Truss rod adjustments

[Rodger Knox]

Originally Posted by charles Tauber

One should be aware that there are several different truss rod designs, some of which are more efficient than others. Single-acting and double-acting double-rod truss rods require very little turning of the nut to accomplish significant change in the neck curvature. Single-acting, single-rod truss rods, generally, require more.

Being able to identify the design of the truss rod enables the luthier to have a pretty good idea of how much adjustment may be required, but that's a trade secret that no one shares.

Originally Posted by charles Tauber

This comes up like clockwork.

I've been making and repairing guitars for more than three decades. Here is what I have done during that time, during which I've never broken, stripped or damaged a truss rod.

But for rare exceptions, when a guitar requires adjustment of the truss rod, I adjust it as much as is needed to obtain the target amount of neck relief I want. I make an adjustment, whenever possible with the strings on and at full tension, and observe the result of the adjustment. If I didn't get the target amount, I increase the adjustment. If I overshot the target, I reverse it slightly. If that takes 1/8 of a turn of the truss rod nut or 2 turns of the truss rod nut, so be it: achieving that target relief is the sole purpose of the (adjustable) truss rod and its reason for being there. It is VERY rare that further adjustment is required after that: that is, the amount of relief rarely changes in the following days.

The collective "conventional" on-line wisdom is that one should not make more than an 1/8 of a turn at a time, then wait 12 or 24 hours, re-check, then make more adjustment, if necessary, not exceeding 1/8 of a turn at a time. Wait another 12 or 24 hours, then do it again until one achieves the desired target. I don't do that and I don't know of any professional repair people who do either.

Suppose a truss rod nut required 1/2 a turn, total, to achieve the desired relief. At a rate of 1/8 turn per day, followed by a 12/24 hour wait, that would take 5 days to achieve the desired target and then check it again after the last adjustment. I know of no professional who does that. Nor do I know of any reason that a professional should.

The argument usually provided by collective conventional on-line wisdom is that it is safer to do it that way, particularly for novices. I don't disagree that it is very safe, very conservative, but that doesn't make it the "correct" way that one should adjust a truss rod. Do it that way if you like, for the reasons of safety, but if you know what you are doing, there is no reason to do it that way.

Adjusting a truss rod is usually a trivial adjustment. Diagnosing what adjustment is required isn't: does it need more or less relief, are the nut slots too high or low, is the saddle too high or low, is the fingerboard level, are some frets high...? The universal solve-all is not to "tweak" the truss rod - just because it is easy to do.

The only thing I have to add is the use of a couple of blocks and a clamp to flex the neck into the proper relief before adjusting the truss rod takes most of the stress of moving the neck off the truss rod. That isn't important if the rod is robust enough to move the neck against string tension, and most are when they are in good condition.

[justonwo]

I’ve always heard that you should just keep cranking until the guitar sounds good. I have a special impact wrench that I use for truss rod adjustments. Of course, after real tight comes real loose. One or two quick pulls on the trigger and you should be good. 600 ft lb impact with 1/2” drive is best.

[charles Tauber]

Originally Posted by llew

Just saying what I experienced?

Thanks for doing that.

Might be way different once the guitar is built? Just what I saw free standing.

There is little or no difference in behaviour between a free-standing truss rod and one embedded in a neck.

I've demonstrated to many customers the same thing that was demonstrated for you. It is helpful to their understanding of what a truss rod is and how it works.

[Brucebubs]

Originally Posted by justonwo

I’ve always heard that you should just keep cranking until the guitar sounds good. I have a special impact wrench that I use for truss rod adjustments. Of course, after real tight comes real loose. One or two quick pulls on the trigger and you should be good. 600 ft lb impact with 1/2” drive is best.

Is this yours?

[mdshax]

Originally Posted by charles Tauber

This comes up like clockwork.

I've been making and repairing guitars for more than three decades. Here is what I have done during that time, during which I've never broken, stripped or damaged a truss rod.

But for rare exceptions, when a guitar requires adjustment of the truss rod, I adjust it as much as is needed to obtain the target amount of neck relief I want. I make an adjustment, whenever possible with the strings on and at full tension, and observe the result of the adjustment. If I didn't get the target amount, I increase the adjustment. If I overshot the target, I reverse it slightly. If that takes 1/8 of a turn of the truss rod nut or 2 turns of the truss rod nut, so be it: achieving that target relief is the sole purpose of the (adjustable) truss rod and its reason for being there. It is VERY rare that further adjustment is required after that: that is, the amount of relief rarely changes in the following days.

The collective "conventional" on-line wisdom is that one should not make more than an 1/8 of a turn at a time, then wait 12 or 24 hours, re-check, then make more adjustment, if necessary, not exceeding 1/8 of a turn at a time. Wait another 12 or 24 hours, then do it again until one achieves the desired target. I don't do that and I don't know of any professional repair people who do either.

Suppose a truss rod nut required 1/2 a turn, total, to achieve the desired relief. At a rate of 1/8 turn per day, followed by a 12/24 hour wait, that would take 5 days to achieve the desired target and then check it again after the last adjustment. I know of no professional who does that. Nor do I know of any reason that a professional should.

The argument usually provided by collective conventional on-line wisdom is that it is safer to do it that way, particularly for novices. I don't disagree that it is very safe, very conservative, but that doesn't make it the "correct" way that one should adjust a truss rod. Do it that way if you like, for the reasons of safety, but if you know what you are doing, there is no reason to do it that way.

Adjusting a truss rod is usually a trivial adjustment. Diagnosing what adjustment is required isn't: does it need more or less relief, are the nut slots too high or low, is the saddle too high or low, is the fingerboard level, are some frets high...? The universal solve-all is not to "tweak" the truss rod - just because it is easy to do.

Thank you, finally. I've only ever needed to adjust a truss rod when I've completely changed string gauges on a guitar, but there have certainly been times when I've had to make more than 1/8 of a turn, sometimes quite a bit. The common wisdom seems to be that my guitars should explode into a thousand tiny pieces if I make more than a minor adjustment, so it's nice to hear a luthier dispell the myth.

[llew]

Originally Posted by charles Tauber

Thanks for doing that.



There is little or no difference in behaviour between a free-standing truss rod and one embedded in a neck.

I've demonstrated to many customers the same thing that was demonstrated for you. It is helpful to their understanding of what a truss rod is and how it works.

Sorry if I've made worse of an issue than I should have?

[justonwo]

Originally Posted by llew

Sorry if I've made worse of an issue than I should have?

Dude, we’re all learning. Don’t sweat it.

[charles Tauber]

Originally Posted by Rodger Knox

Being able to identify the design of the truss rod enables the luthier to have a pretty good idea of how much adjustment may be required, but that's a trade secret that no one shares.

The main distinction is between double and single rod designs. Gibson uses a single rod design and has an acorn/hex nut as do most single rod designs. Most double rod designs use an Allen key.

Aside from that, one can easily tell by how much one has to turn the nut in order to observe an effect: a lot, single rod; little, double rod.

"Trade secret" revealed.

[Rosewood99]

Originally Posted by Paleolith54

??? No one said anything about adjusting action. Unless I missed it.

Agreed, but the subject line was misleading.