How to Tie Gut Frets
Don’t let the idea of tying your own frets frighten you, it’s quite a simple process. My aim is to provide the best images possible here so that you can see what you are doing in this process which should only take a few minutes at most. You’ll need:
New frets
A lighter
A crochet hook
End nippers
A piece of wood that fits in your palm
Step One - Nip off the old fret with the end nippers by clipping off the knot.
Next, use a crochet hook or similar tool to remove the bass strings from their slot and away from the edge. No need to detune your instrument.
You’ll need new fretgut. I like the Varnished gut from Gamut Strings. Your first fret will typically be of the 1.00mm gauge. Each successive fret will be .05mm smaller. This is how we adjust our action, using different gauges where required! Using all the same gauges will likely create buzzes. So they go in order of largest to smallest as so: 1.00mm, .95mm, .90mm, .85mm and so on.
Holding the end of the gut at a 45 degree angle and the lighter similarly opposed, use the blue bottom of the flame to heat the end of the gut until it fizzles and mushrooms.
Now tie the simplest of overhand knots in the end of the gut as pictured above. You’ll want the mushroomed end near the circular knot as this is ultimately what holds the fret tension once things are pulled tight.
You’re going to tie each fret lower on the neck than it will ultimately end up. Because the neck widens toward the higher frets, moving the tied fret from a lower to a higher position creates a wedging action that pulls the fret nice and tight. Each fret will be tied about 1.5 inches lower than its final position. Need more tension? Simply tie lower. The 1st fret being the exception as the nut gets in the way. Thus the small divets that can be lightly sanded in the fretboard surface to shorten the cirumference in one spot — a great place to tie number one fret. Now, pass the untied end of the gut under the strings. Note that nothing has been trimmed yet — you want to keep that long piece of gut intact for pulling in a sec.
Pass the long, untied end through the loop of the knot so that both loose ends are aligned and pointing in the same direction. Pull the loose end through now to remove most of the slack.
Now we have this. But see how loose that knot is? We need to tighten that up so our mushroomed ends hold firm and don’t slip through. You can use your fingernails if you want, but it helps that the long end now be put under tension. Note again how far below the fret’s final position the fret is being tied on the neck. The distance will be greater for the higher frets.
Wrap the long end of the gut around a piece of wood like so, and pull everything tight, holding the neck firm, your grip on the neck being near the area of the fret being tied.
With one hand gripping the neck near the fret we are working on, and the other pulling the free end of the gut, pull tightly, moving the free end up and down, back and forth until we get that knot to tighten up. Use your fingernails if you have to to get that knot tight, but eventually it should close up and grip the free end tightly all by itself. Do not pass to the next step until this knot holds tight when you let go of the loose end. The heavy gauge (1.00mm) is the toughest to get tight, the others are increasingly easy.
When your knot is properly tight, the fret will remain under tension while you nip off the end with just about 2-3mm of extra gut hanging free. Next we will mushroom this end as well.
See how the fretboard is angled down, away from the heat of the flame, and the heat of the flame can only rise? This is how you hold the instrument, angled like so, while again you use the blue bottom of the lighter flame to fizzle and mushroom that last free end of the fret. Mushroom it until it sits tight against the knot, and then mushroom it just a little bit more. As the mushroomed end gets nestled into the knot, it will cease to fizzle as quickly, and then you know there is no free end left that can pull through and loosen.
Let things rest for about a minute and then get out your tuner. I use Peterson iStroboSoft as it is without a doubt the most precise digital strobe tuner. Slowly move the new fret into position, testing every so often to see when the fretted note rings as near to zero cents (your open string should ring similarly close to zero cents) as possible. Do this on the bass, then the treble side, fine tuning as you need to (a fret that is too high on the neck yields sharp/positive cents; too low on the neck yields flat/negative cents). Your fret may not look perfectly horizontal at its final resting position, that is, your bass and treble string may ring true at minutely different lengths of the scale. That’s ok! That is the beauty of movable frets — the player can find the truest intonation for their specific strings. When your fret rings true on the bass and treble note alike, your fret is now in its final resting position and you are ready to play.