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I was hoping to find 1/4" wide truss rods. Looks like LMI has one that looks good, Truss Rod, double action welded nut, TRSDA

Any thoughts? I really do not want to use wider ones (like at Stew Mac).


Mike

That looks to be the same style as the ones from Allied, which are what I use. Best design out there, IMO. The price has gone up significantly, though I think they were $15 each for 6+ when I last ordered a few years ago.

I also use the Allied rods. Someone can correct me on this if I'm wrong, but I believe the thread on the current Allied rods is finer than what is used on the LMI rods (I haven't used a LMI rod in a while). They are similar rods and either of them would work for you.

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Josh House

Canadian Luthier Supply
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House Guitars - Custom Built Acoustic Instruments.
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I used to use Allied rods but the last few I've done were with Martin 2-way rods, they're 1/4" wide and appear to be bullet proof. They're easier to install and also use a larger hex wrench for adjustment.

I have to say though I always tested the Allied rods per the instructions and have never had a problem with them.

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Steve Smith
"Music is what feelings sound like"

Why don't people consider using the simple light weight single acting truss rod? Have y'all experienced a lot of back bowed necks? I can make a custom length 3/16th inch thick truss rod in about 20 minutes and for under $3. I've heard you can build some "double action" into the rod if you so desire, by slightly tensioning the rod and planing the neck flat. Theoretically, releasing the tension on the rod will give the neck some forward bow. I wouldn't bother unless it was a lightly strung electric.

There have been a number of times when I've needed to put a little up bow into a neck. While releasing the tension on a one-way rod should allow for some up-bow, I much prefer having control over exactly how much. Well worth the extra $15 you spend on a good two-way rod.

Steve, I'm not familiar with the Martin rod. How is it so much easier to install? I looked it up on there website but can't find any detailed info. And the pictures isn't that good.

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Josh House

Canadian Luthier Supply
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https://www.facebook.com/canadianluthiersupply?ref=hl
House Guitars - Custom Built Acoustic Instruments.
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Kinda wondered the same thing , although I have always used 2 way rods that I have purchased from Martin based on reccomendations from this forum ala , Mr Stock, and for really good reasons ..there are a whole lot of them out there, low to no failure rate and inexpensive at around 14 bucks a piece. I am not a pro but have 17 builds under my belt all steel string acoustics and have never had a reason to add in up bow to a neck, seems to be a good place to save some weight..it would be interesting to hear some more pros weigh in on this topic....

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MK5acoustics.com

That... is a good question The Gore/Gilet book recommends against them because they need the headstock adjustment point, plus add to the overall compressive load the neck has to deal with. But I like headstock adjustment anyway (mostly I think the cover looks cool ), and it doesn't seem like the compressive load on the neck is anywhere near enough to stress the wood. I'm always whining about how heavy truss rods are, so I'll give this a try before my likely inevitable arrival at the expensive, unadjustable, hard to install, but ultra-light carbon fiber D tubes talked about in that other thread.

Any tips or links to info on how to use them? Does it matter how deep it's embedded in the neck, or is the important thing how much curvature there is in the channel? Does the channel need to be round, or is square fine? Do they tend to rattle? I could wrap it in heat shrink tubing, but then it might not fit in the 3/16" slot cut by my plow plane...

And do you make them to order, or should I just buy from LMI for now?

Woah, woah woah!!!

Let's get clear about what is meant by double and single action here!

Double action is where you wind in one direction and the neck bends backwards and wind in the other directions and the neck bends forward. Single action is where you wind and you get more or less back bend, which is generally what you want.

Single action rods can be of folded construction as per my books, and likely a few others, which apply bending but no axial compression to the neck. Then there are the single piece rods, typically in a curved channel as per Gibson, Fender, Maton, et al, which apply tension to a curve rod to effect relief adjustment and perhaps a degree of neck angle adjustment depending on the nature of the geometry of the installation. These apply compression to the neck and seem to suffer the most from the maintenance point of view. Either the anchored end becomes unseated or loose, so you run out of adjustment, or the compression washer on the adjustment end compresses its seating and you run out of adjustment. The next step is the predictable over torquing and some sort of damage.

All types can be designed to be pretty bullet proof, but the folded style is more easily replaced if you so design it. If you do a double tenon style neck joint design which bolts on (no glue), it's quite easy to make a folded, single acting truss rod extractable, which has two advantages. You can change it if you manage to break it (seriously difficult!) or you can pull it and turn it over if you ever need to, so effectively you have a double acting rod without welds etc. to fail.

The folded rod is pretty easy to self-build; no welding required.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Many ways to do rods but avoid any that have the weld on the threads. I only use the Martin style or a simple compression rod. A single rod when do correctly can give you 2 way adjustments.

You can do this one of 2 ways. On a compression style you can put a little tension on the rod and then sand the neck true and attach the fretboard. This will allow a forward movement.
You can also put a slight back bow on the neck after fretting of about .010. Then level the frets. The string tension will pull the neck forward and if you need more adjustment you can release some tension off the rod.
Not all 2 way rods are equal. What make the martin style more robust and reliable is the construction. The adjusting nut is in a cylinder. Thus the welded area is off the threads . It also has a larger weld area and the welds are not at a point of shear stress. As a Martin repair center I have not seen one of these fail as of yet. They are a very good design.
I have had 3 fail all were welded or silver soldered to the threads .

