Intonation problem

[Simon Barden]

You need to set the open string to be in tune, then you check the 12th fret for being in tune. If not, adjust it, then tune the open string again then check the 12th fret. If not in tune yet adjust. Then tune the open string again then check the 12th fret. If not in tune - adjust again. Repeat until intonated.

But a high nut will help make the lower frets sound sharp (FW is wrong here), so you need to get the nut slot depth right before you intonate.

This should either be done with nut files (don't use just sandpaper or you'll end up with wide slots that make the strings buzz), or by sanding the bottom of the nut until the slots are low enough.

You'll need to remove the nut, so if it's not already loose, tap it gently from the ends until it comes lose. Don't tap it forwards or backwards as you're likely to snap off the end of the fretboard by the headstock. Clean the slot and the nut, then sand away a bit at a time. Always rub the bottom of the nut on sandpaper that's resting on a flat surface. Don't sand by hand alone, otherwise you'll give it a curve. Keep the edges of the nut at 90° to the surface. You can keep the strings on when doing the sanding, just loosen them each time you remove the nut then retighten when the nut is back in place . String tension will keep the nut in place for testing.

When done, glue the nut back in with some PVA or Titebond.

If you've got any feeler gauges, hold the strings down at the 1st fret with a capo or tape. The string height at the 2nd fret is what you're aiming for with no capo for the string height above the 1st fret (but no less). Sand a little and often once you get close.

You can always make strings go slightly out of tune if you press really hard, especially if the frets are tall, so just play normally.

[LennardPlay]

Thanks for the advise Of course I tuned the open string and the 12th fret

But a high nut will help make the lower frets sound sharp (FW is wrong here), so you need to get the nut slot depth right before you intonate.

Can you explain what FW stands for?
My father has tiny triangular files. I think they should work
You say that the distance between 1st fret and (open) string should be the same as the second fret when holding down the first fret. Right??

[J.R.303]

Thanks for the advise Of course I tuned the open string and the 12th fret

Can you explain what FW stands for?
My father has tiny triangular files. I think they should work
You say that the distance between 1st fret and (open) string should be the same as the second fret when holding down the first fret. Right??

FW = FrankenWashie.
The other guy posting in the thread!

[Simon Barden]

Of course I tuned the open string and the 12th fret

OK. just wanted to check. In taht case, either the frets haven't been installed in the correct position or (more likely) the strings are very high.

My father has tiny triangular files. I think they should work

Not recommended. A very 'tight' V shape can work (say less than 10°), but with a full equilateral triangle shape with a 60° angle, the sides of the slot don't keep the string in place very well, which can cause problems when playing.

You say that the distance between 1st fret and (open) string should be the same as the second fret when holding down the first fret. Right??

Yes, or just slightly greater.

Lets take an extreme example to understand what's happening:

With the strings 20mm off the fretboard at each end, you have to increase the string length significantly to be able to press it down against the fret. To do that, you have to stretch the string by roughly 1.2mm if you fret at the 12th fret, and to do that, you have to put the string under a lot more tension. If you increase the tension of a string, its pitch goes up.

If you then fret that string at the first fret, then you have to increase the string length by 5.5mm, which means you put the string under a lot more tension to do so, so the string goes even sharper.

Now bring the string height down to a more sensible 2mm at both ends. At the 12th fret, you only have to stretch the string by 0.012mm, and at the 1st fret, by 0.059mm. That's not a huge amount, but it still means that at the 1st fret, the note is still going to sound sharper than at the 12th fret.

By intonating and moving the saddle back to increase the overall string length, the position of the 12th fret is effectively moved in relation to the string length, so that the distance from the 12th fret to the saddle is now just longer than half the scale length, which lowers the fretted note pitch, and which offsets the extra tension created by fretting it, so the open string and 12th fret note are both in tune.

But this isn't enough to get the first fret in tune, as it still requires more tension to fret than the 12th fret does. And which is why you are noticing the lower frets play sharp although you've intonated at the 12th.

The only way to help this is to lower the height of the strings at the 1st fret in relation to the height of the strings at the 12th fret. We do this by adjusting the nut slot depth to be as low as possible without the strings buzzing on the first fret.

Bring the height of the string at the first fret down to 0.3mm, and you actually then need to stretch the string less to fret it there than you do with 2.0mm at the 12th fret (0.0013mm vs 0.012mm).

Now a lot of this is compensated for by the position of the frets being adjusted for this effect, but any guitar tuning and fret position is always a compromise. It can never be in perfect tune, as such a thing doesn't exist. But you can certainly get it good enough for rock 'n' roll.

So you should now see the value of a good set-up, with a medium to low overall action and the nut set so that the strings are close to the first fret, and not a long way above it.