Posted on March 3, 2026March 3, 2026 by Dale Phillips Length of Newt’s Tail by Width of Dragon’s Hair Length of Newt’s Tail by Width of Dragon’s Hair by Ken Sribnick Originally published in American Lutherie #55, 1998 Don’t hurt me. I’m going to tell you an old joke. How many luthiers does it take to split a dragon’s hair? One to split the hair, and the rest to say, “Oh, that’s how you do it.” At our 1995 convention, I heard a number of luthiers ask about measurement and precision: How do you check this? When is that flat enough? In the spirit of the little joke, I thought it might be interesting to tell you my approach. These surely aren’t the only, or necessarily the best, methods — only how one man splits dragon hair and newt’s tail in our little shop. My early lutherie and repair went slowly until an experienced luthier, a repairman in New York’s music district, helped me along. His “luthier’s gold” included explaining which measuring tools to have, and how to use them. Consistency is essential. You must strive to reduce error and deviation. To this end I have “master” reference tools in the shop: one ruler, one caliper, one flat surface, and my drawings. It doesn't matter if you use metric measurements or inches. Just pick the system you’re comfortable with, have good master references, and, stick with them. You’ll be successful. I’m metric because I tune Toyotas as well as 12-strings. Become A Member to Continue Reading This Article This article is part of the Articles Online featured on our website for Guild members. To view this and other web articles, join the Guild of American Luthiers. For details, visit the membership page. MEMBERS: login for access or contact us to setup your account.
Posted on January 19, 2026February 23, 2026 by Dale Phillips Calculating Fret Intervals with Spreadsheet Software Calculating Fret Intervals with Spreadsheet Software by Wayne Kelly Originally published in American Lutherie #43, 1994 Luthiers who own or have access to a personal computer will find spreadsheet software useful in calculating fret intervals. Spreadsheet software is commonly used for accounting, budgeting, and presentation of tabular data. It is invaluable for testing “what if” scenarios because a change made to one cell of a spreadsheet will cause a “ripple effect,” automatically changing values in other cells dependent on that cell. This feature of spreadsheet software makes it possible to calculate fret intervals for a given scale length instantly. Change the scale length value and “presto,” another set of fret intervals is automatically and instantly calculated and displayed. Results can be printed if desired. Within a few minutes one could create a book of fret interval tables for dozens of different scale lengths. I created a spreadsheet to calculate fret intervals using the “fret factors” found in a popular textbook on guitar building (Cumpiano, William R. and Natelson, Jonathan D., Guitarmaking: Tradition and Technology, Rosewood Press, Maine, 1987, p. 268). With fret factors, each fret’s distance from the nut is determined by simply multiplying the fret’s factor by the chosen scale length. My spreadsheet allows one to enter a given scale length, expressed in decimal inches, and it then calculates and displays the distance from the nut to each of 21 frets, as shown in the accompanying figure. The fret intervals are displayed in three columns expressed in centimeters, decimal inches, and sixty-fourths of an inch, respectively. Become A Member to Continue Reading This Article This article is part of the Articles Online featured on our website for Guild members. To view this and other web articles, join the Guild of American Luthiers. For details, visit the membership page. MEMBERS: login for access or contact us to setup your account.
Posted on October 10, 2025October 10, 2025 by Dale Phillips Derivation of Formula for High Point of Back Derivation of Formula for High Point of Back by Jon Sevy Originally published in American Lutherie #75, 2003 and Big Red Book of American Lutherie Volume Seven, 2015 Quantities: S = height of guitar sides at neck block B = height of guitar sides at end block E = B - S (difference in height at shoulders and butt) L = length of guitar body A = length of body measured at angle (see diagram) D = deflection in arched back (see diagram) R = radius of back arch Become A Member to Continue Reading This Article This article is part of the Articles Online featured on our website for Guild members. To view this and other web articles, join the Guild of American Luthiers. For details, visit the membership page. MEMBERS: login for access or contact us to setup your account.
Posted on October 9, 2025October 9, 2025 by Dale Phillips Calculating Guitar Side Height Calculating Guitar Side Height by Mike Doolin Originally published in American Lutherie #75, 2003 and Big Red Book of American Lutherie Volume Seven, 2015 Back in American Lutherie #58 (Big Red Book of American Lutherie Volume Five), Jon Sevy published the article “Calculating Arc Parameters” which described how to calculate the radius, length, or depth of a curve. I’ve used these formulae extensively ever since for radiusing fretboards, making dished workboards, calculating neck angles, and even nonlutherie shop tasks. Recently it occurred to me that one could use them to calculate the height of a guitar’s side at any point. If the guitar has a spherically domed back, the back falls off from its highest point in an arc in every direction, as in the photo. This “high point” is effectively the North Pole of the sphere from which the back arch is taken. If we assume a top whose perimeter is all in the same plane, as in Fig. 1, that plane intersects a line of latitude on that sphere. The high point is therefore the point on the back which is farthest from the plane of the top perimeter. All measurements of side height are then distances between that plane and the surface of the sphere of the back arch. I adapted Jon’s formula to calculate the falloff from the high point on the back to any point on the side: Become A Member to Continue Reading This Article This article is part of the Articles Online featured on our website for Guild members. To view this and other web articles, join the Guild of American Luthiers. For details, visit the membership page. MEMBERS: login for access or contact us to setup your account.
Posted on June 21, 2025September 15, 2025 by Dale Phillips The Helmholtz Resonance The Helmholtz Resonance A Brief and Not-Too-Technical Introduction to the History and Theory of the Lowest Sound-Producing Mode, and Some Practical Considerations for Instrument Designers by R.M. Mottola Originally published in American Lutherie #82, 2005 and Big Red Book of American Lutherie Volume Seven, 2015 Research in physics and acoustics of stringed instruments shows us the mechanism by which sound is produced by those instruments. The plates of the instruments and the air inside vibrate in various patterns, each pattern producing sound in a range around a certain frequency. Each of these patterns can be considered to be a resonator, each with its own characteristics. Some of these resonators exist as modes of vibration of different areas of the plates of an instrument, and some are modes of vibration of the air inside the instrument. One of the air resonators is composed of the mass of air inside the instrument and the mass of air within and around the soundhole. The natural frequency of this resonator is near the lowest note that an instrument can make. It is generally labeled the A0 resonance, the letter A standing for the word “air” and the numeral 0 indicating that this is the first in a series of air resonances. This resonance is also referred to as the so-called Helmholtz resonance. Understanding how this resonance works in stringed instruments is not difficult, particularly given a historical perspective. Complete understanding involves some math, but a practical understanding can be had without it. Therefore, I am putting off presenting the formulae in the main article and have included them in a sidebar. Become A Member to Continue Reading This Article This article is part of the Articles Online featured on our website for Guild members. To view this and other web articles, join the Guild of American Luthiers. For details, visit the membership page. MEMBERS: login for access or contact us to setup your account.
