Fingerboard Geometry: Project Overview

I am investigating how the fingerboard’s radius, scoop depth along string paths, and scoop along edge interact with one another. In the first phase, this project will use Google Forms to survey makers to find the ranges and averages of dimensions needed to generate the models.

I am studying this because, in my personal experience of shaping fingerboards, I have run into issues reconciling various sets of dimensions and scoop requirements, leading me to wonder how the surface of the fingerboard is modeled theoretically. In arc-based construction, some target dimensions will conflict with one another, and most people end up “fudging” or compromising to achieve their desired balance of playability and aesthetic. My goal here is to solve for a few quantities on the relationships between dimensions that luthiers do actively pay attention to while shaping. I am aiming for results to look something like, “If I put priority on a perfect constant radius and G & E scoop, the D & A scoop will be off target by ___ mm or %.” 

Part 1: Survey dimensions

12/26/2017: The results of the survey are up.

Part 2: Case study models

1/13/2018: Analysis of Scoop vs. Radius relationships is up.

I’ll make models following the most frequent orders of priority rankings, and show how lower priority dimensions are sacrificed for precision of higher priority ones per case.

Model building details (sorry, I didn’t ask for these in the survey!):

  • 24mm nut end width
  • 42mm bridge end width
  • 16mm nut string spacing
  • 30.73mm string spacing at bridge end (projected from a 34mm spacing on a bridge  330mm away from nut)
  • 42mm baseline radius (will calculate exactly what “tighter” and “flatter” are case by case)
  • 270mm length
  • 5mm thick at bridge end (as there will surely be twists in many of the models).

For simplicity (and because many makers use templates of specific radii), I am limiting this study to arcs. All arcs will be drawn from 3 points (i.e. G, middle, and E). I will give you beautiful illustrations of cute 10x squished fingerboards so you can really see what’s going on with those scoops and twists!

fb preview

The image above is from Rhino, but I actually plan to use OnShape (thanks to recommendation by my sister, Dr. Maxine Fontaine) to generate the models for everyone’s viewing pleasure. I will also calculate relationships where possible (as in, have my brother-in-law, Dr. Nick Fontaine, do it with Python for me).

Post script

The point of this study is NOT to tell you what dimensions are right or wrong! (I’m pretty sure that’s your client’s job, haha!) It is just to quantify how the dimensional factors interact.



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