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Typically I have been installing 2 CF rods (1/8"x3/8") on either side of the TR on 14 fret acoustic as well as electric necks. In addition, these necks are 5 piece laminate construction.

To date, I have not used them on 12 fret necks with the rationale that a 5 piece laminated construct would suffice to provide the requisite stiffness and stability for such a short neck. I realize that I have no evidence to back up this practice and was wondering if anyone has information or data that might address the need.

I have been using the rods supplied by our friend and sponsor, Jim Watts of Los Alamos Composites and am very happy with their quality, consistency and performance.

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JJ
Napa, CA
http://www.DonohueGuitars.com

Why not use carbon fiber for 12 fret necks? They don't add that much to the cost of the instrument. The don't add much to the difficulty of making up the neck especially if you are already doing a 5 piece. They weigh about the same as the wood that was removed so they don't change the balance of the neck. I don't think they affect the tone though others may disagree on this point. I don't see any downside.

On the upside, it will be a stronger, stiffer neck.

I don't have any data that would show whether you need CF reinforcement or a 12 fret or not. But, then again, hard data on any other carbon fiber reinforced neck is pretty limited and apocryphal.

The ones I have sure weigh a lot more than wood.

Also, in the process of a recent major redesign of my boxes and necks, I subbed out a neck with CF bars for one without on my test body. Sounded different to me. Tighter and more brash with the CF. I'm not saying it would effect all instruments that way but that's the second time I've had that experience with mine.

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http://www.chassonguitars.com

I used two 1/8 x 3/8 bars on a 12 fret slothead neck run across the nut into the headstock. Two way TRSD truss rod.
It was a solid mahogany neck. Barely pulled into any relief ( about .003). You have to be careful not to run them too far into the headstock or they will interfere with the slot ramps.
I'm a big fan of carbon bars and I still use them on 12 fret necks but I'd level the fretboard with a little tension on the truss rod. It'll definitely be a mighty stiff neck.
With a short scale length and laminated neck you probably don't need them unless you are looking for a tonal effect.
Terry

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

I was wrong and you are right about the weight difference. The CF is so much lighter than steel that it felt about the same as wood. I just went down to the shop and cut a piece of mahogany to the same dimension as a piece of CF rod that I had and weighed them. 1/4 x 3/8 x 3" The carbon fiber was 7.0 grams and the mahogany was 2.7 grams. About 2.6 times heavier. This wasn't the lightest or heaviest piece of mahogany that I've seen so it seemed about average.

I don't know what you mean by the terms "tight" and "brash" when it comes to guitar sound but the neck does contribute to the sound and a different neck is likely to make some difference in the sound. Whether this difference is attributable to carbon fiber or in spite of it is hard to tell. The proper experiment would be to make a neck without cf attach it to a guitar body and play it. Measure the heck out of the sound and/or keep copious notes. Pop of the finger board and install CF rods and test the sound. I don't have the kind of tonal memory that allows me to do these experiments. I forget what the guitar used to sound like.

I'm not saying that you didn't hear a difference and I'm not saying that the difference wasn't because of the carbon fiber. I am saying that it might be premature to draw a conclusion.

I don't know what you mean by the terms "tight" and "brash" when it comes to guitar sound

Yep, talking about sound is tough. Another way of saying it might be more focus and less warmth, if that's any better.

The proper experiment would be to make a neck without cf attach it to a guitar body and play it. Measure the heck out of the sound and/or keep copious notes. Pop of the finger board and install CF rods and test the sound. I don't have the kind of tonal memory that allows me to do these experiments. I forget what the guitar used to sound like.

The two necks were about as identical as you can get. Same piece of wood, everything machined to pretty tight tolerences. Also, the new neck design comes off with 2 bolts so it was a pretty short time between playing each version. But it is absolutely subjective, as is all listening. But one thing that struck me...I wasn't even testing the necks for sound but for structure. I heard the difference (or thought I did) and it matched a perceived difference I heard the last time I put in CF bars.

Again, I'm not knocking the practice overall, just saying I don't like the effect it has on my guitars or the added weight.

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http://www.chassonguitars.com

JJ,
When Charles Fox gave a Master's Class at LINT this February, the one thing I resolved from his lectures was to incorporate CF in my necks from now on. (14 fret or otherwise.) Not for strength or stiffness, but because of the eveness/balance in tone he said it imparts all up and down the neck.

Now, Kent sounds an interesting caution about what he hears CF doing. I have only heard those comments about CF when used in laminated top braces. Could be so about necks too. Anyway--if you like the sound of a CF reinforced neck, I'd do it for that reason. I think you probably wouldn't need the extra stiffness, but you might want the sound.

Steve

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From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com

Interesting point, Steve and one I really noted on electric necks in particular. Perhaps because they are longer, they seem to respond more quickly and sustain forever. I've made 4 slotheads so far and none have CF rods. Of the four 14-Fretters I've built, all but one have CF...and there is a noticeable difference. Looks like I may try this in the next 12 Fretter. Thanks for the info and prompting this.

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JJ
Napa, CA
http://www.DonohueGuitars.com

And as always, JJ, let us know your results.

Steve

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From Nacogdoches...the oldest town in Texas.

http://www.stephenkinnaird.com