What are the various types of carbon used in limbs?

[TexasStick81]

I'm trying to educate myself about the use of carbon in a limb design before ordering a new bow.  Some of the information may be beyond me but I would like to know more about the various types of carbon used.  I've read in numerous threads about placement and some acknowledgement about there being differ types but I couldn't find any specifics comparing the types.  Could someone explain what the options for Caron are and maybe some general positives and negatives for each?  I recently spoke to a bowyer who says he's now using an aeronautical carbon and is very pleased with it.  A quick search pulled up nothing on aeronautical carbon, anyone familiar with it and it's use as a limb core?

Thanks,

Zane

[Pheonixarcher]

I am an expert by no means, so take this for what it's worth. The biggest advantage of using carbon in limb cores is its strength to weight ratio. The lighter the limb itself is, the faster it can accelerate and return to brace with less ossilation.  But I am sure there are many other factors involved.  As far as the aerospace carbon, I would assume it has something to do with the ease of use and workability of the material.  Check out the A & H website. They offer a pretty good explanation on limb design. I hope others will post aswell, as I am also interested in hearing their opinions.

[Sixby]

Aero Carb is carbon developed specificaly for use in the Aeronautic industry. Depending on the usage it may be either a matrix or a uni carbon.
the assumption would be that because of the usage of it in the Aero industry that it would be of a higher spec than generic carbon . Quality control and density ect would be better.
Once a bowyer uses a lot of carbon of different types we generally learn by our experience which type of carbon., how much and where to use it in the limb for best limb life and for best usage performance wise;
Of course this knowledge varies from bowyer to boyer and hense so many different opinions./

I do and love to share what I know with other bowers that also share their experience with me. It savea a lot of cost in development and r@d time. We also can afford together to buy larger and work out what we want for individual design in carbon layups.
Generally these designs are top secret and absolutely under wraps from the individual carbon manufactures.
This leads to a great degree of difference in the quality of product and longevity of the product.
My experience is that a lot of people using carbon don't have a clue as to what they are doing but that those that do have are extremely knowledgable and produce a great product/.
My advice would be for you to read the customer reports on various bows and bowyers that build with carbon .

God bless you and good luck, Steve

[TexasStick81]

Thanks Steve.  From reading previous posts on carbon cores I was hoping you'd chime in.  I have shot the exact same bow of his with carbon and with boo twice now and, while subjective, I feel I notice the difference at the same specs.  Not a tremendous upgrade fee either.

[Bowwild]

Straight from the President of Gordon Composites.  

If using carbon, a recommended strategy is to  use a matrix or cross weave on the back and a uni-directional fiber on the face (belly). I don't know why but that's the advice I was given.  I know a lot of bowyers already know this.

[7 Lakes]

I've done quite a bit of research on carbon and by far the best use is a substitute for glass on the back of the bow.  You get rid of the heavy glass and substitute it with a light weight material that's almost perfect for limbs.  

Carbon on the belly often resulted in crushed / broken wood in the fades. It just doesn't take compression.

I no longer use carbon inside the stack, only as a backing.

[amar911]

Mike,

I think your experience with carbon backing being desirable and carbon on the belly leading to potential compression problems is common among bowyers. I personally like exotic wood veneers, and carbon backing covered by veneers that are then covered with half thickness clear fiberglass is a good option for aesthetic beauty. I know the exposed carbon on the back is a more efficient system, but just doesn't look as good to me, although I do have that on one of my bows, and it looks fine (but techie).

Allan

[Brandywine]

Hello:
Here's what three very respected sponsors have shared with me about the "quality" of carbon:

Each has had problems with carbon from vendors being out of specification or being incorrectly layered, if layered at all.  In one instance the source was a vendor supplying passenger aviation!

Carbon works, but each bowyers went through a lengthy process involving trial-and-error to developed a reliable lay up.

No custom bowyer they know of uses enough carbon to force vendors to adhere to uniform quality control.  In one case, supposedly good carbon was so flawed that a large amount could only be used for non-archery ornamentation on skateboards.  This junk did not find its way into their bows.

Each of these highly respected bowyers was totally candid about vendor issues that have embarrassed them.  Each has an impeccable warranty reputation.  I purchase from them with no hesitation and two warranty issues related to the above referenced vendor issues were handled wonderfully.

As one said: When you're on the cutting edge, it takes lots of bows being used to their technical limits to really know which materials and engineering work.

I love carbon, but stopped trying to learn the technical specifics and now am much happier trusting the bowyers.  Our sponsors are great and deserve our respect.

Regards,
Kevin

[TexasStick81]

Thanks guys.  I appreciate the feedback.  

Kevin,  when you said there were two warranty issues what were they?  Was there a noticible impact on performance?  In other words, how did you know that something was subpar in the carbon?  

Given that this is such a new concept, are there concerns about the carbon's longevity in the bow?

