Adjusting truss rod

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Adjusting truss rod

Postby Ron Daves » Wed Apr 11, 2012 2:03 pm

The Low E string of my year-old guitar has a buzz at the 13th fret. The luthier at the place I purchased the guitar determined that the 14th fret is a little high.
He shimmed the saddle but this didn't really solve the problem and it made the instrument more difficult to play. I removed the shim and sighted the neck and it's higher on both ends than the middle. I tried tightening the truss rod in a clockwise direction and that seemed to take a bit of the bow out, but not all of it and the buzz is still there. What I am concerned about is how much tightening I can do on the truss rod before I damage something and, am I turning it in the right direction? Also, is this really going to solve the problem?

I've built two guitars and have dressed the frets as part of the process. I'm wondering if filing this 14th fret down a bit might solve the problem or just move it like it did on my #1 guitar. I'm concerned that if I mess around too much with this fret, I'm gong to have to replace it and face the possibility of chipping the fretboard.

Advice, please.
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Re: Adjusting truss rod

Postby Nick Middleton » Wed Apr 11, 2012 2:13 pm

It sounds like the 14th fret needs to come down. Do you you have a fret-rocker or some kind of straightedge that will only span 3-frets?
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Re: Adjusting truss rod

Postby Chuck Tweedy » Wed Apr 11, 2012 2:30 pm

Wait ... What?

Figure out at is wrong here first - as Nick said, figure out if the fret is high before messing with the truss rod.
And sighting down the neck is not the right way to adjust relief.
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Re: Adjusting truss rod

Postby Rodger Knox » Wed Apr 11, 2012 4:52 pm

+1 for figuring out what is wrong first. Then fix it.

Don't tighten the truss rod! First, tightening the rod will make the buzz worse and the rod should never be tightened without loosening the strings. If a rod adjustment is needed, it would need to be loosened.

Sounds like a fret may have backed out a little, or the top has dropped a little. That happens when it drys out, has the RH been low in your area?
(edit: I see you're in the desert, so has the RH been unusually low?)
A man hears what he wants to hear, and disreguards the rest. Paul Simon
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Re: Adjusting truss rod

Postby Barry Daniels » Thu Apr 12, 2012 9:43 am

When the 14th fret becomes the issue, often the cause is movement in the body/neck relationship instead of a lifting or too high fret. Humidity would be a good place to start looking for a cause.
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Re: Adjusting truss rod

Postby Ron Daves » Thu Apr 12, 2012 1:18 pm

Nick Middleton: You ask if I have a fret rocker. The luthier that worked on my guitar had one and showed me with that device that fret # 14 was high.
Barry Daniels: RH is always a problem here in the desert. That is why I keep a hygrometer in my case and use hydration sponges daily. I keep the RH inside the case at 40-55 %.
Roger Knox: See above.

As for "figuring out what is wrong", yep, that's why I'm here. The 14th fret is definitely a couple hundredths high. Had the same problem on m #1 and #2 guitars (had a buzz, just on different frets). On #1, filing the fret down just chased the buzz up a fret. Replaced the fret and dressed it and that solved the problem. On #2 I replaced the fret and superglued it in to solve the problem. I have a fret file and can file # 14 a bit then recrown.

Or, I could just leave it alone. I don't do much if any playing on fret #14.
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Re: Adjusting truss rod

Postby Rodger Knox » Thu Apr 12, 2012 1:43 pm

The fret rocker rocking on the 14th fret doesn't necessarily mean that the 14th is high, the 13th or 15th could be low and also need to be checked.
If the fret is high, the correct fix is getting it down where it should be, and you shouldn't have to chase the buzz up the fretboard.
If the fret is properly seated, then filing it down is the correct fix.
If it's not properly seated, then it needs to be pressed or hammered down, and some CA to keep it down wouldn't be a bad idea.
A man hears what he wants to hear, and disreguards the rest. Paul Simon
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Re: Adjusting truss rod

Postby Dave Gentner » Thu Apr 12, 2012 7:10 pm

You can't cure a buzz on the 14th fret by adjusting the truss rod. 14 is beyond the rod's range of motion. If you're certain the fret is properly seated then you need to level your frets. Remove the strings, adjust the truss rod so that a straight edge touches all the frets, mark all the frets with a black marker, then using a long block of hardwood and some 600 paper lightly sand the tops of all the frets. Sand along the length of the fretboard, not across it, so that your touching 5 or so frets at a time, the more the better. Be mindful of the radius. You'll immediately see what's high and what's low. When you see silver through the black everywhere you're done. Redress where necessary and polish. Put the strings on and adjust the truss rod so that your relief at the 7th is about 10 thousands or whatever is your preference. A half hour job and no more buzzes.
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Re: Adjusting truss rod

Postby Darrel Friesen » Thu Apr 12, 2012 8:33 pm

Rodger Knox wrote:+1 for figuring out what is wrong first. Then fix it.

