So what is intonation exactly? Intonation in regards to your guitar has to do with the notes being truly in tune up and down the fretboard. For example: the low E string should still read as close to E as possible when fretted at the 12th fret of the guitar neck. If the reading comes back as sharp or flat you can adjust your saddles to compensate for the difference. Having your intonation set correctly will play a major role in how good your guitar sounds. You definitely don’t want to be out of tune as you play higher and higher up the neck.
Setting intonation on the guitar is the final step in the setup of any guitar. The first thing you want to do when setting your intonation is to make sure you have a fresh set of strings on your guitar. Set the radius of the saddles on your guitar to match the radius of your fretboard. Tune the guitar to pitch and check the neck bow (we will cover this in another entry if you are unfamiliar with how to do this). After you have completed the steps above you will be ready to set the intonation on your guitar.
Most electric guitars nowadays have individual saddles you can adjust forward and backwards. This is a fairly easy process if you understand what you’re doing. I have heard a lot of people say that the way they check their intonation is to play the note open and then hit the harmonic at the 12th fret. This isn’t totally accurate. You still need to fret the guitar at the 12th fret to hear how far off the note is. The harmonic is just a way to gauge whether or not the intonation is off bad. When you press the string down to the fret you are bending the string slightly. This bending makes the note sharp. So the further you go up the neck the sharper it will become because the string gets further and further off of the fret board as you get closer to the bridge.
Get a good tuner and get every string as perfectly in tune as you can. Do this a couple of times because if your guitar is way off the neck will move (bow slightly forward) and by the time you get to the higher strings the lower strings have dropped pitch. You may need to stretch your strings a couple of times and retune. Getting the guitar perfectly in tune is critical.
Now go one string at a time and check the tune at the 12th fret. Start with the low E open and then check it at the 12th fret. Literally fret the guitar at the 12th fret, no harmonics here. If the tuner says it’s still in tune move on to the A. If it is sharp you need to lengthen your string. To do this tighten the saddle which will pull it back thus lengthening the string. If your reading comes back flat you will need to shorten the string. To do this loosen that saddle. This will shorten the string because the saddle will move forward. You don’t want to turn the screw in the saddle much at all. Small adjustments go a long way. I would adjust about a quarter of a turn per reading.
After you have turned the screw whichever way it needs to turn, go check your tuning again. The open string will now be out of tune so tune it first. Then you will need to fret the guitar again at the 12th fret of the string you’re working on and check the tuning there. If it is still off go back to the previous step and adjust a little more. This is a bit of trial and error but you will get better at judging how much to adjust every time you do it.
You will begin to notice that the saddles will form a certain pattern pretty much every time you set the intonation correctly. Once you have done this several times you will be able to get the saddles pretty close to the position that they need to be before you ever do anything in regards to setting the intonation. Good luck and if you have issues come see me.