Nokiab GuitarsAll About Acoustic Guitars

Need help with my diy guitar project!?

I’m working on a Harmony H-802 (probably from the 70’s or so, but that’s beside the point). When I bought it, the action was disgusting, i.e. multiple centimeters off the neck. I’ve adjusted the truss rod over the course of a few weeks to try and fix this. I’m pretty sure that it has reached the most I can adjust it, as now it makes a scar popping sound when I try to adjust it. I think part of the problem might be in the bridge, which is essentially a curved piece of metal. Would changing to a tune-o-matic bride help with this? Does anybody have suggestions on how I could further fix the action? It’s still unplayable as is.

The criteria for adjusting the truss rod isn’t how far it’ll go…it’s getting the proper neck relief. Ideally the fretboard should be straight or have a teeny forward bow. You can check this with a straightedge, or simply by fretting a string on the first and highest fret simultaneously. At the midpoint, there should be a gap between the string and the frets of about the thickness of your high E string. The popping sound you hear when tightening the truss rod may just be rust on the threads…try a drop of machine oil. Don’t force anything, it’s possible to snap the truss rod…don’t ask me how I know. If you can’t get enough adjustment out of the truss rod, try byrde94’s idea of using a spacer.

Only after the neck has the proper relief should you start adjusting the bridge. From the pictures I’ve seen on the web, your bridge has a height adjustment on either end…just like a tune-o-matic. Lower the bridge until the strings are as low as possible without fret buzz. If the bridge won’t go low enough, you may need to shim the neck. You have to un-string it and remove the neck, then place a very thin wooden shim under the rearmost part of the routed out area under the neck. The shim may not need to be much thicker than a couple of credit cards. You probably only need to gain a fraction of a degree of backward tilt.
The only advantage that a tune-o-matic bridge has is that it has individual string adjustments for intonation. Assuming that the guitar was once playable with the existing hardware, I wouldn’t bother trying to swap bridges.

The last piece of the action adjustment is to check the top nut. Think of it as a ‘zero fret’ and make sure the strings pass over it at the same height as any other fret.

It’s certainly possible to start replacing parts…new bridge, new neck, etc……but then you’ll have a frankenguitar. With a little care and attention to detail, I’ll bet you can bring this relic back from the dead without any new body parts. That’s part of the fun, right? Good luck with your project.

Gospel Harmony Boys – Over in the Gloryland