Don't tighten the truss rod! First, tightening the rod will make the buzz worse and the rod should never be tightened without loosening the strings. If a rod adjustment is needed, it would need to be loosened.

Sounds like a fret may have backed out a little, or the top has dropped a little. That happens when it drys out, has the RH been low in your area?
(edit: I see you're in the desert, so has the RH been unusually low?)


Call me crazy Rodger, but an old luthier showed me how he adjusts the rod and it's how I've always successfully done it too. The guitar is laid flat on the bench, the lower bout is held down by a helper or clamped, firm but gentle pressure is put on the neck at the headstock and the truss rod nut tightened very easily as the pressure is off it. No more than 1/4 turn or so to start. It's usually more than enough.
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Re: Adjusting truss rod

Postby Michael Lewis » Fri Apr 13, 2012 12:50 am

With uneven frets and neck bow I think some basic set up procedure is called for. The frets and their relation to the fingerboard are the foundation of the playability, so that must be made right before any other adjustments are done. Hopefully the fingerboard was made planar before the frets were installed. This usually requires some adjustment to the truss rod with the strings and frets off. I usually give the truss rod a slight tension and flatten the fingerboard before the frets are installed, then the frets get slightly leveled to make sure they are all on the same plane. Sometimes the relief changes when the frets go in and this also needs to be attended to before going to the next step. Once all the frets are even the strings brought to tension and the relief adjusted. Electric guitars can often get by with VERY LITTLE (.002" - .005") relief but for more aggressive playing or acoustic guitars you need some more, between .004" and .015" depending on specific instrument, strings, and musician. I usually set relief for an acoustic around .010" as a starting point. Adjust the strings in the nut so they just clear the first fret when fretted between the 3rd and 4th frets, a little more clearance for the big E. Now you set the playing action by adjusting the saddle of the bridge. For an acoustic .070" for the little e and .090" for the big E measured between the underside of the string and top of the 12th fret is a very low action. For a more aggressive player .090" for the little e and .120" for the big E will allow lots of volume with minimal buzzing. It's all relative and must be adjusted for each case considering the physical limitations of the equipment and the preferences of the owner.

Tightening a single action (compression rod) truss rod flattens the neck, which brings the strings closer to the frets. A double acting rod can make the neck go either way by inducing forward or back bow. This in turn may require the saddle to be raised to avoid buzzing. Sometimes a tiny bit of adjustment can make a significant difference, it depends on the particular truss rod and neck. So, to summarize: 1) make the frets planar; 2) set the relief; 3) set string height at nut; 4) set action by adjusting the saddle.

If you do any of this out of sequence you are mostly wasting time and effort because each step is dependent on the previous step.
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Re: Adjusting truss rod

Postby Mark Swanson » Fri Apr 13, 2012 8:58 am

That lays it out really nicely, Thanks Michael.
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Re: Adjusting truss rod

Postby Rodger Knox » Fri Apr 13, 2012 12:58 pm

Darrel, the procedure you describe effectively loosens the strings, doesn't it?
I didn't say you had to use the tuners! :lol:
I actually use a couple of blocks and a clamp to flex the neck for rod adjustments. The idea is that the rod shouldn't be used to move the neck, just to hold it where it needs to be.
A man hears what he wants to hear, and disreguards the rest. Paul Simon
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Re: Adjusting truss rod

Postby Barry Daniels » Fri Apr 13, 2012 1:13 pm

Darrel, that technique sounds like it would put a lot of unneeded stress on the neck/body joint as well as the upper bout of the top. I also use a couple of blocks of wood but I glued them to a straight piece of wood that is supported by the blocks over the fretboard. A Quick-grip clamp places sufficient force to counteract string pressure allowing me to adjust the relaxened truss rod.
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Re: Adjusting truss rod

Postby Darrel Friesen » Fri Apr 13, 2012 7:09 pm

That's right Rodger, plus maybe a little more :) . You could be right Barry although in reality you are essentially just relieving string pressure and returning the neck to where it would be in its relaxed state. On second thoughts, I do also put a support under the neck near the heel. Anyway, it works for me. The key is gentle.
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