Not Only Cones Make It — and Cylinders Almost Do

by F.A. Jaén

Originally published in American Lutherie #101, 2010



In the years since Tim Olsen’s article “Cylinders Don’t Make It” appeared in AL#8 (Winter 1986; also BRBAL1) the main ideas presented there have been accepted, developed, and finally, simplified and distorted. Many, including myself, remembered it more like “Only Cones Make It.”

The first indication that something in my ideas was wrong was when I made a CAD model of a fretboard some time ago. I wanted it to have a constant curvature radius of 300MM (around 12"). There are many customers that still want that, in spite of offering well-designed conical-shaped fingerboards. My first thought was to draw two circles, 12" diameter, one directly above the other, at the distance from nut to end. After that, I would trace two diverging straight lines connecting both circles and defining both the edges of the fretboard and the widths at its ends. The surface could then be generated by moving one of the edge lines towards the other, using the end circles as rail curves (what is known as a “sweep” command in many CAD packages).