Hi everybody,
I'm not handy or crafty at all, and I know even less about guitars. So naturally I decided to build a cbg for my daughter. Mistakes were made and corrected and now I have a lovely guitar. The specs: 3 strings, 30 inch scale, the neck is inside the box, no tailpiece. The strings (E, A and D) are attached to the outside of the box by a hinge.
The question: it doesn't stay in tune for more than a few minutes. There are a few factors that might encourage loss of intonation. The lid is tight, but not actually secured. The neck is also tight, but not nailed or glued to anything. Is this why it won't stay in tune? If that's the case, there are some supports inside the box for the neck - is it okay to screw the neck into those supports and will that fix my intonation problem?
For what it's worth, I really enjoyed this project and I'm very happy with the outcome. I'll definitely be building another one.
Replies
for starters, there is the thing called "New String Blues" - that special style of music where the tuning drops as you play a new set of strings that aren't stretched out yet and haven't fully equalized the tension in the wraps around the tuners, but that goes away after about 10 min of playing-retuning-playing-retuning-etc.
Next is neck bowing, if the neck wood is not strong enough, it slowly bends under tension and goes from Alan-A-Dale's instrument to Robin Hood's archery bow. Use a straight edge and see if yours is increasing.
Then there is nut & bridge creep. Threaded rods can/will roll as you tune up a string, moving out of position, and then as its played the break angle pushes them. A threaded rod nut needs to be captured by a groove to stop it from walking to the head as you tune up and from walking away from the head as its played. Threaded rod saddles constantly walk away from the tail and need to be trapped in a groove in a bridge base.
Also there is string cutting into the tail - strings run through holes in wood without ferrules will cut into the wood and go flat, it can also happen with metal tail pieces that use soft metal, or the tailpiece deforms under tension, the barrel wraps around the hinge pin stretch, the holes deform, etc.
I assume the hinge tail-piece is screwed through the box into the neck inside the box, otherwise I would have expected a catastrophic failure on the neck/box union the first time it got tuned up?
Most likely, the neck being unsecured is the chief culprit, with probably the scale length varying minutely as it's played, only a small movement will make maintaining tune difficult, and being 30'' scale , the extra tension will magnify the problem, and i'd suspect a bit of neck bowing as well adding to the issue. Without a neck tension rod 30'' is pushing the neck's ability to remain straight. You don't say if the guitar is fretted or not, if not, i'd recommend shortening your scale to around the 24-25'' range and securing the neck
I figured as much. I didn't think about the length of the scale but that makes sense too. I can definitely shorten the neck but I'd lose some esthetic value. I'll have to think about that. So screwing the neck into place is the way to go, is what I'm hearing.
Oh, I did fret the neck but then removed them. It just didn't play right and I didn't feel like solving a fret problem.
I also have another minor problem. The A string has an interesting vibrating sound. It's not unpleasant but maybe doesn't belong there. Hard to describe as I don't have the terminology but it's not a pure tone. As far as I can tell, the string isn't touching anything (it's a pretty high action which is why I removed the frets). I've used a threaded bolt for the nut and a piece of grooved wood for the bridge.
Thanks for the feedback and more is welcome!