Official Luthiers Forum!

Hi Guys,

I will be creating a flamed maple neck and am contemplating using carbon fiber rods on each side of the truss rod. (like example 2 in the picture). Is this overkill or not? I really don't want any neck issues down the road.

Best regards,
Ted

Carbon fiber rods are good, but the thing to watch out for is getting the neck too stiff. I like to use smaller rods. Something around 1/8" wide by 3/8" tall is plenty in my book.

I wonder if two carbon fiber rods are too stiff to allow any adjustment on the truss rod. For a regular scale 6string I would use either/or but not both. Maybe for a 12string or a bass with a long neck it would make sense??

If you use hard maple (also called rock maple, sugar maple) you won't need the CF bars - but it won't hurt to have them either. At standard neck thickness you will still be able to move the neck slightly with the truss rod.

In fact, with CF bars you can actually make the neck thinner at the same stiffness - my last neck was 0.75" (including the fretboard) at #1 and 0.85 at #12. But depending on what your hand prefers, thinner is not necessarily better.

#3 is stiffer than #2. Forget #1 (not adjustable) and #4 (overkill, too heavy).

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The member formerly known as erikbojerik....

Fillipo,

Too much carbon will keep your truss rod from working. I built a 6-string bass and added four fairly large carbon rods. I had to adjust the truss rod almost to the breaking point to get the new neck to move into proper relief. After 6-months, I had to dial the truss rod way back due to the earlier over compensation after the neck relaxed into a serious back bow.

Now I use two rods for steel string necks that are .092" wide by 1/4" high. Tiny little bars but they definitely add some goodness to the neck. And they don't fight my truss rod.

Careful!
1/8" x 3/8" CF has more than twice the beam strength of 3/16" x 1/4" for about the same weight!

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Dave
Milton, ON

Example #2 is what I use and I have had Zero issues with it. I still get the proper relief with less work for the truss rod. In other words the truss rod is still applying a counter active force against the string tension but with less effort.

BTW #2 is stiffer than #3
and #4 is more likely to be weaker than the rest at the head stock.

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Rich S

"The inconvenience of poor quality will linger long after the thrill of a bargain has been forgotten"

Doh - I remembered it backwards - #2 is definitely stronger than #3 - blame onset alzheimers.

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The member formerly known as erikbojerik....

Hi Guys,

Thanks for all the great feedback. Do you guys encapulated your carbon fiber rods with epoxy or silicon?

Best regards,
Ted

#2 has taller rods but they are closer to the middle where the neutral axis is. I think that the further out the bars go the more benefit it has in the long run for stability. So even though the bars are taller in #2 I think #3 is the best choice becasue they are spread out more. My feeling lately is that tubes laid as deep and as far out towards the edges as possible is the best choice. I have also been laying a small strip on its side under the truss rod. For a hard maple neck though, you probably don't need much.

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Burton
http://www.legeytinstruments.com
Brookline, MA.