To truss rod or not to truss rod

[Charles Bloss]

I know this subject has been beat to death but instead of using an adjustable double action truss rod in a neck, would two 1/16" x 1/4" steel bars be okay in place of a rod? I know it would not be adjustable in any way but I prefer to have a flat neck anyways. I was thinking of having them spaced about 1" apart in exact fit slots under the fingerboard. Any thoughts?

[Bill Raymond]

As you said, this subject has been beat near to death and most would probably advise you to use the truss rod. I'm not sure that steel bars of the size you indicate would be satisfactory. I've used 3 bars of aluminum alloy, 2029-T3, 1/8 inch wide and 1/2 inch deep and found it satisfactory. You might also, if weight is a consideration, put a series of 9/32 inch holes spaced 1/2 inch apart all along the strips--this doesn't appreciably weaken the reinforcement. Carbon fiber is also a possibility.

[Charles Bloss]

Im not set on the size yet. I have several different options available. One of the bars I had my hands on seems like it would work well but I wanted to get some opinions. I also have aluminum but it gives a bit too easy.

[Barry Daniels]

I have a 1/4" by 3/8" steel bar in my third guitar which is now 35 years old and it has been flat since day one. So it will definitely work. But the neck is a bit heavy. I now use single action truss rods that I make myself and I appreciate the ability to tweak the relief.

[Jens Moller]

The Original Danelectro guitars used 2 steel bars, like you described. They used Poplar for the necks. 50+ years later, few of these necks ever had any problems with warping. You can buy carbon fiber with about the same dimensions - it works well too.

[Christ Kacoyannakis]

I am all for the carbon fiber bars. They are three times as strong as steel, and weight less than the wood you remove to install them.

[Greg Robinson]

I am all for the carbon fiber bars. They are three times as strong as steel, and weight less than the wood you remove to install them.

Christ,
Just to correct what you have stated, extruded carbon fibre has three times the tensile strength of steel per unit weight. So although it is lighter, the same volume of carbon fibre is not nearly so strong as steel. Also, carbon fibre is heavier than any wood, so adding solid carbon fibre bars to a neck will increase its weight. If you use hollow carbon fibre tubing you can offset that fact and still achieve a stronger neck.

It's all a compromise. If you have limited dimension in which to add reinforcement, and need the greatest stiffness, but weight is not a big problem, then steel is the best choice. Very small dimensions of steel will give a very, very stiff neck, so the weight does not need to increase too dramatically.
If you need a lighter neck, then carbon fibre bars will make it more than stiff enough for our purposes, without increasing weight too much.
Hollow carbon fibre tubing of course will give an even lighter neck, with similar stiffness (given the same approximate outside dimensions).

[Christ Kacoyannakis]

i stand corrected! Thanks for the info.

[Jeff Highland]

If you decide to go with steel, do one central bar 1/8' wide by 1/2" deep. it will weigh the ame as the two 1/4" deep bars but be much stiffer

[David King]

I'd say 1/2" tall for sure but I bet you could get by with thinner stock, .040" x two for instance. Twice the height = 4x the stiffness whereas doubling the thickness only doubles the strength. Glue it in tight so you get some torsional rigidity from the wood on either side.

[Christ Kacoyannakis]

I was just rereading this thread, and I got to wondering, if you are going to put steel or carbon fiber in the neck, why would you not want it to be adjustable? I can tell you that in Greek bouzoukis, if you are making an instrument for a professional player, especially one from Greece, you can't put a truss rod in it. They just do not accept it. They really feel that it makes the neck too heavy, and even if you make one with and one without, and showed them the real difference, they would pick the one without the truss rod. However, having made Greek bouzoukis and archtop guitars, I can say that no matter how careful I was in making the neck and the fretboard, and leveling the frets, in the end, being able to turn the nut on the truss rod a quarter turn and get the neck 100 percent dead straight is so much better. It really boggles my mind that the bouzouki guys do not want this convenience. But I understand that if you want to sell them, you have to leave it off. Just wondering if there is something like that behind your question, or if you don't like truss rods for some reason?

[David Schwab]

I know it would not be adjustable in any way but I prefer to have a flat neck anyways.

The question is then, how do you keep it flat if you can't adjust it? Necks move after a while, even with truss rods, and it's good to be able to tweak it.