As Trevor points out they can be made to be bullet proof . You can make them pretty easy. Wayne Henderson uses a compression style. Use what you feel most comfortable with, but do look into the reliability , replacing a truss rod is not a fun thing,

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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 wouldn't say so much easier but it is easier. No filler strip is needed which saves a step. And they are wrapped with a shrink-on plastic so you just put it in the slot with some PVA (titebond, etc.), glue on the fretboard and clamp.

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Steve Smith
"Music is what feelings sound like"

i use these. they work fine for me. i have to file the weld off the sides of the beam though, because at the weld they are wider then .25
i also like the shrink wrap on the rod as well.

Martin's Guitar Makers Connection lists two rods styles from what I can make from the photos:
Two way adjustable, 13BAR0001 @$13.00.

And the:

Adj. truss rod -14 fret. 13BAR. @ $13.00 which looks to be a U Channel style.
My question is which of these two rods is the one being discussed here and getting the good reports like being bulletproof, etc.
Thanks.



Sent from my iPad using Tapatalk 2

For my single action rods I put the adjusting nut at the heel end of the neck to avoid a loss of strength at the peghead. I drill a hole through the neck block for access. I wrap my rods in teflon tape to keep them free of any glue that might stick to them when gluing in the filler strip. It doesn't add a lot to the thickness. The rod should be located toward the back of the neck, but needs some wood under it (1/4 in.+). The channel should be a close fit to the rod, but from what people have said a flat bottom works as well as a rounded bottom (but it only takes a few minutes to scrape a rounded bottom into the trench). I've also read that a straight channel works about as well as a curved one, but those I do generally have a bit of curve in them - I like to have a little extra wood in the area under the first fret (adjustment nut at heel).
I'm not saying a traditional rod is the only way to go, but it is probably one of the lightest solutions for those that want an adjustable truss rod.

"Avoid any that have welds on the threads."

Not sure why you would say this John. A proper weld will be as strong or stronger than a 3/16 stainless rod.
I have made close to 4,000 rods over the last 5 years. The are all a 3/16 stainless rod with a hex nut that has been welded on. There has been no failures and in initial stress testing, actually over stressing the rods to breakage, the rod failed before the weld. Without exception. This design also eliminates the neck blowouts by the nut from over tensioning. They are 1 rod with double action compression rods and require either special fixturing or a CNC to rout the channel. They are being used, and have been for more than 5 years, in guitars that sell in the $3500-$25000 range.
Welded rods get a bad rap because of the people doing the welding. Not because of a flaw in the process. Most of this misinformation came about when the rods were manufactured in China to save money to sell to all of us at a cheaper cost. ( not cheaper when they fail ).
Just sayin that if you have a good welder and good execution you will eliminate most of your problems. Just like using any other craftsman.

Don't overlook the Cadillac of 1/4" two way rods, the handmade Blanchard. A little more expensive but this is one area you don't want to pinch pennies.

I took one of those Martin style 1/4" two way rods apart a few years ago and they look tough as nails. Don't think failure would ever be a problem. I would worry about the extra wood removal required for the nut in a headstock adjustable rod.

I have been the unfortunate victim of weld failure in a Chinese made two way in a brand new guitar 5 or 6 years ago. Further stress testing of my supply at that time caused weld failure in 40%. It is my understanding that that issue was successfully delt with by the vendor.

I currently use the Blanchard rod and love it.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Ok the 2 way rods are threaded and the welding is done on the threaded sections. As a tool maker and engineer ,. what can happen is the metallurgical properties are changed in the welding process and with the threaded area in the heated zone, the bottom of the thread is considerable smaller than the 3/16 diameter plus there is a stress riser issue .
Welds when pulled or pushed have a lower stress then when torqued . This is where I can say you will have the issue. The fact that so many have failed is proof of this. It is a flaw in the process and once the metal become heated and not cooled properly that stress riser will snap them like a twig.
If you are making your own rods and you are controlling your process It may be fine but we are speaking mostly of the Chinese produced parts that are commonly sold not custom private material. The alloys used can also be a factor as not all steel is the same.

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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

John, are the Martin rods you use the same ones available at the Martin Guitar Makers Connection? Are they available elsewhere? Sorry to get off track.

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

I use some martin and I also get them for the supplier. Same design.

I like these as they also remove less wood out of the neck for the channel. The old U channel 1 way design use a 7/16 channel .

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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

That large wood removal is why I am not using those I saw at several suppliers.

The reason a lot of people like the Allied rod is it is unique in the way it works. Most double acting rods have a right hand thread at one end and a left hand thread at the other. So turning one way tries to elongate the flat rod and turning the other way tries to shorten it, thus making the assembly bend one way or the other.
The allied rod has a coarse right hand thread at one end and a fine right hand thread at the other. So when you turn the threaded rod the square section 'nuts' welded to the flat rod move different distances, getting closer together one way and further apart the other. It's a method used in engineering to produce the equivalent of a very fine thread without the weakness that very fine thread would have.
The result is a truss rod which requires much less torque to turn it and has much finer adjustment in about a 6 to 1 ratio compared with left-hand right-hand threaded rods.

That's the Blanchard design that was mentioned earlier. Mark sells and makes, to order, the same rod only higher quality.
I recently purchased one of his and I can attest to the high quality which, fair enough, comes with a higher price tag.

+1 for Mark Blanchard. What I really like about it is that he will make them any length you want.

I do like the action of the Allied rod although QC is a little sketchy. Does anyone know if the Martin 1/4" rod is a left/right thread design? Is it made in China also?

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Pat