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I understand from another forum that Martin no longer uses a U channel truss rod. I have been using the Martin style U channel rods as sold by Stew- Mac and love them. Epoxy them in and they make a stiff neck. They are a one way rod but I can't figure why one needs a two way rod in the firstplace. Given the problems of weld breakage in a different type of rod in another post, I wonder if I'm missing something by using this type of rod? Are folks having problems with it also....?
Tom

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A person who has never made a mistake has never made anything!!!

The one-way, aluminum channel "Martin style" rods is all I've used for the past 12-13 years. I've never needed a 2-way rod, and never have issues with these rods breaking. I glue them in place with polyurethane glue, and going against all common wisdom, I peel-off the masking tape, exposing the underside of the rod. I use a generous amount of the poly glue, and allow the foam to completely fill the rod to channel cavity, further stiffening the system, and eliminating any chance of a rattle or unintended harmonics or whatnot. I've not had any issues with adjustments; the rod remains very responsive to the slightest input.

It's a dead-simple and 100% reliable truss rod system. What's not to love?

Are the new Martin 2-way rods aluminum?

with a one way rod you tweak the rod with about .006 back bow and plane flat, This affords a forward adjustment and keeps the rod in tension. I prefer Tee bar and 1 way rods but consumers think the 2 way is better. It is all in the marketing I guess. I do use Martin 2 way rods and nothing else in that department.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I've been wanting to try the Martin 2 way rods, but there's just no way I will pay $16.00 to ship a $14.00 item. I'll stick with the 1 ways from StewMac.

Like Mario says, they work great. And I don't have to pay that extra shipping cost.

-Mark

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Pullman, WA

The more I know, the more I know I don't know.

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Todd: My first 20 or so were built with a non adjustable rod and it was not a very big problem to get the neck in the right configeration by using a bit of built in back bow. Grit Laskin did that for a long period of time and maybe still does. As to refrets it's the same thing,one has to be aware not to build in extra back bow.Guess Matin wants to be extra sure,but it seems we get all caught up in it as well. Long live the U channel rod.
Tom

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A person who has never made a mistake has never made anything!!!

Can someone weigh, accurately, the "new" Martin 2-way rods? Sounds like they're heavier, too...

BTW I'm a BIG fan of solid, non-adjustable necks, too. Nothing I own has an adjustable rod, and I offer it as a no-cost option, but precious few clients ever go for it....

Wish we had a good source for T bars!

I like the Gotoh U channel rods too, very stiff and found that it can allow negative adjustment too (I cranked it the other way and caused the neck to increase its relief without any string tension). It's probably impossible to break the rod (as in you'll break the neck before you break the rod). The only downside is that this truss rod is very heavy. It weights enough to tip the neck forward if the neck wood is heavy enough. Sapele is a big problem due to its higher density.

I haven't tried the aluminum rod from Stewmac, but I imagine it must be much lighter than the steel one.

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14 fret Martin 2 way rod is 141 grams or about 5 0z.
12 fret Martin 2 way rod is 129 grams or 4.6 oz.

Chuck

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As I suspected..... A little over 21 grams more than the one-way system. The SM aluminum U channel rod(14-1/4") weighs-in at 119.6 grams.

Tai, if you turned the adjustment nut backward and it worked as you said it did, you have the steel U channel 2-way Gotoh rod. With a one-way rod, the nut will simply come right off if you turn it backward(IE: loosen it). I used some of those rods early in my career(mid-late 90's) and have had to replace about a dozen of them by now. I truly hope they're better today than they were then! And yes, they were heavier than the aluminum u channel rod.

Does anyone epoxy the 2-way Martin rod in place?

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Formerly known as Adaboy.......

I'm pretty new to this "hobby" & never thought much about truss rods. I always assumed 2-way was better but didn't realize that they are more susceptible to failure and weight more.

Are 2-way rods just another "improvement" by the guitar factories to reduce the cost of warranty repairs resulting from shoddy construction and/or owner abuse?

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

you at one point tried the Gotoh-like two-ways and found them wanting...what was the motivation?

Young, inexperienced(no literature, not even internet yet) luthier, looking for an easier way to do things....

May I suggest that when you re-fret a neck that was otherwise straight beforehand and then ends in a backbow, that you chose a fret with a too-wide tang? I can't see any other reason? And no, I've not yet run across a neck that needed a two-way rod torqued in reverse. Maybe it's more common on electric guitars and basses, but I've not seen an acoustic with the malady yet, so my take will remain that a 2-way rod in an acoustic guitar neck is a means of getting around poorly seasoned woods, mis-informed glue choice, or construction/workmanship issues(or all of the above). Oh, and ease of setup and/or factory floor time-saver.

I have a video(remember VHS? <lol>) from the late 80's where Chris Martin admits they experienced fewer warranty claims with their solid, non-adjustable necks than they were presently seeing with their adjustable necks, but they had to bow to consumer demand for the adjustable system. Leo fender was another who was dead-set against adjustable truss rods, but again, consumers demanded one. My logbook shows much the same; while a non-adjustable neck is a no-cost option(and I hold steadfast that they also sound better), less than 10% of my clients will opt for one. And yet(other than an early experiment with CF-only reinforcement that proved too weak) zero, nada, none of the solid necks have ever had an issue and have held their relief just fine. A perfect track record, especially when compared to the 12 or so of the 15, 2-way rods I used that needed replacement.....

I have been using the SM Hot Rod, 2-way which weighs 105 grams. So far I have had no problems with them. Have any of you experienced problems with these. My motivation for using them was that they were the lightest ones I could find. I did not see the 2 way adjustment as a big advantage, but didn't figure that it would be a disadvantage either. I tried the old Gibson style rod on some of my earlier builds, but I was never confident that they would perform properly.

