Traditional Truss Rod, With No Bend?

[Jehle]

I've never actually installed a traditional truss rod, I've always used the double acting type. As an experiment I was going to try one AND put it in a straight channel down the neck. Before I do this (even though I'm just using cheap wood) I wanted to know if any of y'all have tried this.

I expect it will work, but not be very sensitive at all.

If you have seen the banjo building stuff at the back of the Earl Scruggs book, he installs an adjustable truss rod this way. So it's been done.

Thoughts?

[WezV]

If you have a slanted channel it might work - i dont think it will if it goes striaght down the neck

traditional truss rods work because the curve of the truss rod (forwards) wants to straighten out as they are tightened, which in turn curves the neck (backwards) as the rod gets straighter

is that going to happen if you tighten a straight rod?... i cant imagine it will do much more than compress each end! that may cause the neck to bow but it will be unpredictable in direction

[Setch]

It works fine, provided the rod is below the centre line of the neck. It won't be as responsive as a curved rod, but it still compresses the back of the neck, and exerts a force which acts against string tension.

[WezV]

Yeah, i think thats what i meant by a slanted channel - one that keeps it closer to the back of the neck and following the thickness taper of the neck to some degree.... Rather than just putting a straight rod in directly below the fretboard, which would be unpredictable at best

[Bainzy]

Until around 1960 Gibson used a straight channel for their truss rods, and they did what Wez suggested - the channel was angled so the rod was much deeper at the body end than at the headstock end. Right now I'm using something inbetween the two versions, instead of either a straight channel or a channel that dips in the middle, my channel is flat at the body end then around the 7th fret starts to curve upwards, ending up 1/8" higher at the other end.

[Jehle]

Interesting. Like I said before, I knew that it had been done. I also considered the unpredictable warp factor. It actually is starting to look like more trouble than it's worth to experiment with.

Truss rods are cheap, about $8 through Grizzly, and even less for the traditional threaded rod type. I'm just in the mood to futz with the design and see what else will work. I'm also trying to find that magic point between minimal work and minimal cost. A straight route and a dumb rod from home depot is about as cheap as it gets.

Meh, I may just do it and see what happens.

[Jehle]

Well, so far so good. I routed the neck last night. With the nuts and washers on either end, there's actually room to nudge the center of the rod down about 1/8" with a fillet. In my quest to make the dumbest truss rod ever, it actually curved anyway. I'll take a few pictures and post the experiement.

If it works, perhaps others can benefit from it because it's so mind numbingly simple and cheap. If it doesn't, we'll all be the wiser from it. Sometimes you learn more from failure than from success.

Fingers crossed,

[black_labb]

technically a flat truss rod would work, as when the strings pull the neck out, the truss rod would then be curved, but the curve would be so minimal and the truss rod would have to be tightened alot more than you would want to.

that makes for another useless post to get my mind off things i need to keep my mind on

[thegarehanman]

The thing about a straight rod vs. a curved rod that seems the most difficient, in my opinion, would be the fact that most of the force applied by a straight rod will be focused at the nuts at each end. Whereas a curved rod more evenly applies the force along the length of the neck. This might not be an issue, but I would imagine in a side by side test, you'd see that the curved rod neck is a bit more predictable in terms of truss rod adjustment.

Have you considered routing a flat bottomed channel for a curved truss rod, then taking a piece of wood wide enough to fill that channel, cutting a long curve in it, gluing the bottom piece into the neck, installing the truss rod, then gluing the top piece into the neck, which in turn gets planed down flush with the neck? I think this would be pretty quick and be much more optimal than a straight rod in an over sized (depth wise) channel.

peace,

russ

[Jehle]

And, that's exactly what I wound up doing. The route was straight, and I used some pieces to support the ends from the backside, and another piece in the center from above. I'm not sure that this is going to be the work of brilliance that I thought it was going to be.

But hey, I'm back on the board. That's gotta be worth something.

[thegarehanman]

jehle, the blocks at the ends and center will help the rod to act like a normal curved rod, but you're still isolating the force of the rod that's used to counteract the bending of the neck to only 3 spots, whereas a continuous curved strip more evenly distributes the force. Again, this may not make a noticeable difference, especially if you've got a well picked piece of timber for the neck.

[black_labb]

if you think about it, a truss rod that fiocus's the pressure near the nut, it would make a better match to the strings as that is pressure on the nut. idont think that makes it any better though

[thegarehanman]

It's not the pressure of the strings breaking over the nut that causes a neck to bow, it's the tension in the strings that's applied at the tuning machines.

[Jehle]

True, all true. I'm a physicist and I should know better. I will probably go with the curved inset, like you suggested, when it's all said and done. I suppose I can only blame my work with the cigar box guitars for making me do something the wrong way (knowingly) just to see if I can make something suitable when I know that there's a better and more proper way to do this.

BTW, congratulations on being featured on GuitarTree. Now I know what the "rg" means.

[Hitone]

I was surprised to see that Benedetto uses a straight truss rod in his book Making an Archtop Guitar. I guess it does work.

Personally, I always route a curve channel. I do like the idea of routing a straight channel and adding in the curve with a few glued in strips.

That would save me from always setting up a crazy curved jig.

Recently, I made a truss rod for my acoustic guitar using Jim Williams book. I bent the rod, made a bronze cap and used tape (I forget what kind) to wrap it. It works. I used it when I was fretting the guitar just two days ago. Now if I could only figure out how to make a 2-way truss rod.

Doe anyone know who manufactures truss rod's? Or fret wire for that matter?

Good topic Jehle!

[jay5]

Benedetto uses a curved rod in his book.

[Jehle]

I got to thinking about this more.

I thought about ditching the truss rod altogether. What I really want to try now is a truss "string". I saw a picture of something like this recently. It actually looked like a string anchored at the headstock, and then run down the back of the neck and then tensioned at the end of the body with another tuning peg. It was really odd looking, but that's what it looked like.

There's tons of problems with the design, but it's something fun (and funny) to play around with.