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Measuring Archtop Musical Instruments

Measuring Archtop Musical Instruments

by Chris Burt

Originally published in American Lutherie #83, 2005

See also,
Arched Plate Carving, Part One by Chris Burt
Arched Plate Carving, Part Two by Chris Burt
Arched Plate Carving, Part Three by Chris Burt


This is the first of three articles that take you from the basics of creating your own database of musical instrument measurements to applying what you have learned from those measured instruments while you carve top and back plates. In this article, you will learn to safely measure fine instruments. Article Two will describe plate carving, and article Three will describe plate graduating.

This article is dedicated to Bob Lundberg, from whom I first learned the basics of measuring instruments. He showed us how to set the bar high. — Chris Burt

Before you can build an archtop instrument based on an existing model, you need templates — at a minimum: a body-shape template, neck cross-section templates, and plate arching templates. You can’t carve something if you don’t understand it. If you are going to spend the considerable time that’s required to understand an instrument model, seek out the best. Measure several and keep detailed notes. If you take the time to compile a set of measuring tools and learn to use them respectfully and gently, you’ll be surprised to find how many people will allow you access to their fine instruments.

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Chalk-fitting Guitar Braces

Chalk-fitting Guitar Braces

by Stephen Marchione

from his 2017 GAL Convention workshop

Originally published in American Lutherie #140, 2020



First, have a plan. Know what you’re making. It seems like an obvious thing, but sometimes people start a guitar without a good idea of what the brace layout will be. When I design a new model, I’ll often get a piece of aluminum flashing and lay out a bracing template. If you’re building an historical model, you can transfer the blueprint to a template of aluminum or plexiglas. This gives you a clear idea of what your braces are supposed to be doing, and it lets you be sure that the braces end up where they were designed to go. Photo 1 is a closeup of one of my bracing templates. I use the little holes to make pencil marks on the soundboard.

On a classical guitar, a lot of builders push the big harmonic bars down into the solera, or dished workboard. But that can cause distortion of the top. Even on a Spanish guitar, I take the time to chalk-fit the brace. That gives a better structure with less stress. I highly recommend it.

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Questions: Single Fretting Fixture

Questions: Single Fretting Fixture

by Tim Shaw

Originally published in American Lutherie #101, 2010



Mark French from West Lafayette, Indiana asks: Do people ever make a single fretting fixture and just pick off whatever section they need for a specific type of instrument? I started with a 25.5" scale length and added some frets to bump it up to about 34.07". It looks like I can use this set of positions to find fret spacing for everything from a bass to a mandolin.


Tim Shaw from Fender in Nashville, Tennessee responds:

You could also use this for both medium-scale bass, which is usually 32", and short-scale bass, which is typically 30" or so. Since Leo Fender had the 25.5" scale first, I don’t know if he actually “added” frets to come up with 34", but that was certainly possible on the prototype. The shorter Fender scales were also probably started by lopping frets off a standard neck.

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Mechanical Compliance for Soundboard Optimization

Mechanical Compliance for Soundboard Optimization

by David Hurd

from his 2006 GAL Convention workshop

Originally published in American Lutherie #90, 2007



People say, “You’ve got to make fifty or a hundred guitars before you get it right.” That makes me crazy. I feel that if you can do the carpentry of putting an instrument together and have idea of what it should look like, you can get 80% or 90% of the way there in terms of top optimization with a mechanical compliance approach.

I build many sizes of guitars and ukuleles using different top woods. I have developed an easy method of testing the compliance of a top, that is, how far it flexes under a given force, with a simple fixture. Being able to measure and compare the compliance values has proved to be a very useful thing in optimizing these soundboards for the best sound and stability when I graduate the edges of the tops and carve the braces.

After building and measuring many instruments, I have developed a mathematical model that does a very good job of estimating what the target compliance measurements should be for a given instrument size and string tension. I have integrated the model into a spreadsheet which you can use by plugging in just a few simple measurements.

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The MacRostie Mandolin Deflection Jig

The MacRostie Mandolin Deflection Jig

by Don MacRostie

from his 2004 GAL Convention workshop

Originally published in American Lutherie #94, 2008



The mandolin world is small enough that if you’re even thinking about building one, you probably already know who Don MacRostie is. Don is an inventor, and he’s done more for Stewart-MacDonald than we will ever hear about. He’s been making Red Diamond mandolins for two decades now. At the 2004 GAL Convention Don discussed one of his research tools and told us how he applies it to his construction process to make the sound of his finished instruments more consistent and predictable.

— John Calkin


At the GAL Convention in 2001, Charles Fox floated the idea of teaching a mandolin building class at his American School of Lutherie. As a result, I taught a two week class, building A-style mandolins from scratch. The only thing we started with was thickly precarved oversize tops and backs. Everything else we made totally from scratch. It was a great experience.

Peggy Stuart, a student in the class, documented the experience in a series of American Lutherie articles (AL#75–AL#79). Tim Olsen asked me to demonstrate and explain the plate-deflection machine we used in the class at this convention, so that’s why we’re all here.

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