On two guitars I recently built they are a little bit out of tune at the 12th fret. When I tune the bottom string to open G and then play it at the 12th fret it comes out sharp. I’m hoping that’s something that I can adjust to make it right.I tried to be real careful when I measured the scale length and Frets and set everything up. So I’m not sure what the deal is but if you have any thoughts on what it might be or how to fix it I’d love to hear.
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Hi Jon, this must be one of the most popular queries.
As BR suggests moving the bridge back from your initial scale length position [compensation] allows for the different string thickness and height.
Just for you to file away, here are some recommended distances back from the true scale length,[compensation], subject to string gauge and height at the 12 fret:
1st 1.49mm
2nd 2.80mm
3rd 1.03mm
4th 1.85mm
5th 3.11mm
6th 4.79
Pictured here are a couple of ways I use to get my guitars intonated. One moves the whole bridge back, the other plots the position where I would compensate each string by filing the saddle.
Thank you, Taffy. You just confirmed my skill set as 'hack'.
Hey James, sorry about that, but that's a bit harsh mate.
I remember being a 'hack' possibly 60 years ago, and I can remember the first instruments I had possibly wrecked, or at least devalued through inexperience. But that does not last forever if one is willing to take chances, seek information, listen and learn.
I have the first notes of the first instruments I worked on, and I say to myself "did I do that"?
Taff
I really am flying by the seat of my pants most of the time. A lack of tools also comes into play. I really want a jointer and a thickness planer. Just a week ago I told a volunteer on the ship about cbg's, and yesterday he shows up with pix of his first build. Still in progress, but he's even making the box. Out of Walnut. With mortise/tenon corners. I'm so far away from that...
Listen to Taffy and Rat before you listen to me (being a noob), but I ran across that on my last build too. I ended up slanting the bridge/bolt, mine had to go about 45*, with the low string being longest, but damn if I didn't nail it on all 3, at least close enough for gov't work...
Like Keith said. If you have a movable bridge try this.
If it's sharp you need to move it forward and make the string shorter
If it's flat do move it back to make the string longer.
Every time you move the bridge retune your string and try again.
You can do this to adjust the intonation of both your first and third string. The middle string is at their mercy. You can check out vids on how to adjust the intonation on a straight bridged acoustic guitar. That's a whole new monster to do.
Hi BR, I think you may have a typo there??
Taff
Yep. I get em backwards.
If it's sharp you have to move the bridge back and make the strings longer
if it's flat you have to move the bridge forward to make the strings shorter.
No wonder it takes me forever to intonate my guitars....: )
If your bridge isn't glued down move it until it comes into tune. Usually the bridge is angled just a bit, towards the bottom of the guitar.