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Old 11-09-2019, 12:09 PM
codecontra codecontra is offline
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Default Loose truss rod nut??

I have been playing guitar for over 30 years and never dared adjust a truss rod. I always brought my guitars to a luthier. However I decided to take a shot at adjusting the truss rod on my Takamine EF341SC. The action was a bit high 4/32" and I figured a little tweak was all that was needed.

I have read over and over to go SLOWLY and only a 1/4 turn at a time. However I noticed that the nut was very loose and turning it even a half rotation made no difference in the action. I actually had to turn it quite a bit to even feel any tension. I probably turned a good few rotations before the action moved at all. Now it is at 3/32" and feels/plays quite nicely.

But it seems that the truss rod nut was completely loose. Is that normal or a problem I should have checked out?

Thanks for any thoughts or suggestions!
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Old 11-09-2019, 12:14 PM
L20A L20A is offline
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Good question.
Many newer built guitars now have a double action truss rod.
I have no idea how they work.
Someone please explain this for me.
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Old 11-09-2019, 12:36 PM
YamahaGuy YamahaGuy is offline
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Originally Posted by L20A View Post
Good question.
Many newer built guitars now have a double action truss rod.
I have no idea how they work.
Someone please explain this for me.
Turning in the clockwise direction tightens the nut on the truss rod and puts a bow in the neck.

Turning in the anti clockwise direction loosens the nut on the truss rod (and will have felt resistance, as with tightening) and puts a back bow in the neck. Whereas, with a traditional truss rod, this action allows the neck to back bow a bit, but turning the bolt will not apply more back bow than the neck will allow on its own.

With a two way truss rod, there is a spot in the middle where turning the bolt feels futile. Eventually the threads will take up the slack. And if not, then the nut will fall off because your guitar has a one way truss rod.
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Old 11-09-2019, 01:39 PM
L20A L20A is offline
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Does my 2014 Yamaha LL-16-12 have a double action truss rod?
When I loosened the nut counter clockwise it started to give me the bow that I wanted but then the nut became loose.
I didn't try to turn it more at that point.
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Old 11-09-2019, 01:55 PM
YamahaGuy YamahaGuy is offline
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Originally Posted by L20A View Post
Does my 2014 Yamaha LL-16-12 have a double action truss rod?
When I loosened the nut counter clockwise it started to give me the bow that I wanted but then the nut became loose.
I didn't try to turn it more at that point.
My ARE LL16M had one (dual action), so I bet yours does. Keep turning and I bet the slack gets taken up.
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  #6  
Old 11-09-2019, 02:54 PM
charles Tauber charles Tauber is online now
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Originally Posted by L20A View Post
Good question.
Many newer built guitars now have a double action truss rod.
I have no idea how they work.
Someone please explain this for me.
There are three general designs for guitar truss rods: single rod, double rod and double-acting double rod.

The single rod design is, as the name implies, a single rod that has one end fixed, usually a metal block embedded in the neck a little beyond the neck/body joint. At the other end, usually at the head, there is a threaded nut that is threaded onto the end of the rod. The nut usually presses against a washer that presses against wood of the neck. The rod is usually installed in a slightly curved slot in the neck so that tightening the nut on the rod attempts to pull the rod straight, taking the neck with it. Tightening the nut on the rod causes the neck to bow concave towards the fretted surface of the fingerboard. Loosening the nut has no effect once the tension in the rod is removed. It acts only in a single direction. This is an old design first invented and used by Gibson in the early part of the 1900's, and is still largely used by them. It is the least mechanically efficient of the designs and the one that breaks most often, though broken truss rods are relatively rare. Having the threaded nut bare on a washer that bares on (relatively soft) wood of the neck, it isn't uncommon to have the wood of the neck compress, resulting in the truss rod running out of travel. Being the least mechanically efficient, it requires more turns of the nut to achieve the desired adjustment.

The double rod design was introduced in the 1970's, I believe. The earliest versions of it were the simplest to explain. It consisted of one rod bent back on itself to form two adjacent rods, joined at the bend. The opposite end has two free ends, one of which is threaded and one that is not. The non-threaded end goes into a blind hole in a metal block. The threaded end passes through the block and has a nut threaded onto its end. The nut presses against the end of the block. The truss rod is installed straight in a straight channel in the neck, under the fingerboard. As the nut is tightened agains the block, it draws the threaded end of the rod through the block, shortening the rod. The other rod cannot get shorter and bends, taking the neck with it. Like the single rod design, it can only bend the neck in one direction: once the tension is taken off of the threaded rod, the truss rod doesn't accomplish anything. Hence, it is often called a single-acting, double rod. More modern versions of the rod eliminate the bend and use two separate rods, but work the same way. The double rod design requires relatively small adjustments of the nut to accomplish the desired effect.

