Gluing carbon fiber to wood with Titebond

[Martijn]

Hi everyone,

In my next build I am going to use two carbon fiber neck reinforcement strips.
I have never used epoxy before. As the availability of expoxy is not very good over here, and I will probably don't need it for anything else, I prefer to use Titebond.
The StewMac website tells me it is indeed possible to use normal wood glue: http://www.stewmac.com/How-To/Online...Materials.html
But this does not match with the information I found in a lot of forum discussions I have seen about gluing carbon fiber to wood.
What is your experience?

[LouieAtienza]

I can only guess that since the CF is held captive by the neck and fingerboard wood, it may be OK. I don`t know if I would trust it, long term...

[Rodger Knox]

Originally Posted by LouieAtienza

I can only guess that since the CF is held captive by the neck and fingerboard wood, it may be OK. I don`t know if I would trust it, long term...

Louie's got it right on. If your CF reinforcement strips are completely covered by the wood, Tightbond will keep it from rattling. I did a long scale 5 string bass with 1/8"x 3/8" bars, the bars were essentially inlaid into the outside laminations prior to gluing, all done with Tightbond.

I wouldn't trust Tightbond to hold CF to wood in a lamination, but for buried reinforcement it works OK.

[printer2]

Used white glue to glue CF onto RC airplane spars and never had a failure.

[WaddyT]

Most all of the builders I know who use CF use epoxy to do the gluing. The glue has to stick to the CF or it doesn't perform it's service. I don't think Titebond would stick to CF.

[LouieAtienza]

If the surface is rough enough it will "stick," however it won't hold like epoxy. And if it isn't bonded fully to the wood as a unit, then it's pointless to use it.

[printer2]

Originally Posted by WaddyT

Most all of the builders I know who use CF use epoxy to do the gluing. The glue has to stick to the CF or it doesn't perform it's service. I don't think Titebond would stick to CF.

Actually come to think of it I think I used CA on the RC stuff.

[John Arnold]

CA or epoxy are my primary choices for installing CF neck reinforcement. If I wanted to use wood glue, it would be hot hide glue, not Titebond.
I continue to be impressed at how HHG sticks nonporous materials to wood..........including the steel tee bars that I have used lately.

[70man]

Originally Posted by Martijn

Hi everyone,

In my next build I am going to use two carbon fiber neck reinforcement strips.
I have never used epoxy before. As the availability of expoxy is not very good over here, and I will probably don't need it for anything else, I prefer to use Titebond.
The StewMac website tells me it is indeed possible to use normal wood glue: http://www.stewmac.com/How-To/Online...Materials.html
But this does not match with the information I found in a lot of forum discussions I have seen about gluing carbon fiber to wood.
What is your experience?

West system epoxy is the way to go,with micro-spheres added as a filler.Any good ship chandler would have them.Don't use vinylester or polyester.
And wear a mask and latex or rubber gloves when you use the stuff.You should also wear some sort of dust or respirator mask when you cut or sand the carbon rods too.

[printer2]

Originally Posted by 70man

West system epoxy is the way to go,with micro-spheres added as a filler.Any good ship chandler would have them.Don't use vinylester or polyester.
And wear a mask and latex or rubber gloves when you use the stuff.You should also wear some sort of dust or respirator mask when you cut or sand the carbon rods too.

Real careful with the CF. I used to work in a test lab and we tested samples to qualify aircraft parts. You do not want to get slivers of CF in your hands or worse yet breath the dust in.

[Martijn]

Thanks for your comments! Hm it's a difficult decision though.

The intention if the reinforcement strip is to resists bending and creep. So if the strip fits very precisely in the slot you wouldn't need glue at all I would say. As one of you commented, it would only need glue to keep it from rattling, which I can imagine. But to make sure I don't have to sand the carbon fiber to obtain a flat surface for the fingerboard, I make the slot a bit deeper than the height of the CF.

Here in Holland epoxy is unfortunately not easily available, only some boat-building shops sell it in 1/4 gallon tins, costing about 60 dollar.

[Jim.S]

Originally Posted by Martijn

Thanks for your comments! Hm it's a difficult decision though.

