Official Luthiers Forum!

What do you use and why?

Clearly if a guitar neck is designed and built in a certain way, all you would need is a one way rod to correct for two much forward bow.

The strength of the wood and it's tendency to bow under tension is obviously another factor. If you're making a guitar neck out of doug fir, a one way truss rod is all you would ever need.

However, if you built a neck out of quartersawn maple if would be more risky to use only a way one truss rod because the neck will not bow much, if at all, under string tension.

I have seen people radius relief into necks that use one way truss rods by putting backbow into the neck before radiusing. This is particularly important for hard maple necks.

I can see two way truss rods being a safe all around option, particularly for beginners. They are more expensive.

One way truss rods seem to be more suited for seasoned builders who know for a fact that they would never have to put more forward bow, relief, into their necks. All you are concerned with is the option to reduce the amount of relief.

I have only used two way truss rods so far (ten guitars) and I am thinking of switching to using one way rods.

Oh really? I apologize if there was.

I see a few threads regarding truss rods, but not specifically about two way versus one way.

I use a two way because I've been doing repairs for years, in pretty busy stores. I've seen too many one way truss rod failures to think that they're a good idea for the custom builder. I know, there's some pretty heavy hitters out there who INSIST that one way truss rods are the only good rods for tone, but I've not met anyone who can listen to a recording and tell me what kind of truss rod is in the guitar.
It sucks telling someone that their $10,000 {Insert High End Builder} has a permanent back bow because their neck has moved beyond the capability of the truss rod to relax.
I've had to do that a few times.

_________________
Old growth, shmold growth!

No problem, here it is
viewtopic.php?f=10101&t=37387

Kevin Looker

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

A two way truss rod is much easier to install, and I think that's important for the first few builds. My first rod was a one way rod, I installed it incorrectly, and it didn't work worth a hoot. You can switch to a straight rod when you have the rest of the process under your belt. A truss rod that doesn't work properly is one of those things that can be extremely difficult to recover from, and for a beginner it's likely a fatal mistake. Ditto for a screwed up neck angle, and why I would always recommend starting with a bolt on neck and two way rod for number 1.

John,

Would you care to elaborate on exactly you did wrong so that it didn't work? There was a lot of chatter on the other thread about 1-way vs. 2-way but I think I missed the potential pitfalls if one chooses a 1-way.

Thanks,
Kevin Looker

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

I was afraid of breaking through the back, so I didn't install it low enough. I tried to put a curve in the channel, but didn't do that very well either. I exited the neck a bit too high, and had very little bearing surface for the washer....I ended up mostly crushing wood instead of actually tightening the rod. All stupid beginner mistakes, and all stuff I COULD have gotten right the first time, but I just didn't really know what I was doing!

The major downfall to a one way rod is if the neck back bows, you're SOL. The neck almost always wants to back bow a bit after gluing on the fingerboard, and generally does all sorts of random and not so random wandering around after carving. Typically, you fix it all up when you true/radius the fingerboard and frets, and some guys will do this with tensions on the rod and an intentional back bow to give them some degree of two way adjustment. So this would apply to any one way rod.

The Gibson style one way rod (i.e. just a simple rod with some sort of anchor on one end and threads on the other end) has more potential issues because it depends on it's installation geometry and relationship with the neck to work. I can put a Martin rod, or any 2 way rod, anywhere in the neck and it will function. There's only a handful of ways to install a Gibson style rod so that it actually works. You either need to put it right at the very back of the neck, and rely on the differential compression of the neck in order for it to function, or you install it with a curve and rely on tension trying to straighten the rod for it to function. The curved way works a lot better. Either way doesn't really leave a lot of room for error. It's not difficult, but the Martin rods and 2 way rods are so much easier to install, and so long as they don't break they will absolutely function properly at least.

Personally, I'm just going through my last couple of 2 way rods and I'm switching back to the Gibson style. I may change my mind again next year. There's just something about the simplicity of the Gibson rod that I find attractive.

Thanks John.

That's some good information.

Kevin Looker

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