Official Luthiers Forum!

I have been inventing stuff again and this time I might have come up with a winner. Insetting a carbon fiber rod or rods in the neck has been done by lots of people, done it myself. This technique works and makes a really good product. I have taken this idea to the next logical level.


Making a three piece neck with 6 or 10oz. carbon fiber fabric laminations makes an extremely stiff neck. As the carbon goes all the way to the end of the headstock it should completely eliminate any snapoffs also.


I used West System epoxy for this lamination, be sure to use a respirator and gloves as epoxies are really nasty!

This blank was actually big enough to cut two necks when nested together. Add some wings and Bobs your uncle!

The finished product looks pretty cool, the stripes add a little pizazz!

If you make the center lamination (wood) strip narrow enough you could carry it all the way down your tenon or dovetail. Try it, the stiffness is amazing!!

Any feedback from the gang would be appreciated and carefully considered...

Mikey

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The Biggest Little City, Nevada
www.hammondguitars.com
I love building guitars!

So, looks like a black veneers strip when finished Michael? Why not? I get the monthly email from Dragonplate with their new products and it always gets my imagination going. They have a lot of cool stuff. Seriously though. How do you like the look under finish? Also, no problem with it fuzzing up when sanding? Will it sand consistent with the wood?

Thanks! I like the possibilities.

Cheers,
Danny

Michael,

That looks like a very good idea. I'm interested in the same things as Danny. Does it look more or less like black fiber once finished?

Also, what west systems epoxy and hardener did you go with?

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Joe Beaver
Maker of Sawdust

I did this exact thing on a few necks about five years back. The strip is as black as it gets under a finish. I used carbon fiber braided sleeving.

I'd suggest that, although it may be quite stiff, orienting the fiber on a 0-90 axis is not optimal given the applied cantilever load. Orienting the fiber on a 45 degree angle and then stretching it to the longitudinal axis of the neck would greatly improve the bending strength by using the fiber more efficiently.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Stuart: Have read a lot of your posts and have come to know you are quite knowledgeable in this field. Had to twist my mind for a second on this post but I got it. Thanks for all your input...!
Tom

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A person who has never made a mistake has never made anything!!!

Michael: Nice idea............kill two things with one stone. Thanks.
Tom

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A person who has never made a mistake has never made anything!!!

I interleaved a layer of carbon fiber cloth between layers of veneer when molding a back and side set. One down side I noticed was that when running the back halves over the jointer the CF made little nicks in the HSS knives. I have since switched to carbide knives, but I haven't repeated the experiment.

Good looking necks!

You're welcome.

I mentioned the carbon fiber braided sleeve but didn't emphasize how ideal this format is for neck reinforcement.

Since woven carbon fiber fabrics must be cut on a 45 degree angle, and then stretched to more orient the fiber against the load, three problems arise:

1. Cutting woven fabric at a 45 degree angle wastes a lot of expensive material. Woven fabric is the most expensive format when it comes to carbon fiber.

2. The cut edges fray quite easily.

3. Pulling the cut material risks destroying it by pulling it apart, making handling quite difficult.

Braided sleeve eliminates all these problems. Braided sleeve comes on a roll, has a continuous edge, and the harder you pull on it, the better the fibers orient considering this particular application.

Orienting the fiber on the 45 will increase the torsional stability of the neck as well as compared to fabric oriented on the 0-90.

http://www.braider.com/Products/Braided ... vings.aspx One of the institutional suppliers for braided sleeve....a fine organization.

I might also note that I used to own a Wardwell 144 carrier braiding machine and made my own sleeve in-house once upon a time.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Good to know.

What method did you use to carve your neck? What tools? Sharps, abrasives?

Its death on HSS.

I made several Long Range, Bench Rest, rifle stocks using redwood, carbon fiber cloth and West systems epoxy, then switched to sitka. looks cool but I realized a single layer of cloth between laminations really was not giving me that much extra stiffness. I made a couple with the 1/16th dragon plate sheet and it was a huge improvement.

You have got me thinking. What about using CF flat stock like this?
http://www.acpsales.com/.014-x-36-x-12-CL2.html

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Joe Beaver
Maker of Sawdust

A single uni-directional layer is technically better for bending strength on a guitar neck but the neck will be weaker torsionally.

Also...having the fiber tows interlocking, as they do in a braid or weave, renders the layer itself a great deal stronger. A better way to explain this is to ask you to imagine curing two flat pieces, one unidirectional and one woven cloth. When bending the cured cloth there is no particular bias but when bending the uni-directional layer it will break easily when bending against the fiber orientation. For this reason, stretched sleeving is best.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Stuart:
It sounds like you might have been doin' this composite stuff on a professional basis in the past, if so maybe I should sit up and pay attention. Having the fibers on a plus or minus 45 degree orientation seems like it would be advantageous for some of the bending moments. I was thinking that having the fibers full length would be the strongest for the most commonly expected bending "directions", simply up and down. Help me understand how shorter fibers at an angle would be more benefical considering that carbon is near worthless in compression. I honestly want to learn. Also you mentioned that you "used" to do this in your necks, why did you stop?