The intention if the reinforcement strip is to resists bending and creep. So if the strip fits very precisely in the slot you wouldn't need glue at all I would say. As one of you commented, it would only need glue to keep it from rattling, which I can imagine. But to make sure I don't have to sand the carbon fiber to obtain a flat surface for the fingerboard, I make the slot a bit deeper than the height of the CF.

Here in Holland epoxy is unfortunately not easily available, only some boat-building shops sell it in 1/4 gallon tins, costing about 60 dollar.

On the neck under tension the stresses are highest at the surface of the wood, fret board surface in compression and neck back in tension. If you put that carbon fibre in the center most of it will be in the neutral axis of the neck (beam) and wont do much there. The CF will reach either side of the neutral axis so I guess provide some stiffening but you will have to glue it in firm to get the most from it. If you don't glue it in you will have no shear strength between the CF and wood so they can just slip past each other. I think you would be best to get the CF as close to the extreme rear of the neck rather than up the middle, that way will produce the largest effect.

Yep that West systems is expensive, looks like about the same price as Australia but it is one amazing bit of epoxy. Are you sure you can't get the 500ml size, that is how I buy it for about $35 from memory.

Jim

[Sanjuro]

I would suggest a polyurethane glue. The bond between the CF and wood will be incredibly strong. A quality 2 part slow set epoxy would be a good choice as well.

[redir]

Originally Posted by Jim.S

On the neck under tension the stresses are highest at the surface of the wood, fret board surface in compression and neck back in tension. If you put that carbon fibre in the center most of it will be in the neutral axis of the neck (beam) and wont do much there. The CF will reach either side of the neutral axis so I guess provide some stiffening but you will have to glue it in firm to get the most from it. If you don't glue it in you will have no shear strength between the CF and wood so they can just slip past each other. I think you would be best to get the CF as close to the extreme rear of the neck rather than up the middle, that way will produce the largest effect.

Yep that West systems is expensive, looks like about the same price as Australia but it is one amazing bit of epoxy. Are you sure you can't get the 500ml size, that is how I buy it for about $35 from memory.

Jim

Yup. I would recommend to the OP that you do a serious search on how tensions in a neck are applied from string tension from an engineering standpoint and then decide for your self if even using CF is worth it in the first place. Because if it is not installed properly, farthest away from the neutral axis, then it's only marginally worth putting in if at all. Intuitively it seems right, I've done it on many guitars I built and have marketed them as such, up until I actually read in detail about it.

There is essentially a zone, a line really, called the neutral axis that represents the equilibrium between compression and tension. In this zone nothing you can do will make any difference. This zone happens to run right down the middle of the neck where your truss rod goes. An adjustable truss rod of course is usable here but not a static one. So you need to either dig real deep the slot in your neck to get as close as possible to the back of the neck shaft (where your thumb goes when playing) or rout into the fretboard and get as close to the fret tangs as possible. IOW move as far away from the axis as possible.

Most people I think would prefer to rout deep into the neck. In that case you would want to epoxy the CF in and then cap it off with a wood filler strip. Epoxy is the preferred glue as it will bond to everything around it. If you use Titebond then you are creating more of a mechanical process to hold the bar in place rather than a chemical one. My guess is that if the fit is tite then it would be ok.

In the US you can get epoxy very easily I'm wondering why it's so hard to get in the Nederlands? Even the 5-minute stuff would do.

[Martijn]

I teach first-year mechanical engineering students in statics and strength of materials, so I am pretty aware of the maths behind it.

Still I think carbon fiber reinforcements could be very useful. For just withstanding string tension the carbon fiber is not needed indeed, millions of guitars have been built with just a normal trussrod.
Although, I wouldn't call the difference just marginally. The height of the carbon fiber is about half the height of the neck thickness (excluding the fingerboard), and given the difference in Youngs modulus between both materials it does make quite a difference.
It's also about creep of the material. Some guitar necks tend to show some kind of S-shape over the years, it's unlikely that will happen to a carbon fiber reinforced neck.
Two strips of carbon fiber placed at a large distance from the neutral axis will make the neck much, much more stiff indeed. But in fact, I would be afraid of using the trussrod during initial setup and finetuning... Stock trussrods are not designed to deform constructions with such high stiffness.

I might have found usable glue, what do you think about this one?
http://www.bison.net/en/products/647...oxy-universal/