Gluing in truss rod?

[Michael Tulloch]

I'm currently unsure as to the question of gluing (epoxy or...) in the truss rod. Either the single or the double acting units. I've asked around before, and get about a 50-50 yes and no set of replys, with no explanation or reason why they do or don't. Last one I just epoxied the ends of a single acting rod (Martin type) into the channel of the neck before gluing on fretboard.

 I'm about to close another one up , (the new double acting Martin type) and need to understand / decide which is the method I'll use forever more. I don't really have an answer in the books on the subject that I have.

Is it true that both ways will work equally fine, and all I need to do is toss a coin?

Thank you.

Michael

[Tim Mace]

I don't think truss rods are to be glued in due to possibly having to adjust at some point after installing.Reenforcement rod (non-adj) should be.

[William F.Eden]

I just run some silacon calking in the bottom of the mortis....Just to stop the rattle. BILL.'''''''''''''''

[Tim Mace]

How about spraying rod on the part that gets channeled w/plasticoat to achieve same goal?Several coats 'til as nug fit?Jus' thinkin' out loud......

[Michael Tulloch]

I guess I'm looking for theory...like why one glues in or not glues in. Does rod need to "slip"indedendantly in it's space inside to be effective? Or glue it in completely to make it one whole mass.....which seems wrong to me (although there are those that do that, I'm told. Silicone seems good for taking any unwanted vibration out of the picture, I see that.

[Frank Ford]

Indeed, the adjustable truss rod MUST slide a bit in the slot in order to be effective. A two-way rod must also be able to rotate. So, for adjustable rods, the reason for glue is just as the guys above have suggested - to stop the rattle. I sometimes use regular rubber cement - the kind sold for gluing paper.

Remember to be sure there's plenty of grease on any threads - a bit of corrosion later on can cause truss rods to jam.

[Michael Tulloch]

Well ...that effectively answers my question...thank you Frank (that's twice this week) and Tim, Bill....for demystifying this nagging question.

Michael

[Robert Filippi]

In order to avoid confusion, I believe it should be noted here that the Martin single action rod with the aluminum U channel should be epoxied in. Stew Mac has good directions on their site, and if you read the reviews on the same page you will see why this rod is my personal favorite.

[Michael Tulloch]

Robert...I'm glad you chimed in. But, some confusion now surfaces again, and I'll ask this despite the fact that it should be more than clear to me. I read the Stew mac thing...and did build with this very rod on the last one. It's not done yet...so I have no idea how the neck acts so far. Glueing in the rod as they suggest...bonding the whole vershmeel together inside....this doesn't hinder the rod acting on the neck when need be? Just seems bonding that aluminum channel to the length of the neck would stiffen this up quite a bit. I'm not debatring here, but respectively asking...as I'm still trying to nail this down in my own head.

Thanks. Michael

[Tim Mace]

I'd consider the above as more a non-adj truss/reenforcement to prevent
neck from bowing .So I guess you are correct?It should be lighter wieghtwise than adj trusses....if that matters to someone.

[Robert Filippi]

If you clamp the U channel truss rod in a vise, you will be able to see how it operates. As you tighten the nut, you will see the rod bending. When glued in the channel (I use System 10 epoxy applied to the vertical walls of the channel), and the same force applied, the rod will bend, taking the neck with it, giving you the force needed to counteract the tension of the strings.

This is a little different than the Gibson rod which simply (but usually effectively) compresses the back side of the neck or two way rods which need to move laterally.

If you have assembled the neck in your current project (the one with the one way Martin rod) to the point of having your fretboard on, you should see movement as you adjust the rod even without strings on. If you failed to glue in the rod properly, it may still work, but first it will have to bend in the channel until it takes up any free play there might be in it. If it is not under tension in this situation, it won't work and it may rattle.

If you feel the rod in that project was not glued in properly, try this.
With the rod relaxed but the adjusting nut tightened until lightly seated, tap on the back of the neck. If you hear a rattle, try removing a fret in the middle and drill a shallow 1/16" hole where you calculate the edge of the channel is and inject a little thin super glue. If this does not work,or if you adjust to the max without noticing any movement, you may have to shim the adjusting nut or remove your fretboard.

It is very important NOT to remove the tape on the bottom of the rod before installing; it's there to keep the glue from gumming up the mechanism. It is also very important that the rod is installed dead even or very slightly below the top of the channel. (I use strips of thin pickguard material as a spacer which I remove after gluing.)

I have never used the StewMac suggestion of taping over the top of the channel before applying the glue for the fretboard, and all my rods work fine. so don't worry if you skipped that step. I will probably try Stew Mac's suggestion next time.

You are correct in assuming that gluing in the U channel its full length will result in a stiffer neck. This is, I think, one of its prime virtues. Neck stiffness has often been associated with something desirable for acoustic response (I'm no physicist). I can tell you that if you start with a straight stiff neck (of normal proportions) the stress of the strings will provide all the relief you'll need.

I notice that LMI has a Martin two way rod (this is the rod you are using for your current project?) which looks very similar to StewMac's Martin one way rod except for the adjusting nut. My guess is that it is glued in the same way, but I would ask them before installing.

Lastly, I should recommend that you should carefully examine and test any truss rod before installing

I hope I've helped with this discussion. With all the choices out there, and with subtle changes in design, I fear some of my observations might be outdated. (We didn't even touch on carbon fiber!) Please correct me if I have been inaccurate in any way. The important thing is that we all do this procedure correctly. If all the guitars that end up on my bench had truss rods that worked properly, wouldn't that be a "relief."

Robert

[Michael Tulloch]

Thank you Robert. I'm printing this reply of yours to save for my "building notes". I'll check the rod in the 1st one when it gets back from the finisher. The one I'm closing up now is the LMI 2 way Martin thing, and I see now they have a "how to install for idiots" relating to this unit on their site. They mention that "most builders do not glue these in, but it is wise to apply a bit of silicone to prevent unwanted vibratory influences. Don't think I'll go back to the aluminum channel job as I see it now.
I appreciate your long and detailed advice here. Your a pal!

michael