At some point in the life of any gut fretted instrument, there will come a day when worn or loose
frets will start causing problems. While I am happy to sort out fret problems on all my instruments, indeed
I encourage new owners of my instruments bring them back to me after 6 months so I can refret them and
check for any other problems, it is not always practical for a player to bring the instrument to the
maker to do this maintenance work.
It is, however, quite possible for owners to sort out their own frets with a little practice and patience.
For those that want to have a go at refreting, what follows is my method of tying gut frets. There are many different ways of doing this, but this is the method I use. It has the advantage of producing a small knot that, if positioned correctly, will not be too obtrusive.
I use a system of, so called, graded frets. That is the diameter of the gut used for the frets decreases as you go down the neck towards the body. This, combined with the correct neck angle and fingerboard relief, enables me to achieve a low action without too much risk of strings buzzing on the next fret when played hard.
When my new instruments are delivered they are provided with tables of the fret diameters used and the positions they should be in. For those starting a refret from scratch I have included some details of how to calculate frets positions in equal temperament.
My tuner program includes a rudimentary fret position calculator which is capable of producing unequally tempered fret positions.
Tools you should have to hand
You should also have fret gut in a range of diameters available. This will usually start around 1mm and end up around 0.5mm.
Suppliers of strings usually also carry fret gut. See the links page.
Frets should be tied with all the strings on and the instrument should be up to pitch.
The size of the first fret will usually be around 1mm on my instruments. The exact gauge used will be listed on the fret sheet that was supplied with the instrument. If you have not got a list of frets for your instrument, you can always measure an unworn part of the existing fret using a micrometer or vernier callipers.
Start with the instrument on a flat soft surface with the neck towards you, the body away from you. To tie the fret, thread a length of new gut under the strings from treble to bass. Bring the rest of the gut under the neck to the bass side. Let the end that emerges from under the strings be called the 'short end'. The rest of the gut is the 'long end'.
Tie the knot, a simple 'granny', with the short end, around the long end. If you start by having the short end further down the neck than the long end and pass the short end under the long end towards yourself, you should find that the knot, when tightened, will lie flattish against the corner of the fingerboard.
Using pliers, tighten the knot as tight as you can get it, then using clippers cut of the short end to leave about 2-3mm beyond the knot.
Using your lighter, bring the flame, carefully, just close enough to the short to singe it until a small blob forms close up to the knot. Be sure not to burn your strings, hands or anything else other that the fret gut. Some people prefer to use a small electric soldering iron for this.
Please Note when pulling the fret tight it sometimes happens, especially with the thinner gut sizes, that the knot can pull through suddenly causing a big jolt. It is therefore important not to have anything hard or sharp in the way that could damage you or your instrument if this happens.
Now tighten the fret by pulling the long end, use the pliers if there is not enough to get hold of. If the knot was tight enough and the blob formed correctly, you should find that the fret kind of 'locks' as it gets tight. With the thicker fret, you need to get the fret as tight as you can at the narrowest part of the neck that is available. If it is the first fret, this will be just beyond the nut, otherwise just in front of the previous fret. With thinner frets (less than 0.6mm) there is much more elasticity so you will not need to put in so much force to get them tight.
Trim back the long end to leave 2-3mm as with the short end.
Burn this free end back as before and slide the fret up the neck into its right position. If yo have got the fret tight enough this should be quite difficult. Remember that over time the gut will stretch and loosen, so the tighter the better now.
|For those interested in the maths...
A basic formula for dividing a vibrating string into equal semitones is..
F=S/17.817Where F is the distance of the fret from the nut or the previous fret and S is the remaining vibrating string length.
This is often called the 18 rule, because the dividing constant, 17.817, was approximated at 18
String length=600mm First fret =600/17.817 =33.7mm Remaining string length =600-33.7 =566.3mm 2nd fret =566.3/17.817 =31.8mm that is 31.8+33.7 =65.5mm from nut etc...I have worked this example to a 10th of a mm, but in practice you will be hard pressed to position your frets any more acurately than 0.5mm. In any case, differences in finger pressure, string thickness etc. probably make have more efect than the odd 10th mm .
Since this is a sequential method, i.e. the result of the first calculation is used in the next, there is the possibility of compounding any errors. With this in mind there are checks that can be made along the way. The 12th fret should be at half the string length. The 5th fret should be approx.' a quarter of the string length. Also remember that having movable frets, it is very easy to tweak them into whatever position suits you and your instrument. Action heigths and string materials will all make a difference.
For those who are intereted in temperaments, read on.
Here we divide the octave into 1200 equal cents rather than 12 equal semitones. I will not go into the reasons and theory of unequal temperaments here since it is a complex subject and others have already explained it better than I ever could. The formula below will give the position of a fret to give a certain cents interval. Thus if you know the cents values of the temperament you are working with, you can use it to tell you where your frets should be in theory. Of course all attempts at unequal temperaments on fretted instruments are approximations but the are worth experimenting with. I often use 1/6th comma meantone on my 6 course lute. My tuner program implements the formula below in a graphical way to give a diagram that shows both equal and unequal tempered frets.
constant K =(ln(A/2)-ln(A)/1200 =-0.69315/1200 =-0.00058 Fret Pos =S*(1-exp(cents*K)) Example: string length S=600mm 5th fret equal temperement is 500 cents Fret pos =600*(1-exp(500*K)) =600*0.25 =150.5