Acoustic Neck unresponsive to truss rod adjustment, is the neck toast?

Graham Monette · #1 08-25-2010, 05:33 PM

Hey guys, first off thanks for taking the time to read this and offer any help you guys can.

I bought a couple "project" guitars off of a guy that didn't want them anymore, one of them being an acoustic. I restrung it, and the strings are about a 3/16th off the fret board. I adjusted the truss rod and its not changing the action.

Is the neck bowed? or whats the best thing to do here?

Beej · #2 08-25-2010, 06:57 PM

Pics of the guitar from various angles will help.
I'd try a few things:
1. loosen the strings, back off the trussrod, clamp the neck into the position you want it to be in and then tighten the trussrod. Release it all and see how it does.
2. try lower gauge strings - they'll exert less force and cause less forward bow.

3. a risky method involves removing the strings, backing off the trussrod nut, and then clamping a progressively increasing backbow into the neck over a week or two. Then tighten the nut, restring and see where its at. CAUTION *do not do this with a guitar you really really care about* its a last resort to a really bowed neck and has only worked for me about 70% of the time.

4. an involved method entails removal of the fretboard, replacement of the trussrod and refitting of the fretboard. You could toast it and need to replace it which might not make it worth it.

My last recommendation is to google this especially referencing acoustics, there will be some good info out there...

vejesse · #3 08-26-2010, 08:33 AM

Is the neck bowed? Huh? How much relief is in the neck?

202dy · #4 08-26-2010, 09:23 AM

Data would help the diagnosis. String heights at the twelfth and last frets (top of fret to bottom of string, usually in sixty fourths of an inch) and relief (top of fret to bottom of straight edge, usually stated in thousandths of an inch) at the seventh fret are the basics. On an acoustic, saddle height (from the top of the bridge to the top of the saddle, in sixty fourths of an inch) is helpful, too.

Here are the basic tips:

Truss rod adjustment regulates relief.
Saddle adjustment regulates string height.

eaaa410 · #5 08-26-2010, 02:16 PM

You might check under the saddle for a shim. I bought a used acoustic bass that had high action that was causing intonation issues. I took the strings off with the intention of sanding down the saddle. The previous owner had installed a 1mm shim under the saddle. Once removed, the action went back to reasonable.

With acoustics, my experience has been that the truss rod won't change the action enough to use it for that purpose. Most acoustic basses tend to have higher action than electrics anyway.

Pilgrim · #6 08-26-2010, 02:46 PM

Check the saddle first. Many of them are too high, and can easily be replaced.

I pulled mine out, bought blank saddle material from Stew-Mac, used the original for a template (and did NOT modify it), made a lower saddle from the Stew-mac material and installed it. Works great and reduced the string height by more than half.

TGLbass · #7 08-26-2010, 08:47 PM

Mentioning the shim--that gets done allot! It seems like the first thing somebody does with basses and acoustics is slap a bad shim in the neck pocket or under the saddle etc! Not only can it cause a heel up problem in a bass neck--it's usually not needed if the person knew how to tweek a neck and the rest of the action to begin with. I had a tele bass (68) that had a fender medium pick in the pocket! The pic looks like it's from the 70's--it's yellowed quite a bit.

walterw · #8 08-26-2010, 10:02 PM

Quote:

Originally Posted by Graham Monette

Is the neck bowed?

that's what you need to tell us, not ask us

hold a string down at the first fret and the last fret, and look at the middle of the string (8th or 9th fret). how much of a gap is there between the bottom of the string and the top of the fret?

Graham Monette · #9 08-28-2010, 08:17 PM

^ Thank you VERY much guys. I'll check into all this when I get home.

I apologize Im a newb when it comes to setting up guitars and the like.

ehque · #10 08-30-2010, 05:06 AM

Quote:

Originally Posted by 202dy

Truss rod adjustment regulates relief.
Saddle adjustment regulates string height.

PLUS ONE.

Regardless of instrument, action adjustments are done with saddle height, not the truss rod.

Regarding acoustics, one way to reduce saddle height is to file down the underside of the saddle.

The other way depends if the top is bowing upwards. Is it? Humid storage conditions may cause an acoustic top to bow up, lifting the strings off the fretboard. Gently drying the guitar will cause the top to straighten out.