Carbon Fiber Reinforcement

[Gordon Bellerose]

I am in the middle of acquiring all the parts and pieces for a bass guitar.
I want to reinforce the neck with carbon fiber rods, and make it 3/4 thick at the nut, and 13/16 at the body joint.
I've been looking at the different rod dimensions available from LMI, and stewmac.
I'm thinking of a 3/16 wide by 1/4 tall by 24 long rod from LMI, but I don't have a 3/16 router bit.
I'm not even sure I can find one; but I also haven't really looked yet.

What size rods do all you bass builders use?

[David King]

Gordon,
I use two 1/8" x 1/2" bars which are much stiffer than the typical dimensions thanks to the extra width. I rip parallel slots 3/8" deep into the neck and matching slots 1/8" into the fingerboard on either side of the truss rod.
AllRed is the supplier. Here: http://dragonplate.com/ecart/product.asp?pID=697&cID=20

[Gordon Bellerose]

David,

Thanks for that info, and especially for that link. Way better prices!
How is that stuff to work with? Cutting and so on.

[Bob Gramann]

On my acoustic basses (with the joint at the 18th fret) I've used a 21 1/4" x 1/4 x3/8 double acting rod from LMI. I see now that the current one is a bit longer. What ever you get has to fit your neck. I always use a double acting rod because I can. You should have no problem getting a 3/16" router bit at any of the usual sources. Long ago, I did a neck with carbon fiber. I wasn't sufficiently impressed to do it again.

[David King]

Gordon,
I cut it with a little diamond water saw but it's just as easy to cut with a fine tooth hacksaw blade. I'm a little paranoid about the dust but a P95 mask and clean up with a damp sponge should be good enough if you aren't working with it every day. I cut diagonally for a 2" long bevel that more or less matches my table saw blade's diameter.

[Bob Gramann]

Excuse me, I misunderstood and thought you were talking about the adjustable rod between the carbon fiber rods. Please disregard my contribution.

[Gordon Bellerose]

All contributions are welcome Bob!

I also use 2 way rods in my guitars.
This bass will be a 5 string, and with the extra tension on the neck, I thought it might be a good idea to add a bit more support.

Thanks Dave for the info on cutting. I am curious as to why you cut the rod on the angle.
You say it is to match your saw blade. Do you use your table saw to cut the channel?

[David King]

Gordon,
I use the two outside blades from a dado set with a spacer between them to cut the slots. They are about 1/2" apart. Obviously it's important to have the slots in the neck line up with the slots in the fingerboard. I use a single single curved truss rod that pulls directly on the ends of the carbon fiber which eliminates some of the sensitivity to changes in the weather. The result is an extremely stiff neck but it requires a solid truss rod with a good amount of dip (.200") in the center.

[Chris Richards]

Hi Gordon....

Yes, I'm going down the same route and will be putting CF rods in the neck, there aren't many companies here that sell them but I've found one, I like the idea of locating them into the fretboard but don't have a table saw to do it, the neck will be a through body and I was thinking if I make it 5 piece I could table route the two thinner neck strips with a rebate to fit the cf rods before assembly of the neck. Still weighing up the options at the moment.

[Jason Rodgers]

David, I knew how you installed your CF bars, but didn't know you used a ganged blade (dado) to cut the slots. Clever, and accurate.

Chris, you could still install your CF bars as David does, but you'd need to either have a jig to cut the slots accurately and repeatably in both the neck shaft and fretboard, or size your neck and fretboard blanks the same and run them over one blade on the table saw with a fence (flip it for the other slot). It would take a little more thinking, but you could achieve the same results.

[Gordon Bellerose]

Hi Gordon....

Yes, I'm going down the same route and will be putting CF rods in the neck, there aren't many companies here that sell them but I've found one, I like the idea of locating them into the fretboard but don't have a table saw to do it, the neck will be a through body and I was thinking if I make it 5 piece I could table route the two thinner neck strips with a rebate to fit the cf rods before assembly of the neck. Still weighing up the options at the moment.