Thanks,
Mike

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The Biggest Little City, Nevada
www.hammondguitars.com
I love building guitars!

Stuart,
Thanks for your replies. Very helpful.
If I can impose upon you one more time... is this a good candidate for the application?
http://www.braider.com/Products/Zero-Un ... erial.aspx

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Joe Beaver
Maker of Sawdust

To the contrary, Joe.

1. It's a uni-directional tape that will be the most likely to delaminate between two laminated boards.

2. The binder is probably a polyester thread that could very well show on the exposed edge when sanded and finished. Uni-directional tapes made with binders are generally used sandwiched, and therefore hidden, between other woven layers...which serve to contain them and stabilize their fibers...forcing them to bear the intended tensile load. A braided product is best for a guitar neck laminate.

http://www.braider.com/Products/Braided ... vings.aspx .... then find ZW58L250X. Laying flat on a table and then stretched tight (braided sleeve works like a chinese finger torture ) this material is probably about 3 inches wide and about 1/32" thick and would be a better choice.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

What you did is going to be fine...and it certainly looks good....so don't worry.

To optimally use the fiber though is just a matter of orienting the fiber differently. You did what I drew in the top illustration. Note that all the fibers oriented vertically do next to nothing to support any kind of bending or torsional load. They are just taking up space.

The lower illustration shows what I mean. Note that the fiber was oriented on a 45 degree angle...but I stretched it to more orient the fibers along the neck. This way they all bear load against bending and torsion.

Btw...I made composite aircraft propellers for about twenty years.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I think Trevor mentions this technique in his book.

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

It'll put chips in carbide tooling, too.

I went back to all wood necks. The extra stiffness wasn't worth the extra aggro.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

I would hate to sand, saw, or plane the stuff.

I made a wooden pickguard for an Ibanez RG by laminating the back with 3 layers of fiberglass to make it resistant to cracking (such as if a tech screwed it down too hard) and trimmed it with a sanding drum. The fiberglass layer immediately stripped the drum of any useful abrasive and basically destroyed it after one use. I imagine it would also dull any tool blades or router bits... Also the dust makes wood dust look like play doh...

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Diamond coated abrasives are generally used in production with carbon or glass composites. I've drawn up many plans to embed carbon fiber into necks without exposing their edges....so they wouldn't have to be cut after the cure. Tough to do conventionally but cad/cam/cnc makes it relatively easy with proper planning. The idea is to mold carbon fiber into blind cavities when the neck laminates are glued....compression cavities being cut into the laminates ahead of time. This would allow continuous fiber to travel through to the headstock...a serious improvement to the strength of that otherwise delicate area.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Hi ya Mikey!

Forgive me please for being the contrary one here but I have some concerns.

I've been using CF for some years now in various applications in a guitar and it works very well for me. However the specific application has to be well thought out as to the potential downside of CF use. But you all know this.

More specifically necks benefit from both some ability to move and of course our ability to adjust that movement as we wish. Even more specifically, if the way that CF is employed makes the neck too stiff and a truss rod cannot overcome this stiffness it's going to be a nightmare to set up for various string guages. It's also going to be a nightmare to fret and adjust and induce relief as desired. Remember too that if one sells their stuff someday, like it or not, some whack-job repair guy like me may not understand what to do with what you have done.

Just like when folks ask if a truss rod is really necessary and just like when those on the repair side (and many builders too) weigh in that a truss rod is a "must have" doing anything that makes it so the rod can't work decreases the servicability of the instrument.

For years builders have employed CF but not as laminations all the way through the neck as we see here. Because the CF in these applications usually is seen beside the rod and not all the way through the neck the necks are still adjustable as needed although often more difficult to adjust.

With head stock breaks in our shop at present waiting for me to stop posting and get back to work.... I really like the way that you took the CF beyond the nut and this will likely make the instrument less likely to shed a head stock. Gibson could learn from this.....

But we still need to be able to manipulate the neck with the rod. Think of refrets, leveling the board, etc. If the neck cannot be manipulated you will be in the land of Martin pre-early-70's where compression fretting and what a PITA that can be is the only way to perhaps.... shape the neck. I say perhaps because I am not sure that even compression fretting could overcome the way that the CF is used in this example.

Remember that acoustic guitars are built largely as they are to be tools for musicians AND to hold together while still being lightly built enough to not sound like strings on concrete.

I'd be interested to know when you get further along with this one if there is any adjustability in the neck or if it's too stiff? Once the board is on you should be able to tell even off the box.

Sorry again to be the buzz kill here. These days I tend to view things a bit differently now that I see how guitars and ideas fail or not every single day.

On a positive note I love the look of a three piece neck with two black laminations!

Sound's like a good way to strengthen the short grain orientation of the head wood when not using a scarf joint.
Cool.

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