Questions about carbon

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Flatliner
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Questions about carbon

#1 Post by Flatliner » Thu May 14, 2015 5:45 pm

I've had request for carbon limbs :? ,,,, Don't know a thing about it, so if those of you that have used carbon could direct me to some threads or share your opinions on things like where best to get it from? Do you use it instead of glass or as a lamination instead of wood? What difference does it make to the draw weight as opposed to timber laminations? Is there any special prep procedure???? :think: You know stuff like that :roll:.

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Rob.
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The Ranger
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Re: Questions about carbon

#2 Post by The Ranger » Thu May 14, 2015 7:15 pm

G'day Rob, I used a piece of carbon in one of my very first bows. I didn't know much about it and was told by Bingham Projects (who I bought it off) to put it directly under the fibreglass on the back of the bow. They also said that it would give the bow an increase of around 5lbs to the overall draw weight.

Other then that, I couldn't see any other benefits to using the carbon. That's not to say there aren't any, I'm just unaware of them if there are.

Hope this helps,

Stuart
Don't practise until you get it right. Practise until you don't get it wrong. Ranger Bows.

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greybeard
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Re: Questions about carbon

#3 Post by greybeard » Fri May 15, 2015 8:42 am

Rob, did the customer mention why they wanted carbon limbs?

From Binghams;Carbon Unidirectional Glass,

A unidirectional carbon laminate limb core lamination that provides the ultimate in light weight strength, stiffness and increased performance by providing the highest response, rate of return, weight reduction and fatigue life available. Sanded 2 sides.

They mention "weight reduction" but it still needs to go under glass.

It would appear that cross weave carbon is the way to go.

Have a read of the following;

http://peteward.com/2014%20reviews/Test ... mb.1..html

Search the internet, there are a lot of opinions out there.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

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Nezwin
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Re: Questions about carbon

#4 Post by Nezwin » Fri May 15, 2015 11:39 am

Seems like everyone is getting interested in Carbon lately... There's a very similar thread to this on a US forum at the moment too.

Placing carbon under glass would make a small change but not significant, the outer 10% of the limb cross section doing most of the work. It does look good, although not traditional.

I am currently intermittently working on my second carbon backed bow, the first effort not being all that great and just thrown together with leftover materials, hence the awful colour matches! In particular, the carbon laminate didn't turn out well but I didn't want to waste the carbon. Shoots well though and Yeoman Dave was very encouraging when he took a look at it a month or so back.
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The imperfections in the carbon laminate are pretty clear here. The next bow will be avoiding this.

68" ntn, 1/8" Carbon & Pretensioned Glass lam backing (parallel), 1/8" processed Bamboo core (0.002 taper) & 1/8" Lemonwood belly (0.001 taper), double recurve. 18" riser is Pink Ironbark with 24" working limb length. Came in at 30# @28", for weight reference.

Bloke in the first shot is not me, so his 4-finger draw is doing weird things with the tiller. And this was a rough, thrown together bow. The next is working out to be much neater.

Carbon can be sourced as cloth from CG Composites in Brisbane but you would be required to buy a 1/2m width by whatever length. It's about $45ish a metre, of fixed 1/2m width cut from a roll. If you want, I could trim some 2" x 2m lengths & send them up. Always happy to help.

Edit: When I lived up the top I bought some epoxy from a company called 'Nuplex' in Cairns. They may stock carbon cloth.
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cmoore
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Re: Questions about carbon

#5 Post by cmoore » Fri May 15, 2015 5:50 pm

:shock: very striking bow nezwin!!! Loving it :clap: got anymore pics of it?
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Re: Questions about carbon

#6 Post by rodlonq » Fri May 15, 2015 7:16 pm

Gday Rob,

I think the idea is to replace 0.050" glass with 0.015" carbon under 0.020" glass, or something like that (with the same core stack). The benefits would be even higher with foam core laminations rather than bamboo as it would give a higher % reduction in weight.

I did a fair bit of reading about it a while back but the price of the materials was too high for my budget. Look forward to seeing what you come up with Rob, I'm sure it will be good.

