unforgivable neck adjustmnet!

[bobbyg67]

i know from many previous posts that the truss rod is not to be used for string height adjustment. my question is, if the truss rod adds relief or (increases bow in neck) or decreases relief (makes the neck straighter), why wouldn't taking some bow out of the neck, thus making it straighter and bringing the strings closer to the neck, be an acceptable solution for minor lower action. wouldn't it be better to do this first as opposed to shaving the saddle and possibly going to low, and then needing a shim and on and on? if the truss rod adjustment brings the strings too close to the neck, its an easy fix to reverse and just put it back to the previous setting. i'm not talking about a big change, just a minor noticeable difference. is this the unforgivable sin as i've read previously?

[Brent Hutto]

The truss rod affects the action at the middle of the neck (something like frets 5, 6, 7, 8, 9, 10) relative to the ends of the neck. The object is to get the action approximately the same all up and down the neck except adding just a tiny bit extra in the middle where the strings move more.

Trying to use the truss rod to raise or lower your guitar's action would be like trying to use the choke instead of the throttle to control how fast your car is going (if you're old enough to remember chokes). Yes, if you choke the engine the car will slow down but it also won't run right. Better to just let off the throttle a bit.

If you want to see higher or lower action at, say, the second fret or the twelfth fret you're going to end up with a bowed or back-bowed neck way before you change the action more than 1/64" or so. And then you'll end up cranking some more until you damage the neck and you still won't have affected the action near the nut and near the body enough to matter.

OTOH, if you want different action around the sixth or seventh fret and want it to stay the same at the first four and last ten frets...then you don't want an action change at all. You're adjust the relief which is what the truss rod is in there for.

[ljguitar]

Originally Posted by bobbyg67

i know from many previous posts that the truss rod is not to be used for string height adjustment. my question is, if the truss rod adds relief or (increases bow in neck) or decreases relief (makes the neck straighter), why wouldn't taking some bow out of the neck, thus making it straighter and bringing the strings closer to the neck, be an acceptable solution for minor lower action. wouldn't it be better to do this first as opposed to shaving the saddle and possibly going to low, and then needing a shim and on and on? if the truss rod adjustment brings the strings too close to the neck, its an easy fix to reverse and just put it back to the previous setting. i'm not talking about a big change, just a minor noticeable difference. is this the unforgivable sin as i've read previously?

Hi Bobby...
You make a good point, and from my perspective, no it's not the unforgivable sin.

Often just the act of putting the proper amount of relief in the neck has the bi-product of lowering the action. This simple act of setting the relief to the proper height can also cause buzzing if the saddle is short.

I think many people (more than will perhaps admit it publicly) tweak their action up/down a tad using the truss rod - especially once the neck is setup properly and the action is adjusted to where they want it.

I've seen a good number of acoustic artists who tour through our area with the truss rod plate off their Taylors which suggests they are tweaking the action to eliminate buzzing.

The key though, is to have the action adjusted properly to begin with. This involves the string height at both ends of the neck as well as the relief. If it isn't set properly at both ends (nut and saddle), either buzzing or unplayably high action can result.

[Brent Hutto]

I agree with Larry that once the action is in the right (playable) ballpark a lot of people nudge it back and forth with the truss rod. That's how the guy I used to take lessons from does it, probably from years of gigging and not being able to always tweak a nut or saddle on short notice.

But if the action's off far enough that you're even considering changing the saddle then you're outside of the plus or minus a tiny fraction you get as a side effect of changing the relief.

[ewalling]

I bought a L'Arrivee PO9 from Guitar Adoptions around a year and a half ago. The action was set really low and I was getting fret buzz on frets 1-5, particularly with the third string, I seem to remember. I took it into a local tech and he tweaked the truss rod. I have to say that the buzz disappeared and there is no noticeable bow in the neck now.

[evhwolfgang]

All of the things we are discussing here must work in concert (no pun intended) to achieve playability and intonation. Before setting your action, make sure that the neck relief is correct, since indeed if your neck has too much relief and you lower the action, you can wind up with the guitar fretting out in the end positions (usually within the first 3 frets and above 12) once the relief is set correctly. Guitar necks (especially 12 strings) are under tremendous tension and that tension must be balanced. In order for the guitar to play in tune, the intonation must be correct up and down the neck. So, neck relief affects action and intonation, action (by changing the tension as you raise or lower the action) can affect neck relief and intonation. I do not do much setup of acoustics, but I do a ton of setups on my own electric guitars and on friend's guitars. Electric guitar bridges are designed for these actions to be undertaken by the players. But, acoustics are quite a bit tricker and you can wind up shaving and shimming a lot of bridges if you don't know what you are doing. My advice is to take your guitar to a good luthier who specializes in acoustics and have them do it. You'll spend less money and have a whole lot less aggravation in the long run.