Mario, did I read your post correctly that the CF reinforced necks were too weak? How do your stiffen the neck on your non-adjustable option?


James

I am with Grumpy here. To be honest the best rod that I liked is the Gibson design. It is the one Wayne Henderson uses. It is light and dependable. Also the moment you tighten it you have the neck in tension where the U channel pushes up on the fretboard and down on the neck.
Use the proper fret tang and adjust a small back bow you will have more adjustability thank you need,

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

did I read your post correctly that the CF reinforced necks were too weak? How do your stiffen the neck on your non-adjustable option?

Steel.

CF is stiffer than steel, BY WEIGHT, but we can't get enough CF into a neck to make it stiff enough; just not enough room. Steel is much more efficient in this configuration..

Mmm...I guess I do too much repair work.

Not necessarily; methinks you're either not using proper refretting techniques, and/or not completely understanding the dynamics of a loaded(stressed) guitar neck. Nothing to be ashamed of, but like in any recovery, the first step is to admit we don't understand everything and admit we need help. In this case, if every time you run across a neck that has too much backbow, you throw-up your arms and say "why didn't the idiots install a 2-way truss rod from the get-go!!), then you've defeated yourself before you even got started. Instead, you need to ask yourself "well, I'm sure the idiot who built this guitar didn't send it out with a backbowed neck, so, what the he!! caused the backbow, and how do I correct it"?.

Also the moment you tighten it you have the neck in tension where the U channel pushes up on the fretboard and down on the neck.

Incorrect.

The one-way U-channel rods work the ---exact--- same way that the original Gibson rods do. Take one apart and you'll find a small spacer in the middle of the channel; this spacer forces the rod into a bowed shape, same as a Gibson rod system does. When we tighten the rod, it wants to straighten itself(to see how this works, just hold a string in each hand, held apart such that the string is sagging; now, pull each hand away from the other to tighten the string, and see what happens. Right! The sagging string straightened up! THAT is how a Gibson rod, as well as a one-way U channel rod, works). Thereby, the forces at work here are the same, as long as the U channel is glued-in solidly. The absolute only difference between the two is that the Gibson system acts directly on the neck's wood surrounding the rod, where the U channel system acts first(directly) on the aluminum channel, which is itself solidly glued to the neck's wood; thereby acting in the exact same manner.

Same. Exact. Physics. Only difference is that the U channel adds some stiffness to the whole of the neck....

I think the most interesting old Martin rod was their 3/8"x3/8" hollow steel tube -- much stiffer than a T-bar or U-channel in torsion. But maybe twist-warped necks are so rare that's not important?

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David Malicky

Yessir, the tube is stiffer in torsion, but the T bar was stiffer where it counts, and also left much more wood for carving. We typically see more relief issues with the square tube Martins than we do with the T bar models, though many of us feel that the real culprit is that they appear to have glued the tube into the neck simply with PVA(Titebond?) glues, where the T bars were fixed with HHG. Same with the fretboard; PVA VS HHG, meaning that the PVA glued-up necks can cold creep where HHG won't.

These days, I use a thin-wall 1/2" square steel tube for guitars, but for mandolins, I have to use a 3/8" tube, since a 1/2" tube won't allow the carving of a typical mandolin neck; the T bar was especially ideal for mandolins...! All glued into a tight-fitting channel with poly glue(zero creep).

Mario, for the uninitiated amongst us, could you post a pic of the t-bar you're referencing?

Steve

Thanks, Mario--interesting. How much flex relief do you get with the 1/2" steel tube?

Using some info on the T bar... http://theunofficialmartinguitarforum.y ... pic/137207 http://theunofficialmartinguitarforum.y ... ock?page=2 ...
for the 0.5" tall version, I get a moment of inertia of .0019 in4, which is indeed a bit heftier than the 3/8" tube (I assume it's 0.065" wall), at .0013 in4. The 1/2" tube comes in at 0.0036 in4.

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David Malicky

Twist is quite rare in mahogany necks, and is usually because a bad piece of wood was used.
I have used the aluminum channel Martin style rods since the mid-1980's, and I have yet to have a problem.
For years, my main complaint with two-way rods has been that they are too sensitive. Having left-hand threads on one end doubles the reaction to a given input. That problem has been solved with the Allied style of two-way rod, which uses right-hand threads on both ends.....coarse thread on one end, fine on the other. That makes the reaction very slow, which IMHO is preferable. The two-way rod is a bit trickier to install, because the rod attached to the adjusting nut must be free to turn.
The beauty of the tee bar is that it is held in place by the thin top web. Unlike the square tube, that shallow channel does not change dimension much at all under changing moisture conditions. If the channel is closely fitted, the tee bar cannot move, even without glue.

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John

One trouble I have with 2 way rods is that its harder to tell which way the neck is going when adjusting it. You have to have a straight edge on your neck at all times when adjusting a 2 way rod, so that you know which way its going. I had times where I almost damaged customer's guitar just because of 2 way rods...

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Yessir, we all have opinions and have a right to state them.

But I'll still argue against your assessment that " those preferring T bar and one-way are likely in the minority". While those who prefer solid, non-adjustable necks are indeed a minority, I suspect the majority of luthiers and manufacturers still prefer and use one-way rods, and most players really don't care one way or the other, as long as the instrument plays well.

If I was building a guitar with a truss rod,
I would make a one way.
3/16" rod that I thread.
Done a few that way,
with no problems.
Some players are WAY pickier than others,
about string action.

If I was building a guitar with a truss rod,
I would make a one way.
3/16" rod that I thread.
Done a few that way,
with no problems.
Some players are WAY pickier than others,
about string action.

Dang double post!!!!!!!!!