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Thread: Intonation problem

  1. #1

    Unhappy Intonation problem

    Hey I'm very new to electric guitars, so please have patience with me.
    I've build a guitar from the cheapest strat kit on ebay and with new pickups and bridge it actually feels pretty good.
    But sadly I have big intonation problems and there are so many possible reasons.
    I set up the intonation so that the 12 fret is in tune. But now all the notes on the lower frets are sharp and even on the higher frets I get sharp notes when I press a little bit to hard (bar chords especially).
    The solutions I thought of are:
    - sanding deeper groves at the nut (I'm scared of overdoing it and the strings buzzing)
    - shimming the neck (maybe the neck is just a bit to tilted)
    - truss rod adjustment (but my truss rod feels like it's already on its limit. Maybe I just got a bad one (the kit was only 50 bucks))
    - sanding the frets (should the string touch the fret board when fretted or not?? Maybe they are just to high)
    - Any other things I might have forgotten???

    I would send you pictures, but I don't know of what exactly. Let me know where and I will take pictures

    Thanks for helping me find and fix my problems

  2. #2
    GAStronomist FrankenWashie's Avatar
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    Hi Lennard,

    the intonation should be adjustable at the bridge, there will be adjuster screws that should allow you to adjust the bridge saddles. Forward or backward to balance out the sharpness or flatness of your intonation on each string.

    The nut groove depth and nut height should only influence your string action and potential buzz.

    Your truss rod will only straighten or bow your neck, which won’t give you a great deal of assistance with your intonation.

    Shimming the neck should only be done if you have a serious action or fretboard height/angle issue.

    what kind of bridge is on it, Tremolo or Hard tail?
    FrankenLab
    Where “What if?” meets “Why the hell not?!”.


  3. #3
    GAStronomist Simon Barden's Avatar
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    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.

  4. #4
    Thanks for the advise Of course I tuned the open string and the 12th fret
    Quote Originally Posted by Simon Barden View Post
    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??

  5. #5
    Quote Originally Posted by LennardPlay View Post
    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!

  6. #6
    I have a tremolo

    How much action is to much action? I have the feeling it's pretty high on the upper frets

  7. #7
    GAStronomist Simon Barden's Avatar
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    Quote Originally Posted by LennardPlay View Post
    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.

    Quote Originally Posted by LennardPlay View Post
    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.

    Quote Originally Posted by LennardPlay View Post
    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.

  8. #8
    GAStronomist Simon Barden's Avatar
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    This is how I set up my guitars for a low action:

    Set up the truss rod so that the neck has a very gentle curve in it - not much relief at all. Turning the trussrod nut clockwise (viewed from the hex key end) will straighten the neck, turning the trussrod nut anticlockwise will allow more concave bow in the neck.

    As your nut height is high, I'd then recommend putting a capo on the first fret (or taping the strings down hard), so the effect of the nut is taken out of the equation. If you've got a chromatic tuner, then tune the strings a semitone higher than for open strings so the tension is correct.

    Then look at the action from the 12th fret and above. I then adjust the saddle height so I can just fret and bend all the strings cleanly. I normally start with the saddles low and work up the action height until I can bend the lower strings without choking, and the upper (wound) strings which I don't bend far enough to be an issue, sounding cleanly.

    Then look at the action at the lower frets. Using the capo has taken the nut slot height out of the equation so you get a good idea of what's really happening. Do all the notes sound freely without buzzing? The action at the 6th/7th frets may still feel feel quite high. If so, tighten the truss rod slightly, maybe 1/16 to 1/8 of a turn. The neck will be flatter and the 6th/7th fret action will be lower (also at the upper frets but it's the lower frets we're interested in at the moment). Do those low notes fret and bend cleanly? If so, you could try another very small tightening of the truss rod. Repeat until you start to get buzzing or choking on the low frets and then back off the truss rod slightly until this stops.

    Go back to the high frets and test them for choking and buzz. Straightening the neck will have pulled the strings nearer the frets, so you'll probably have to raise the saddles slightly by a small amount. Once those upper frets play OK, then that's the time to take the capo off and file the fret slots. If you file them when the action is high and then lower it, you'll probably end up with 1st fret string buzz, so it's important to only do it once the rest of the action is sorted.

  9. #9
    That's a genius way to set up a guitar
    I always felt like there are so many variables, but the way you do it sound really straight forward.
    Thank you really much ^^

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