Rod True wrote:
Well, you're really only talking about a 0.012 difference which (in my limited experience) won't make much if any negative difference. There are many now who take much more than that off at the nut end (lazy nut compensation maybe), I know I do and it has actually helped with intonating the first few frets as string tension decreases as we move away from the nut. By moving the nut closer to the first fret, we effectively eliminated that extra string stretch and thus can tune in the intonation of the instrument more precisely. Mike Doolin wrote about this in his intonation articles found
on his website here and this will give you a much better understanding of cutting the fretboard back at the nut.
Also when setting up the intonation, I've started to capo at the 2nd fret and use the 16th fret harmonic to dial in the intonation, thus eliminating the nut all together. I've found I get better intonation along the fretboard and at the 1st and 2nd fret as well as the open strings this way.
Rod, I've been thinking some more about this, and I believe that the reason for the nut compensation is as I described it, and not what you've said here. I'm not interested in being "right" and you being "wrong", only in the pursuit of the most accurate and useful information. Perhaps we'll just agree to disagree.
I believe that your statements, "string tension decreases as we move away from the nut" and "By moving the nut closer to the first fret, we effectively eliminated that extra string stretch and thus can tune in the intonation of the instrument more precisely" are incorrect. If the nut slots are properly cut, there is very little deflection of a string when fretted at the first fret, just a tad more at the second, and more and more as you fret up the neck. So, the string is actually stretched - and therefore sharped - less when fretted at the first few frets, not more. This has to be the case, or else saddle compensation would not work. Let me explain that statement. For any given string, the saddle is a certain distance further toward the tail end of the guitar than the theoretical scale length. That's the "compensation". That distance can be understood as a certain percentage of the speaking length of the string for any given fretted note. The higher you move up the neck, the greater that percentage is, because the distance that the saddle is compensated is fixed, while, as you fret higher and higher up the neck, the speaking length of the string is getting shorter. Pitch difference is determined by the percentage that a string's length is changed (e.g. reduce a string's speaking length by roughly 50% and the pitch is raised an octave). Therefore, the higher you fret on the neck, the more each note is flatted by the saddle compensation, which is necessary to compensate for the greater deflection/stretching/sharping of the string.
If the nut is not compensated, there may be the perception that the notes played at the first few frets are sharped more, simply because that's where we'll notice the out-of-tuneness of the pitches relative to the open string pitches. But it isn't really that the fretted notes down there are being sharped more - the problem is that the uncompensated nut makes for too great of a pitch difference between the open string notes and the fretted notes.
Another issue to consider is the use of harmonics to set intonation. I don't recommend it. Harmonics don't actually give you perfect intervals, because strings have stiffness. Only a theoretical string with perfect flexibility would produce perfect harmonics. If you use a strobe tuner, you can often see this - you can have the open string tuned dead on, and a given harmonic will be sharp. When we set the intonation on a guitar, we're not really concerned with how the harmonics sound or how they compare to the fretted notes. We're concerned with whether the fretted notes are on pitch or not. So, IMO, it's better to just use open strings and fretted notes (checking with a strobe tuner) to set intonation. There's no real reason to limit that to notes played at the 12th fret (or 14th or whatever). You can check notes all over the neck. And, IMO, you'll get better results if you do not use a capo, because you really want to know how all the fretted notes sound when the open string is tuned exactly to pitch. If you can't get the fretted notes all up and down the neck to sound pretty darn close to in tune when the open string is tuned dead on (don't expect perfection for every fretted note) by adjusting the saddle, that tells you that your nut compensation should be adjusted a bit.