Intonation issues

Hi, I just finished my first build, a fretted, 3 string tuned to open G. I built it on a 25.5 inch scale. I have checked and rechecked my fret measurements and when I play the first fret, I find that it is 1/2 step+/- too sharp (play position for G# but it plays an A, etc.). All subsequent notes are as well too high. If I use the slide over the fret, it is right on. What am I missing? Thanks in advance for suggestions.

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  • If all your notes are sharp, that indicates that each fret is closer to the nut than the scale length indicated by the actual distance from the nut to the bridge would allow. This could be either bridge placement or string height. Move your bridge slightly closer to the nut.

    Also looking at your bridge, it is straight across. Standard steel string guitar has 1/8" slant per inch of bridge, slanting closest to the nut on the highest pitched string and furthest from the nut on the lowest pitched string. Classical strings are straight across.

    On a 3 stringer with an inch and a half neck, the slant is probably a little less on the bridge.
  • Hi Squirrel,

    I had a few problems like this myself at first and it drove me mad. I've had a look at your pictures and the fret placement looks fine... (does it really have 29 frets? must have taken ages!)

    I think the problem might be the width of the nut, which looks very thick. If the string is contacting on the point closest to the tuners, this would effectively throw all of the frets sharp.

    What I do is make the point at which the string contacts the nut right at the edge, next to where the first fret starts (in theory this is where the nut should be), and slope the slot gently downwards towards the headstock (this way the contact point for the string is tiny, and will reduce buzzing).

    When I started making these I always thought the nut slots should be totally flat, but this is definitely not the case! Take a look at a factory made nut and you'll see they always slope downwards.

    Hope this helps!

    Rick

    • Squirrel got his nut right. LOL. I took off the nut, cut it in half, sloped it back, took some off the top and cut grooves to about a millimeter from the fret board. It is still a tad sharp but I can live with it. Yes, there are 28 frets. It did take a few minutes. I figured that with it being my first, I would learn by making all the beginner errors. Thank you for your assistance.
      • Hey Squirrel it's great you managed to get it sorted! As I said this drove me mad at first and I spent hours researching... if you wanted to iron out those last kinks try this:

        On string at a time, fret the 2nd fret and pluck. While you do this, bring your index finger down and fret the first so you have 2 frets depressed on the same string. If the note sharpens, your action may still be a little high at the nut. The thicker the string the stronger the effect is likely to be. (Essentially the string is having to bend in order to reach the fret).

        That said, it you can live with it, just enjoy it!

    • ...and to illustrate:

      306133955?profile=RESIZE_480x480I also tend to remove the strings and take a little material off the top of the nut when I'm happy with the action/intonation - when the strings are only just in/on the nut they seem to ring better. Could just be my imagination though!

      • i also agree after seing the picture  on  your   page   ,  that   nut  look  suspect  .

        also ,  .. it's hard to  tell  from  the  picture  ,  but  it  seems  the first fret space is a lil   wide too  .  could  just be the  photo  .  you  could test that  by     using a      bolt   as a  nut   set ontop  of the fret  board .(moveing  the nut line ahead  ) .

        • actually you can best test it just as i already said, with a capo on there...

          do that, and get the bridge in the right spot..

          then move onto your nut..

        • You, sir, have a suspect nut.

          I think as Squirrel has checked and rechecked the fret spacings they *should* be fine, especially as it plays in tune with a slide. Good idea on trying a moveable nut to compensate. I'm guessing this is a one-piece neck with no (separate) fretboard, so that should be do-able.

  • Misplaced frets will cause this problem, but there are a few other things you can check first, string height - with fretted guitars string height needs to be pretty low, around 3 mm, i usually experiment with the bridge height and get it as low as possible without the low string buzzing, also check the bridge is at a slight angle to the strings also check correct scale length at the centre of the bridge. (-:

  • sounds  like your strings are too   high  .  try lowering them  (lower  the  nut  and bridge  )so  they  bend  less when  depressed.

    the closer  you  get  to  the fretboard    , the better   intonation will match    between slide and  fingering. 

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