduations by building a pair of closely-matched fiddles with that as the only variable. The one-piece backs were cut from the same plank of bird’s-eye maple and the tops were cut from a red spruce 4×6 that I took out of the wall of my house when I put in a new chimney. The molds were routed using a template. Archings were checked for height at over two dozen points on each plate and were held to .2MM. Graduation, weight, and frequency data is as shown. The delta f mentioned is the frequency drop obtained when a 5G weight was stuck to the plate in an active area of the given mode. Fittings and so on were matched as closely as possible, and the two bridges were cut back to back from the same piece of maple. Become A Member to Continue Reading This Article This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page. If you are already a member, login for access or contact us to setup your account.
Posted on March 13, 2020May 22, 2025 by Dale Phillips Commercial Graphite Acoustic Guitars Commercial Graphite Acoustic Guitars by John A. Decker, Jr. Originally published in American Lutherie #31, 1992 and Big Red Book of American Lutherie, Volume Three, 2004 Why would anyone want to build an acoustic guitar of graphite? The primary reason is that wooden acoustic guitars (particularly good ones) are fragile. They are especially prone to cracking, warping, and joint separation due to heat, humidity, and water. Graphite/epoxy technology — properly employed, which isn’t easy — can maintain the sound quality of a wooden guitar while completely removing its susceptibility to heat and moisture. During the past seven years Kuau Technology has been working with luthiers at the firm of Pimentel & Sons, of Albuquerque, New Mexico, in the development of acoustic guitar technology employing fiber-reinforced resins, particularly graphite/epoxy. Our approach has been to duplicate as closely as possible, panel by panel, the acoustic properties of fine wooden classical guitars, rather than attempt to reinvent the guitar de nova. This work has resulted in the development of the RainSong® Graphite Acoustic Guitars,* which we believe to be the first commercially available all-graphite acoustic guitars. Become A Member to Continue Reading This Article This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page. If you are already a member, login for access or contact us to setup your account.
Posted on March 2, 2020May 16, 2025 by Dale Phillips Free Plate Tuning, Part Three: Guitars Free Plate Tuning, Part Three: Guitars by Alan Carruth Originally published in American Lutherie #30, 1992 and Big Red Book of American Lutherie Volume Three, 2004 See also, Free Plate Tuning, Part One: Theory by Alan Carruth Free Plate Tuning, Part Two: Violins by Alan Carruth The guitar is somewhat simpler acoustically than the violin, and perhaps more limited. As a result it has evolved into a number of more or less specialized forms to suit different musical uses. It is difficult to imagine a guitar that could “do it all” the way a good violin can. Rather, each guitar seems to have a “center,” a sound that is characteristic of it that suits it for a particular style or player. Good guitars do have a wide dynamic and timbral range, but they always retain their characteristic sound. As I see it, a good part of the art in this game is deciding where you want the “center” to be, or, alternatively, how to get the “center” you want out of a given shape or set of wood. And then you want to have a broad dynamic and expressive range, good balance, and clarity or resolution; the ability to distinguish things like inner lines. No amount of acoustic science is going to tell you what priority to put on the different characteristics of the sound, nor whether you have succeeded in the end. But if you know what you’re doing, an oscillator and a jar of glitter can help you get the sound you want. One of the main simplifying factors between the guitar and the violin is the lack of a soundpost in the guitar. This allows the top and the back to be more independent; in acoustic terms they are not so tightly coupled and can act out of phase. Become A Member to Continue Reading This Article This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page. If you are already a member, login for access or contact us to setup your account.