Good luck...

[Howard Klepper]

Bobby, you are right that a truss rod adjustment may lower the action, and also right that the neck relief should be set correctly before action is adjusted at the saddle. The warnings you hear are well founded, though. A lot of people have the mistaken impression that the rod is there to adjust action height, and if someone does not know what they are doing with it, they often will do more harm than good. Once relief is properly set, the truss rod adjustment should stay put. Tweaking action with the rod will almost invariably cause some part of the neck to play less well or buzz. If this works for your teacher, it may be because he doesn't use all parts of the neck, or because his playing skill is sufficient to compensate, and does not require an optimal playability over all parts of the neck.

[devellis]

This seems to come up a lot. What puzzles me is why people would assume that an action problem is a relief problem rather than a saddle height issue. If (a) the instrument was not set up correctly or (b) the neck bow has changed (as when different string gauges are used) or (c) the playing style requires a different amount of relief than the setup assumed (as when switching from gentle fingerpicking to aggressive flatpicking) or (d) there are issues isolated to specific frets that indicate a relief problem (which almost certainly would be the result of some combination of the preceding), then a truss rod adjustment is in order. If the action is too low or too high in the absence of these issues, the bridge or nut seem like the likely candidates for attention. Having said that, I've been guilty of tweaking the truss rod in an attempt to modify the action a bit without resorting to altering the saddle or nut. For the most part, it hasn't worked out too well. I suspect when it has worked, it was because the previous setup wasn't optimal. Of course, YMMV.

[ljguitar]

Originally Posted by devellis

This seems to come up a lot. What puzzles me is why people would assume that an action problem is a relief problem rather than a saddle height issue.

Hi Bob...
Because of a lack of good instruction, a misunderstanding of how the action on a guitar works, and as musicians who are used to being broke (having limited funds) we are looking for quick fixes.

But, the question in the original post is asking if it will hurt to raise and lower the strings using the truss rod, and it will not damage it.

Also, seasonal changes require action changes in environments where we have dry and wet seasons, so we pay to have a guitar setup properly and 6 months later it is either too high or low - and of course the optimum answer would be to just own a low and high saddle. Classical players do.

But most of us were not informed enough to be that forward thinking when we had the guitar in for a setup. And the reality is, if the guitar was setup properly with adjustments at both nut and saddle and the relief properly set, then a tweak will probably suffice, not injure the guitar, and not change the playability (may improve it if the action has gotten too high as a result of seasonal change).

[RustyAxe]

Good thread. It seems that electric guitarists seem to always look to the neck for adjustments. Acoustics are just different.

Does anyone have an online resource that shows the difference between a properly set up neck relief vs improper? I've picked up used guitars and sighting down the neck it's hard to tell. A straightedge from the nut to the saddle shows the problem (if there is one) by looking at where the straightedge meets the saddle (or bridge in some cases).

[devellis]

The string can work as a straight edge. The usual drill is to capo at the first fret, press down manually at the 14th fret (or wherever the neck joins the body), and measure the string's distance above the fret at mid-neck. But distance alone doesn't tell the whole story because string travel will vary depending on its tension and the player's aggressiveness. Too much measured relief for one situation may be too little for another, and vice versa. So, playing is also important to see if anything buzzes. Measuring, of course, is a good way of keeping track of where you've been and how much things have changed.

Larry, excellent observations. Weather changes can certainly cause a bunch of things to shift. I've never gotten much mileage, personally, out of truss rod adjustments but that may have as much to do with my lack of skills as anything else.

[head_guitar]

i don't think i have ever agreed with absolutely EVERYTHING Larry writes in a single thread, but i do this time. (i'm still trying to get over him calling my masterbilt "not high-end." And relative to his olsen, he's correct !!) If your guitar cannot handle an eighth to quarter turn tweek, then it needs some repair. the truss rod is not the proper way to adjust action, BUT, FOR MINOR ADJUSTMENTS, IT SURE DOES WORK A LOT.

[Howard Klepper]

Some people use the string for a straightedge, but relief can be set more accurately by using an actual good steel straightedge. Because of its stiffness, the string does not define a perfectly straight line when held down behind the frets. It also is easy to push it aside a couple of thousandths with the feeler gauge. Depends on how accurate you want to be. A lot of folks have an inflated idea of how much relief is needed. For most players on a well setup guitar, 4 to 6 thousandths of an inch is all, and a sensitive rod will allow adjustment in thousandths of an inch.