Cheers... Rod

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Re: Questions about carbon

#7 Post by BowmanBjorn » Fri May 15, 2015 10:11 pm

hi guys,

i haven't had the opportunity to use carbon in a bow but i've used it extensively in manufacturing of performance sporting goods some of which have similar requirements as archery.

carbon weave of different types is widely available in both plain cloth, prepress etc and depending on what your trying to achieve can be woven or unidirectional to suit compression or elongation.

Carbon finer often replaces fibreglass in most situations as it has a higher strength to weight ratio and is significantly more efficient at transferring energy. both of which i would imagine would be useful in the limbs of a bow. you could make a lighter and more efficient energy transfer limb with the same poundage.

when you guys are building bows with fibreglass do you use cloth or do you use pre cured sheet and glue it down?

if using cloth then potentially you could vacuum infuse the resin in the limb form and then cure in a hot box to reduce overall weight as much as possible.

i would assume you would maintain your bamboo limb cores and then replace the fibreglass with carbon finer. i can't see the need for the additional fibreglass over the top, carbon is more than robust enough to take the day to day scratches and bumps of an archer or bow hunter.
Centaur Triple carbon elite 2pce 60# @30"
Thunderstick MOAB 50# @30"
Flat line Raptor 45# @30"
Norseman Wrath 2pce 54# @30"
Norseman trilam ELB 104# @ 32"

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Re: Questions about carbon

#8 Post by rodlonq » Sat May 16, 2015 11:05 am

Hey Rob, Here's a picture I got off google. Cant seem to find who supplies the materials though.

Cheers.... Rod
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Re: Questions about carbon

#9 Post by Flatliner » Sat May 16, 2015 1:37 pm

Thanks Stuart, good info mate. Was the bow you used it in a recurve or longbow? I would imagine it would have more effect on performance in a bow with a smaller over-all core stack.
greybeard wrote:Rob, did the customer mention why they wanted carbon limbs?
Not in so many words Daryl, but I imagine it is simply for the little bit of extra performance. Interesting link thankyou.
I agree that the cross weave would be the way to go even if just for looks, but I'm having trouble tracking down a supplier of solid laminations made with woven fabric, (if they even exist that is).

Thanks for the info Neswin, very nice bow BTW, but I wasn't planning to use cloth (that's a whole other level of confusion), I was hoping to find a solid lam material.

Hey Bjorn, I agree with everything you said but I am not keen on having to work with a cloth material and am having trouble finding a supplier of "pre-cured" strip laminations in woven carbon fabric.

Nice pic Rod, shows the construction very clearly, but finding a supplier :roll: .

And after all that the order has been put on hold for a while so I've got some time to do a little more research

Thanks guys,
Rob.
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Re: Questions about carbon

#10 Post by greybeard » Sat May 16, 2015 3:28 pm

Rob, the following links may give you a starting point.

http://www.colan.com.au/compositereinfo ... brics.html

http://www.carbonfiber.com.au/prod1.htm

Use of carbon fibre composites - OHS information sheet.

http://www.monash.edu.au/ohs/topics/inf ... ibres.html

It may be beneficial to obtain bow efficiency data to see if the limb design needs ‘tweaking’ before delving into carbon.

The following is a reply [2009] from Elmont Bingham regarding their rigid carbon strips.

From: daryl [mailto:greybeard@pcsol.com.au]
Sent: Sunday, February 22, 2009 4:14 AM
To: Bingham Projects Inc.
Subject: Carbon Glass

“Hi Daryl,

Thanks for your questions. Gordon carbon is meant to be a core material backed by glass. It is meant to be one piece placed as far away from the center as possible on the tension (target) side. It will give increased performance and consistency. Now, some customers have put carbon under back and belly glass. This would be for longbows only. It is a disaster with recurves. It changes the weight drastically. You can’t even begin to use our weight chart. I haven’t done this myself but I do have a few customers that have tried it. Some customers have even tried carbon, sanded 1 side, on back and belly with no glass backing. This also changes the weight drastically as compared to the weight chart. I have heard mixed results with this. Some say it’s great, some say they are getting cracking issues. If Gordon carbon is not backed, it is an expensive experiment with no guarantee. This is an issue that has a lot of talk associated with it but no clear answers. It has never taken off.

