RETROFRETTING FOR NON-TWELVE SCALES
By BUZZ KIMBALL (revised 2003)
EXCLUSIVE FOR NONOCTAVE.COM
“Refretting a stringed instrument is one of the easier
ways of getting into experimenting with a non-standard scale. In this
way the curious (adventurer), or those bored with the same old tired
twelve tone clichés, can make an end-run and neatly evade the
built-in sonic limitations of the typical factory product.”
More than a few years have passed since I penned those words in
1987. And since that time, I have experimented much, furthering work
in adapting microtonal guitars for increasing their playability, as
well as building a number of instruments from scratch.
A few special tools are required. There are a number of expensive
specialized tools used by factories and guitar technicians —
such as a fret bender to curve the fret wire, and a fret arbor press
which seats a fret, as well as special fret saws and fret files. But
for the serious experimenter there is a low cost alternative. The most
important is a kerf saw (a kerf is a slot in the fingerboard which
holds the tang of a fret). I usually use a jeweler’s saw, which
can be found in larger hardware saws. Pick up some extra medium
blades as they don’t last long. A decent 10 or 12 inch mill
file, or even a sharpening stone is needed to level the frets after
they are in place. I use a Thomas-Ginex fret refinishing/polishing kit
and garnet paper for a final finishing and burr removal on filed level
frets. Also, a small ball-peen, or tack hammer is preferable over a
carpenter’s hammer. And lots of clamps, of course.
Simply put, you cut new kerfs for the new frets, plue some epoxy on
the tang and bottom of the fret. Bang it in and clamp it down till
the epoxy sets!
REMOVING THE OLD FRETS AND PREPARING FOR THE NEW
Assuming you have selected an instrument to work on, decided on a
scale to refret to, and have a table for your string length, now is a
good time to pull out the old frets (detwelvulation). Running a
single edge razor or carpet knife between the metal and wood will
reduce chipping. Prying frets without marring the fingerboard is
impossible, but it helps later if you avoid gouges. A fence pliers
helps after the end of a fret has been pried up.
After all the frets have been pulled out it is time for putty and
sand paper. Fill all the old fret slots will wood dough or plastic
wood. After it has hardened but not totally dried— sand. This
gives a new smooth fingerboard and works wood particles into the wood
dough, giving enough color to hide the old slots.
A perfectionist can replace the fingerboard instead. Just a bit of
heat and they pry right off. But there is a bit involved in replacing
Mark out the new kerf, in accordance with your chosen intonation
system and the appropriate fret table. To do this, measure out and
mark on both sides of the fingerboard, then draw lines across.
You’ll get a decent kerf and double-check of the measurements at
the same time.
Once in a while, a new kerf will be extremely close to an old kerf.
In such a case, one has to decide whether to shift the positions of
the fret, or use lots of glue. Even if there is a small space between
the new kerf and an old one there may be a problem: sometimes a strip
of fingerboard a millimeter wide or more between a new and an old kerf
will break away. Filling with five minute epoxy is a good cure.
PUTTING IN NEW FRETS
I choose to use 12 hour epoxy and glue in the frets. This seems
easiest and because the frets stay in despite abuse and both
microtonal and just intonation fretting schemes require a bit of
attention to get a decent action without fret buzz. With closer fret
spacing than the factory 12 equal the tolerances get smaller.
The easiest and most uniform method I’ve found is to cut a
fret with an extra half inch or so, and then hammer the tang of the
fret into the kerf, allowing some of the fret to protude on either
side. Generally, I clamp the frets down to insure a tight solid fit.
Puttin a board on either side of the neck and then clamping ensures an
even distribution of pressure. Inserting six to 12 twelve frets each
evening means fewer clamps are needed. Quick drying epoxy is better
for ex post facto individual fret repairs. After the glue has dried I
use the jewlers saw to trim off the excess fret. Then the edges of
the fret may be rounded and shaped with a file or dremel tool.