The double-acting, double rod is a somewhat similar design to the single-acting double rod. Although there are a few different implementations, they all work on the same principle. The earliest designs are from the late 1990's, I believe. The double-acting, double rod uses two separate rods, as the name implies, and two metal blocks, one at each end of the truss rod. One of the rods is permanently attached to the two metal blocks - it's length is fixed. The other rod is threaded on both ends and threads into threaded holes in each block. A threaded nut is permanently attached (brazed or welded) to the threaded rod. Rotating the nut in one direction forces the blocks apart, causing the straight rod to bend, taking the neck with it. Rotating the nut in the opposite direction forces the blocks closer together, causing the straight rod to bend in the opposite direction, taking the neck with it. Thus, turning the nut one way caused the rod to bow in one direction while turning the nut in the opposite direction causes the rod to bow in the opposite direction. The truss rod is installed in a straight channel. Since the threaded nut is permanently attached to the threaded rod, it cannot become loose or be removed from the rod, unlike both of the other types of single-acting truss rods where the nut is not permanently attached. The mechanical advantage - and amount of rotation of the nut required - is similar to the single-acting, double rod truss rod.

In short, the basic principle behind any of the designs is to use a threaded nut on a threaded rod where rotating the nut on the rod causes a change in length of one or more rods. That change in length causes the truss rod to bend. Being embedded in the neck, the neck also bends.

Last edited by charles Tauber; 11-09-2019 at 03:04 PM.
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Old 11-09-2019, 04:12 PM
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justonwo justonwo is offline
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Quote:
Originally Posted by codecontra View Post
I have been playing guitar for over 30 years and never dared adjust a truss rod. I always brought my guitars to a luthier. However I decided to take a shot at adjusting the truss rod on my Takamine EF341SC. The action was a bit high 4/32" and I figured a little tweak was all that was needed.

I have read over and over to go SLOWLY and only a 1/4 turn at a time. However I noticed that the nut was very loose and turning it even a half rotation made no difference in the action. I actually had to turn it quite a bit to even feel any tension. I probably turned a good few rotations before the action moved at all. Now it is at 3/32" and feels/plays quite nicely.

But it seems that the truss rod nut was completely loose. Is that normal or a problem I should have checked out?

Thanks for any thoughts or suggestions!
Based on my quick search, it looks like your Tak probably has a two way rod. I wouldn’t worry about the multiple turns. Sometimes, if there is no mechanical load on the rod, it takes some turns to begins applying pressure against the resisting wood the rod is trying to straighten. As long as you proceed cautiously, no sweat. Once you feel significant resistance to turning, that’s when you need to be mindful.
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Old 11-09-2019, 05:27 PM
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blindboyjimi blindboyjimi is offline
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Quote:
Originally Posted by codecontra View Post
I have been playing guitar for over 30 years and never dared adjust a truss rod. I always brought my guitars to a luthier. However I decided to take a shot at adjusting the truss rod on my Takamine EF341SC. The action was a bit high 4/32" and I figured a little tweak was all that was needed.

I have read over and over to go SLOWLY and only a 1/4 turn at a time. However I noticed that the nut was very loose and turning it even a half rotation made no difference in the action. I actually had to turn it quite a bit to even feel any tension. I probably turned a good few rotations before the action moved at all. Now it is at 3/32" and feels/plays quite nicely.

But it seems that the truss rod nut was completely loose. Is that normal or a problem I should have checked out?

Thanks for any thoughts or suggestions!
First of all, you are approaching this incorrectly. There is so much incorrect information out there. Loosening or tightening a truss road is for RELIEF only, yes it can affect action but that is a side effect. Do not touch your adjustable truss rod unless your relief is off. The order is simple.

Relief: it should be nearly flat. Capo the first fret E string or hold it down with one finger and hold down the string on the fret where it joins the body (12, 13, or 14th fret). There should be just a hint of light under your bass E string or 0.004-0.008” at the mid fret (6th or 7th). That’s it. Don’t touch it again unless this measurement is off. I use 0.005”

Nut: the nut slots should be adjusted when new and anytime the frets are leveled. The nut slots should be at the fret height or a few thousandths higher. I have mine at fret height.

Saddle. This is where you adjust action. Measure the 12th fret action from the top of the fret to the bottom of the string. Take off or shim double that amount at the saddle to get your action where you want it. I use 0.090” bass and 0.060” treble. That’s pretty low and some who use a pick heavily will want higher. “3 & 2” is the standard for most techs. That’s 3/32” (0.094”) on the bass and 2/32” (0.063”) on the treble.

Relief, nut, saddle in that order.

Now if you don’t know which way your truss rod works the simple answer is it is there to counter act the tension of the strings. Normally tightening the truss rod puts back bow into the neck and loosening it lets the string tension create more bow. Simply place a tuner on your guitar. Tune the E. Tighten your truss rod nut 1/4 turn and you will see it sharpen the string (the string has more tension so you’ve lengthened the string or placed back bow into the neck) or you will see the E string go flatter, or you’ve loosened the string by creating more bow in the neck.

Hopefully that makes sense. Do not use the truss rod to lower action because it’ll throw off your real set up.

Relief, nut, saddle. That’s it.
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Last edited by blindboyjimi; 11-09-2019 at 05:36 PM.
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Old 11-09-2019, 08:34 PM
codecontra codecontra is offline
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Thanks, everyone, for all the information. Much appreciated!

Jim - point well taken and I will keep this in mind going forward. I checked my action as you indicated and it is right on the money now. The guitar also seems to feel and sound wonderfully so hopefully it just had a little too much relief that was corrected and I did not do any damage.
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