[Brandywine]

Hello, Texan:

One involved carbon layer separations in limb butts, later traced to faulty resin.  The other involved a highly trusted supplier omitting a bias layer of carbon that caused limb twist.

There was no way for either bowyer to know!  

Regards.

[TexasStick81]

Thanks Kevin.  I guess my concern is that I wouldn't know how to notice the issue, what tipped you off that there was a problem?

[Peckerwood]

There is one bow manufacturer that makes it's own carbon layup to insure quality control. They have been using carbon on the back and belly of limbs for years with success.

[Sixby]

Oh to have my own carbon factory. Nottttttttttttttttttt! I barely got time to build the bows much less start manufacturing carbon LOL.I would be willing to bet that they do not use pure carbon on the belly of a limb. But I did see a thread and a pic of a certain builder that says that they make their own carbon with a delaminated limb that was delaminated right at the ends of the fades and had cross weave carbon on the belly of the limb. That was just last year. The owner was not a happy camper because he was told it was his fault for some reason./

One reason for the cost of carbon limbs is the liability and expense that people that honor their warrantys obligate themselves for. This is also bolsterd by the r and d time and money involved in building a product the you can offer to the public in good faith.
God bless you all, Steve

[**DONOTDELETE**]

Without going into a bunch of detail here, there real isn't a "Vendor" per say that supplies a consistently high grade "Bow quality" bias weave carbon.....

Most bowyer's work with an aerospace carbon manufactures and come up with his own lay up. He either has the company lay up a matrix consisting of different weaves and lay up configurations along with layers of uni-directional, or he builds the matrix in house. Each different recipe requires extensive testing for strength and durability..... and the stuff costs a bloody fortune.


Brandywine nailed it pretty good..... just about the time you get the perfect combo figured out. Your next batch of carbon comes out with different properties.... it drives you nuts sometimes.

 

Originally posted by Bowwild:
Straight from the President of Gordon Composites.  

If using carbon, a recommended strategy is to  use a matrix or cross weave on the back and a uni-directional fiber on the face (belly). I don't know why but that's the advice I was given.  I know a lot of bowyers already know this.

This quote from Gordon glass is spot on, but not all inclusive..... here's the deal.... A matrix layup using bias and uni carbon can give you the best of both worlds.  The bias weave adds incredible torsional stability to a recurve limb, and even a radical R/D long bow if it's used correctly.  the uni- carbon adds tremendous strength with ultra light weight properties.... BUT... uni carbon doesn't provide any lateral or torsional strength at all, and putting it directly on the belly of the limb is dicey.....fiberglass has better lateral specs for twist prevention than uni does.

Why most all the bowyer's are so secretive of their recipes is that it takes a perfect combination of bias, uni, and glass to get max performance, stability, and longevity....And that recipe changes with every limb design. The cores used, length and location of the working limb, taper rates, and maximum draw length restrictions all come into play too.

[LYONEL]

I have Kirk currently  making me a triple  Carbon Sasquatch takedown & like amar911 I much prefer the look of nice veneers to carbon & as such Kirk will have very thin veneers & glass on the back & belly , I know this won't perform quite as good as just carbon but I love pretty wood (My first bow with Carbon) I plan on sharing my experiences with this bow & can't wait.

[Brandywine]

Hello, Texas:
I saw the separations when small globs of resin oozed onto the sides of the butts.  The twist issue was so faint that the bowyer found it on another bow and began calling his customers for their observations.  

It's reassuring to experience that level of conscientiousness.

Again, for me at least, I've learned to trust established mom & pop artisans AND TO ACCEPT that we raise the odds of having failures when we push the envelope, especially for that extra few feet of velocity. The self-admitted failure rate for these excellent bowyers is maybe one or two bows a year out of a few hundred.  That's exceptional when the issue of faulty materials can arise.

Regards,
Kevin

[Sixby]

That pretty much says it all. If there is a bowyer that actually lays up and makes his own carbon He still would have the same problems that the pros have. He would have resins that came to him differently, carbon fibers not properly made ect. If it were possible to do this with no varience then the pros would do it. They do the best that they can and as bowyers we have to deal with that. When you get a new batch of carbon it may look and mic out fantastic and you will think it is the cats meow . Then you build a bow and test it and it delaminates./ You find out that this batch of carbon has carbon that requires different temp cure rates or some such thing and that one layer did not cure properly. Generally the carbon supplier replaces it as you have a very considerable investment in an un useable product but in the meantime you have lost a bow. veneers, glass cores , your time ect. Again why bowyers do not just throw out all the info. For one they paid a big price to get that info and for another thing if the person wanting the info does not have the personal experience to use it its just a waste of time putting it out there.

Lyonel, I would be willing to bet you will love your bow.

X2 on everything Kirk said.

God bless you all, Steve