An Elegant (but simple) Fingerboard Taper Jig

Over the years, I have seen many solutions for precisely cutting the taper of the fingerboard for guitars and other instruments. Most of the solutions involved making either an exact template of the fingerboard shape and using a pattern bit in a router to copy it, or making a table saw sled which allowed the user to line up his/her pencil lines on his fingerboard and cut it with the table saw.

Neither of those solutions appealed to me since both either required making a template (more work) or actually drawing pencil lines on the taper you want (not as accurate as I would like).

Many years ago, I saw a jig which was designed originally to cut tapered legs for a table but seemed to be ideal for instrument use. I have been using this system for ten years or more and it works great! Its' primary advantages are: (1) very simple and easy to make (15 minutes or less),   (2) no measuring and laying out the shape of the fingerboard, (3) no pattern making, and (4) absolute accuracy, meaning the taper is always perpendicular and centered to your fret cuts. In this short article I will attempt to show you the jig, how to make it, and how to use it.

Decide The Taper

The first step you must do is decide on what taper you want. The taper is the difference in the width of the fretboard at the nut and the width of the fretboard at its' widest point (the other end). For instance, on my instruments I use a 9/16" taper. All that really means is I want a nut 1 11/16" and the board to be 2 1/4" at its' widest point. That just happens to give me 2 1/8" at the 14th fret using a 25.4" scale. Doing the math indicates that the taper for that specification is 9/16" (2 1/4" - 1 11/16" = 9/16"). You can make the taper whatever suits you, you just need to know the nut width and the total width of the fretboard in order to make the jig.

 

Making The Jig

The jig itself is just a piece of wood about 5" long (not critical) with two notches cut into it; one end has a 9/16" notch (the full taper) and the other has a 9/32" (1/2 the full taper) notch. You can just simply notch a piece of plywood with the two notches or, to be really accurate you can cut 3 pieces and glue them together to make the jig. The three pieces I used were 9/16" x 5 1/4", 9/32" x 5 1/4", and the center piece was 1 1/8" x 4 3/4". Just glue them together as in the photos. The total width of the jig must be less than the total width of the fingerboard (in our case 2 1/4"). The finished jig has notches in opposite ends that are 1/2" deep although, as you will see in a minute, that too, is not critical.

Using The Jig

This is a table saw jig. One of the beauties of the jig is, that in use, it leaves an edge which is ready for gluing. No touchup or sanding required. Let's begin. Your fingerboard should already be squared and fretted and cut to the correct length.

Set your table saw fence to the total width of the fingerboard. Cut the fingerboard to this width (in our example that width is 2 1/4")(this is why the jig must be less total width than the fingerboard). Lay your jig on the table saw against the fence and set your fretboard with the fret cuts UP and the nut end in the smallest notch which is up against the fence as in the photos. Run it through the table saw.

Flip the fretboard over so the fret slots are on the BOTTOM. Flip the jig around so the largest notch is closest to you and against the fence. Put the flipped fingerboard nut end in the large notch and run through the table saw. Congratulations! You have created a perfectly tapered fingerboard which is perpendicular to your fret slots and ready to use! It will be exactly 2 1/4" wide at the widest point, and 1 11/16" at the nut.

 

Allowing for Binding

One of the real advantages to this method is that you can cut the fingerboard to the correct taper for binding if your binding covers the entire side of the fingerboard. Lets's assume your binding is .090" thick. You have two sides of the board so the total thickness of the binding is .180". Subtract that number from the 2 1/4" (2.250") we started with leaving you a total width (allowing for binding) of 2.070". This time set the fence to 2.070 and repeat the procedure. You will wind up with a perfectly tapered fretboard. Once you glue on the edge binding it will be exactly the same as above (1 11/16" at the nut and 2 1/4" at the far end). No measuring and no touching up!

Summary

This jig allows you to have complete control over all the measurements without having to make any pencil lines and the accompanying errors that creates. Just remember that your nut width is defined by the total width of the fingerboard less the taper your jig allows. This gives you great flexibility in designing and executing your fretboards with a minimum of fuss.

This article was originally written for and published in GUITARMAKER, the quarterly journal of the Association of Stringed Instrument Artisans (ASIA).