Truss rod when planing fretboard and dressing frets.

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Truss rod when planing fretboard and dressing frets.

Postby Brian Evans » Sun Jul 15, 2018 8:40 am

I was shocked and dismayed at a problem I found yesterday with my latest guitar, and I am sitting pondering how to fix it. Problem is I put heavier gauge strings on (.013 - ,056, for a trial) and instantly the instrument developed a giant buzz all over the fretboard. The tension of the strings pulled the neck into a position where the truss rod (normal double-acting type) was completely neutral, and with no load it buzzed like crazy. Relief was dead on where I like it (tiny amount, almost flat). If I take the relief out completely, or add some, the problem gets better but I can't really put load on the truss rod sufficient to dampen it with these strings, so I will change them and go back to my normal (.011 - .050) and see what happens.

What I think happened is this: I planed the fret-board with the truss rod in a neutral position, getting the un-fretted neck dead straight. I installed the frets, and induced a back bow. When I dressed the frets I adjusted the truss rod to straighten the neck, which I think left the back bow intact. Now, with the heavy gauge strings the tension takes out the back-bow and releases the tension on the truss rod. With the light gauge strings the truss rod is still acting to counter-act the back-bow.

So I think the mistake was in the fretting/dressing stage, using the truss rod to counter-act a back bow. What should I have done? What should I do now? I can think of a couple of ideas. One is put the light gauge strings on and wait for the problem to re-occur in a few years when the tension makes the neck take a different set. Two is re-dress the fretboard with the truss rod neutral. Three is take out the 7th fret marker dot, drill down to the truss rod and somehow inject epoxy to glue the middle of the truss rod to the neck.

What do you all think? TIA, Brian
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Re: Truss rod when planing fretboard and dressing frets.

Postby Bob Gramann » Sun Jul 15, 2018 9:01 am

I usually install my double-acting rods with a couple of spots of silicone caulk in the bottom of the channel and a couple of spots between the flat and the round parts of the rod. Once, when I forgot to do that, I had the problem you describe on a banjo. Fortunately, I could remove the 5th string tuner, drill into the cavity, and inject some caulk there. Personally, I wouldn’t use epoxy to fix the problem. It will cure hard and won’t damp all of the pieces. I would try to figure a way to drill at an angle (either by using one of the double dots at the 12th fret or by removing a fret) into the cavity between the round and the flat parts of the rod and inject silicone caulk there. If you don’t fix it, there will be a point sometime in the life of this instrument where things will be just right for it to buzz again.
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Re: Truss rod when planing fretboard and dressing frets.

Postby Peter Wilcox » Sun Jul 15, 2018 10:27 am

I had this problem with a guitar after switching string gauges (from 0.010's to 0.009's.) Buzzing high E string, and a neck rattle when I banged on the back of the neck. It was a double action rod, and no adjustment would resolve it. I finally decided on Frank Ford's method using an injection of diluted rubber cement (several ml's probably using a syringe and needle) into the truss rod cavity from the adjusting nut end, and the buzz disappeared, as did the rattle.

http://www.frets.com/FretsPages/Luthier ... ssrod.html
Maybe I can't fix it, but I can fix it so no one can fix it
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Re: Truss rod when planing fretboard and dressing frets.

Postby Brian Evans » Sun Jul 15, 2018 10:56 am

Thanks, guys, I should have known Frank had a fix for this! Right now I have the guitar playing beautifully with the fretboard dead flat, but as Bob says, it's gonna come back, you just know it is. In future I will be more aggressive with the caulk, I didn't use any on the thick flat upper rod, just the round lower rod.

Is there a strategy to adjust the truss rod when planing and fret dressing to avoid the slack truss rod effect altogether?
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Re: Truss rod when planing fretboard and dressing frets.

Postby Christ Kacoyannakis » Sun Jul 15, 2018 5:05 pm

As well as using silicone caulk, as Bob does, I always install the two way truss rod a bit below the top face of the neck, and glue a spline to the top. I use any scrap of wood lying around, but it is usually mahogany. When you glue it in, you put a spring clamp at each end and one in the middle, which puts a little bow into the top of the rod. Plus, the spline is glued to the top of the bar, and the sides of the channel. I know they say you can put the flat of the rod flush with the neck, but I like to have a full wood surface to glue my fretboard to. Plus, one time I needed to level the top of my neck before gluing the fretboard on, and it was impossible with the metal rod flush with the top of the neck. You learn from these mistakes (if only I can remember not to make them again!).
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Re: Truss rod when planing fretboard and dressing frets.

Postby David King » Sun Jul 22, 2018 11:54 am

Did you glue the frets in? If not you can usually pull the neck forward and force the fret barbs deeper into the sides of the slots and get back to your neutral flat fingerboard.
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