LEVELING AND ADJUSTING
Then I use a file to level the surface of all the frets. It gets
rid of all the high spots, which is important, since the tolerances
are tighter than typical. At this point I polish the frets with the
aforementioned commercial polishing tool which has 2 ribs on it to
push garnet paper down so it removes the sharp edges.
At this point the lowest string height is adjusted. This is a
matter of trial and error. With a larger number of frets per octave,
the tolerances mean that the action tends to be higher... but a proper
leveling will nearly compensate for that. A small, flat Swiss file
will help readjust the height of a fret or frets under a particular
string. Sometimes the small file will take care of it; sometimes the
frets need to be polished again.
My experience is that a guitar will grow and shrink with the
temperature and the humidity, so there really is never a
I can not overemphasize the importance of experimenting. Placing a
fret or two in a practice piece of scrap wood, etc. While refretting
doesn’t require a lot of manual dexterity, it is time intensive
and patience is a requirement. Being realistic, my descriptions are
brief. And in any modification/building process you ought to take any
and all advice from any source with a certain amount of caution. The
process is not absolute, and I have only described a process for the
experimenter, outside of any factory, to modify an existing stringed
instrument and ensure that it will be playable for a long time.
After having gotten a Baglama Saz and eventually a fixer-upper
sitar to study and learn existing world just-intonation scales (that
and there were/are a lot of silly theorists touting their ultimate
‘this or that’ scale, entirely on paper, which only
compounds the practical intonation problem), I started building guitar
necks without any of the western taper, actually rectangular — much
as it seems most non-western instruments utilize. At one point, I
built a 19et and 31et in this style, as I had converted one 19 and two
31 guitars with factory necks to 5 string guitars. This was one way
of easing the cramping of the microtonal frettings. But it means a
new bridge, nut, and tailpiece need to be fabricated. Even so,
I’ve found the 5 string conversions to be pretty slick.
At some juncture one might hesitate to decide on a new fretting
scheme for a suitable standard guitar. The major 3rd between the G &
B strings creates a huge problem in just tunings. Especially, as a
just 5 limit major 5/4 is usually utilized where a nominally
Pythagorean 3rd is used in the 12 tone scheme. This messy problem lead
me to choose the microtonal temperaments, in particular, I recommend
(as Ivor Darreg did in his Feb. 1978 Guitar Player magazine
article) 19, 22, 31, 17, and 34 equal temperament, in that order.
I’ve also tried, but abandoned 18, 24, and 29et as not to my
tastes and also abandoned 41 and 43et guitars as too nasty
mechanically and not particuarlly different sounding from 31 and 34et.
Others have fretted from nine to fifty-three tones,
and nearly all places in between, for various reasons. And some might
consider a meantone, or partially tempered scale, as was common in the
early European tradition. My only experience with a just scale on a
six string guitar is with a guitar I converted to return a favor to a
friend, with a Rankin Fingerboard Kit. And, apparently he
settled with an Open D tuning for his personal just intonation
scale which had full frets.
My own just intonation guitars are based on my experiences with the
sitar and bagalama-saz. Two early efforts have only four strings and
use the “ethnic tuning” as I call it of octaves and
fourths or fifths (although that is a simplistic description of ethnic
‘tunings'). In my much later Atlantis series I use four
strings tuned in fifths. Thus so far, I’ve avoided split frets.
A final hint: When converting an old guitar, the “active
string length” to use in calculations is actually twice the
length from the nut to the ‘octave’ note on the string,
which due to the deflection of stopping, will be, perhaps, 5mm less
the the length of the ‘open’ string measurement, or nut to
At this time, I’ve stopped using fretting tables and have
been using the calculators available on-line at the EMI website, as
well as my own basic just intonation calculator. Plus there are a
number of other things to check out.
EMI — experimental musical instruments
- EMI Tools: Utilities for Musical Instrument Makers
- FretFind2D, a two dimensional fretboard design tool
Some other experimenters:
- Adventures in Just Intonation Guitar
- Microtonal Guitar FAQ
Last but not least,
- A Justly-Tuned Guitar
© 2003 Buzz Kimball