Building an Acoustic Steel-String Guitar
Thirty-eight year Guild member Jon Sevy builds acoustic and electric guitars. He is a former college math professor who currently supports his lutherie habit with a day job as an embedded software engineer.
▪ bio current as of 2023
2023
AL#149 p.58
Jon Sevy
▪ A couple of cheap gizmos from Harbor Freight can be cobbled together to let you measure the thickness of the sides or plates of an assembled guitar.
2021
AL#144 p.52
Jon Sevy
▪ If you are cutting pearl inlays with a benchtop CNC router, then cutting the recesses for them with that same CNC, they ought to fit perfectly, right? Well yes, in the perfect world of math. And even out here in the messy real world of sawdust and bearing slop, you can get pretty close if you understand the forces at play and calculate their effects.
2021
AL#143 p.71
Jon Sevy
▪ Little rare-earth button magnets are cheap. Sevy cleverly recesses them into a peghead face to hold the truss rod cover in place with no screws. He figures the cover is less likely to be misplaced by the guitar’s owner if they don’t need to use a screw driver to put it back on.
2010
AL#104 p.69
Jon Sevy
▪ The relationship between the familiar 17.817 fret spacing constant and the 12th root of 2 is demonstrated.
2005
AL#81 p.36 BRB7 p.296
Jon Sevy
▪ All those cool pre-war Martins not withstanding, many luthiers believe that domed guitar tops are the way to go. But they can complicate construction in unforeseen ways. Sevy offers a mathematical cure, a set of formulas for predicting neck pitch and saddle height. Probably not for the math challenged, but give it a look before you abandon this path. With 4 charts and 5 diagrams.
2003
AL#75 p.40 BRB7 p.98
Jon Sevy
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2003
AL#73 p.36 BRB7 p.14
Jon Sevy
▪ This piece is aptly subtitled “Rules of thumb for approximating changes in the size of braces, tops, and strings,” which sums it up nicely. Our teachers promised us that math wouldn’t be irrelevant in our futures, and here their words come back to bite us. Sevy obviously believed them, and here presents some “easy” formulas for calculating the results of changes in size we might make in our instruments.
1999
AL#58 p.42 BRB5 p.355
Jon Sevy
▪ If first-year college math pushed your left-brain functions to the limit (been there, done that) you may cringe at the sight of the simplest equation. If so, check out this article. Modern luthiers build arcs into many of their instruments, and if you don’t know how to create them to lay out your own jigs you’ll be forever at the mercy of tool suppliers. Worse yet, when someone asks what the radius of your back plate is you can shrug your shoulders and look like an idiot. Let Sevy solve your problem. You can do it!
1998
AL#56 p.3
Jon Sevy
▪ Sevy has developed a spreadsheet for calculating the over-all time spent building a lutherie project. He offers the spreadsheet to readers through his website.