I use a router table for cutting the channels into a neck.
I mark both sides of the bit on the fence, and start the rout by tipping the neck down onto the bit using the fence as a guide. Then simply rout until I get to my end mark.
With a smaller bit, I will have to make smaller depth adjustments as I go.

If I didn't have a router table, I would build a jib to hold the neck, and guide the router from above.

I think you may have better luck routing after gluing up the neck, while the stock is still square and flat, but there are many ways to accomplish the same job.

[Chris Richards]

Thanks for the advice, not having a table saw can be a awkward at times. Yes I agree, gluing the neck parts together with pre routed channels for the CF rods would be an unnecessary complication, it is something I could do on my router table after the neck blank is glued-up....Typical of me I was thinking cheap and avoiding buying a specific router bit and just using what I had and routing a rebate down the edge of the thinner neck laminates!

[John Morciglio]

Hey all,
don't post much but this is kind of my area of expertise

IMO, the "rods" or small cross-section stuff from Stew-M or others are WAY too small to have
ANY effect on strength??? (just set one on something and test deflection if you are in doubt)
May even induce "dead zones" or "wolf notes" ???

The taller, 1/8 x 1/2" deep from Dragon Plate would be MUCH more effective. Again IMO.
Surprised at the decent pricing. (price a 1/4 x 12 x 12" plate) OUCH.

This is how I build all my "hybrid" necks;


Full carbon stringer front-to-back. Not effected by temp. or humidity.

Just use the "Martin" style truss rod w/ the U shaped AL (housing?) to straighten the necks.
Also start with .005 - .007" relief built in before fretting.

Tightening the rod will (just) get the necks flat w/ moderately to heavy string gauges.

Necks blanks are co-laminated with the carbon, epoxy and whatever woods I am using.

Use the same structure inside full carbon necks to house the truss rod.

[Alexander Higgins]

I used two 1/8" x 3/8" CF rods from Best Bass Gear, plus a DA rod in a neck through build. I left around 3/16" of wood under the CF rods to back of neck, so the rods limited how thin I could shave the neck. Some people think Its unnecessary for a 4 string, and I was a little concerned it would be TOO stiff, but that doesn't seem to be the case so far. As others have said, use gloves and a dust mast, the fibers are razor sharp. I used a metal cutoff blade.

[Chris Richards]

I suppose the alternative to using carbon fibre reinforcement would be to use two truss rods, what are the thoughts on this? I have no experience of necks constructed in this way, I can imagine not being able to accurately match the tension exerted by each of the truss rods may give rise to problems also you are replacing added stiffness with greater dynamic force. Just thinking about it I'm preferring the carbon fibre route...

[Barry Daniels]

You concerns are spot on. Two truss rods can be a big problem, and they are not necessary or recommended for a normal bass guitar. A couple of carbon fiber bars and one truss rod is better and results in a more stable neck. I use smaller carbon fiber bars than most folks. Mine are 0.092" thick and 1/4" high. These are guaranteed not to make the neck too stiff, but they definitely provide some stiffness and stability to any neck. I get the small bars from Dragon Plate.

[Gordon Bellerose]

I have heard of using two truss rods, but never tried it. Maybe it would work well for a multi-string bass (8 or 10 string) with a very wide neck.
My opinion for what it's worth, is that it may be unnecessary for a 5 string.

I have ordered the 1/8" x 1/2", and the 1/8" x 3/8" carbon fiber rods.
I'm going to check the 3/8 for deflection, to see if they might work.
I will most likely end up using the 1/2 inch, for this bass, and maybe I can use the 3/8 in a regular 6 string guitar.

[Alexander Higgins]

My current build is a Ric 4001bass tribute build, all Ric basses have two trussrods. I havent seen any real problems with two trussrods as far as neck stability, but I wanted to avoid the big truss rod adjustment pocket and no volute inherent to the standard Ric design. Its a real weak point in the neck. Having carved the neck with one DA rod and two CF rods, I didn't have any trouble dialing out the small backbow after fretting, so I'm hopeful the neck will be stable but easily adjustable under string tension.