I thought to make a 4 string, fretted CBG for my first build. I thought if I could build this one then any 3 string I did subsequently would be a cinch. Well, I think I bit off more than I could chew.
The build turned out pretty good for a first time ever making anything like this, but the frets are off, sort of. The harmonics are dead on... beautiful, but using a fancy vibration tuner, and a stompbox as well, when fretted the strings don't ring true. The notes fretted are wrong and it is hard to tune by ear. Don't get me wrong, it actually sounds close and plays okay when chording and strumming. But the intonation is wrecked.
The top string is currently tuned to "A". So open I get an "A". Fretting the first fret I get an "A" at +150. 2nd fret plays "B" at -150. 3rd fret is "B" at +150, etc... etc... HELP!
I am using a 5/8" bolt for the nut and bridge (only the bridge has a thin piece of wood below it). I swapped out for a smaller nut bolt (the next size down) and took out the piece of wood under my bridge. I even swapped out my tail piece for one with 4 holes. I also added string trees/keepers to the headstock. These all helped the sound of the thing, reducing some slight fret and string buzz, but that's about it.
Is the distance from nut to the 12th fret the same as the distance from the 12th fret to the top of the bolt bridge? Your pic is at an angle, but it looks like your bridge placement is a few inches backward too far.
Secondly, once you get the 12th fret exactly in the middle of the bridge and nut, confirm that the total distance from nut to bridge is the same as the scale length you used to determine your fret spacing.
I'd make a guess that you need your bridge to be near the bottom of the loop in the T of the box logo or maybe even close to the vertical part of the T. That's just eyeballing it off a skewed pic, but I think it's a good guess.
The placement in the pic is off (sorry, but the only quick pic I had). Yes, the measurements all add up. And you are right (good eye), that's about where the bridge does actually go.
With my harmonics right on the money (5th, 7th, and 12th fret) this has me really puzzled. I would assume if my bridge were off then the harmonics would be too.
How high is the action at the first and 12th frets?
How is the string tension? Really tight or really floppy? Try tuning all strings down a whole step then redo the tuning check. If the strings seem too floppy then tune up a half step and recheck.
Just had a look at the pic, even allowing for the perspective, I reckon the bridge should actually be around where the pickup is, or even in front of it, so the whole thing looks wildly out. To get "in the ball park" the distance from nut to 12th fret should be the same as 12th fret to bridge.
Cool build. Looks killer. Just make sure the nut is low enough. Not too low that it's buzzing, but pretty damn close to the 1st fret. The bridge should be a few milimeters back from the theoretical position. This youtube video helped me out a lot with setting the bridge at the right place : https://www.youtube.com/watch?v=o3GPARmX0C0. Oh, and since you are using bolts, make sure you are taking your mesurements from the center of the bolt.
Thanks for all your help and suggestions. I think I really screwed up now. I have a Luthier friend tell me it was something with the nut and/or the tailpiece. So, I swapped out the original tail piece for a smaller hinge and I added the two middle holes. Now harmonics only ring true without the bolt, making the new tailpiece also the bridge.
The 12th fret is close to 13 inches from the nut. That puts the theoretic sweet spot for the bridge (and about where I attached my piezo buzzer to the neck inside the box) around where the cursive loop is in the "T".
The measurements for the strings above the fretboard are 3/16" at the 1st fret and 3/8" at the 12th fret.
It's strange I tried chording it and playing with the tuner on. An "A" chord is only slightly sharp. A "G" rings true. What strings I can chord for a "D" ring slightly flat, but "D" noethe less. An "F" chord rings as an "E" +150 (like an "E" Sharp, but not quite an "F") and a "C" shows up as a B +150 (like a "B" Sharp, but not quite a "C").
I used WFret if memory serves... I have battling this issue for months and even posted in other forums to no avail. I think I remember measuring from fret to fret, and not from the nut each time. The measurements weren't cumulative from the nut, if I remember correctly, but distances from fret to fret. Sadly it sounds like I need to scrap the neck and start over on this one. :-(
I only said "almost 13"" cause it's around there, but by the time I got to my computer I had forgotten the exact measurement. I was fairly precise with the measurements, but I see what you mean. Oh well, thanks for the advice. Now I know for the next build (which will be fretless to say the least)...