August 2016 | Benchpress Newsletter

19th AMENDMENT


The guitar is an incredibly versatile instrument in its standard form. Even routine requests for hardware and pickup swaps produce an endless range in the tone and playability of an instrument.
On occasion, folks want something decidedly non-standard such as adding extra pick ups or cutting off parts of the guitar body to make it look like an oud. Even within the range of non-standard projects, most players never question the 12 tone scale. This scale is the one we're most familiar with in Western music. Recently a customer came in with such a request.

Chris brought in an Epiphone, left to him after a friend passed away, to see if we could change the scale to a 19 tone equal temperament.

The 19 tone equal temperament tuning breaks the octave into 19 parts, each equal on a logarithmic scale. Of course his guitar was fretted for a 12 tone scale, which breaks the octave into 12 parts. I am no expert on the theory behind this, but I do know how to solve guitar problems, so here’s what we came up with.

To get the scale change started, we needed a fingerboard with no fret slots. The two options were 1) the guitar would need to have its existing frets pulled and the fret slots filled or 2) plane off the existing fingerboard then glue on a new fingerboard. We decided the second option was the way to go since we could precisely cut the new fret slots and the end result would be visually flawless.

To do this, Tomm used the Plek to plane off the old fingerboard then glued on a new board. After that he trued it to the neck shaft and touched up the finish on the edge. When it was finished, you couldn’t tell the fingerboard had been replaced.
Now the challenge was to cut the 19 tone fret slots. When slotting a fingerboard, there’s nothing more accurate than the Plek, but its slotting plug-in is limited to a 12 tone instrument. We could have manually slotted it, but we wanted absolute accuracy and elegant pocketed fret slots, so we gave Plek a call to see if there were any options. Nick at Plek said he could write an engraving program to engrave slots at the desired distance from the nut. Using an online calculator, Geoff calculated the proper measurements and gave them to Nick. Voila, the Plek cut the proper number of pocketed fret slots for the 19 tone scale.
The next step was to install and level the frets. The only difference in fretting a 19 tone vs 12 tone is that there are more frets. After the frets were pressed into the board, they were leveled and the ends were beveled. Since the Plek isn’t able to level frets outside of the 12 tone range, we had to go old school. Tomm dusted off the neck jig and did a manual fret-level. Once it was strung up, he put it through its paces and it played and sounded great.
Chris was very happy with the end result, as were we. To learn more about 19 tone equal temperament, check out this Wikipedia page. There are some amazing pieces on YouTube here, from classical guitar to drum and bass.