Sincerely,
Elmont”


Woven cloth would appear to be a better option although it would probably require some form of resilient finishing coat or pre forming it into rigid strips.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Re: Questions about carbon

#11 Post by rodlonq » Sun May 17, 2015 8:10 am

When you're done there Rob, here is some more homework for you. :lol:

http://archery.berkeley.edu/wp-content/ ... e-Bows.pdf

Cheers.... Rod

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Re: Questions about carbon

#12 Post by rodlonq » Sun May 17, 2015 8:29 am

Found one supplier Rob,

http://www.kustomkingarchery.com/Bearpa ... info/4837/

Cheers... Rod

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Re: Questions about carbon

#13 Post by greybeard » Mon May 18, 2015 3:18 pm

Rod, thank you for the link to Fundamentals of the design of Olympic recurve bows.
greybeard wrote:....It may be beneficial to obtain bow efficiency data to see if the limb design needs ‘tweaking’ before delving into carbon......
The following extracts from the document re enforces my earlier reply;

Abstract;

“Also examined is how changing the bow geometry, new materials, and construction techniques can lead to improve bow performance.”

Introduction;

“In order to realize the full potential performance improvement offered by new materials and manufacturing methods, the geometry of the bow must be optimized.”

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Re: Questions about carbon

#14 Post by rodlonq » Mon May 18, 2015 4:24 pm

Quite so Daryl, it leads one to believe that for a given set of parameters (bow length, draw length, draw weight, relative arrow weight and etc.) there can be only one optimal design. It follows that if the design of a particular bow is not the same as the optimal, then it should be??? On the other hand, one bow design may be optimal for one particular archer while another design may be optimal for another archer.

Another factor is, what purpose? A bow optimised for long range target shooting may be a bit delicate for dragging across a muddy swamp on your belly to get a good shot on a boar. Meanwhile the bowhunters rig may be a bit clunky for an Olympic shooter.

However there may be a plethora of designs that are sub-optimal and yet may benefit from improved materials.

My guess is companies that mass produce olympic quality bows probably have spent more $ than I'll ever earn on optimisation of design. For the back yard bowyer, an improvement in their existing sub-optimal design by materials upgrades could be a lot cheaper than design optimisation trials. Ordering some woven carbon strip to add to the next bow may yield as much gain as building and trailing the next 4 forms.

All that being said, there is a certain lure to the challenge to make a better performing bow. It is simply a choice between going hunting or going to the shed and tinkering with bow design :biggrin:

Cheers... Rod

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Re: Questions about carbon

#15 Post by BowmanBjorn » Mon May 18, 2015 7:23 pm

The big thing is that the use of carbon willl yield a lighter limb for a given draw weight and will also release the power faster and more efficiently than glass.

So for a give. Limb shape (optimal or not) carbon will offer a lighter limb, which should lead to greater limb speed and a more efficient release of energy also increasing limb speed. The faster the limb speed the faster the arrow will be shot from the bow.

Ideally a mixture of the best possible limb design to a give. Draw length, draw weight and arrow mass combined with the use of carbon the make the limbs lighter and more efficient t and storing and releasing power will offer the highest performance limb.

The next challenge is sorting through the different types of carbon fiber weave t300, t700, unidirectional ceramic impregnated carbon, thin weave, broad weave. Tapered layer laminates, parallel layers, diagonal layers etc

In traditional archery I think there is a lot of room for improvement. Loos at border limbs, centaur archery triple carbon etc.
Centaur Triple carbon elite 2pce 60# @30"
Thunderstick MOAB 50# @30"
Flat line Raptor 45# @30"
Norseman Wrath 2pce 54# @30"
Norseman trilam ELB 104# @ 32"

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Re: Questions about carbon

#16 Post by greybeard » Tue May 19, 2015 3:16 pm

Rod,

When talking about optimizing limb design I believe target weight bows need different parameters to those of a hunting weight bow.

Two points that come to mind are bow/working limb length and arrow mass.

It would be interesting to know if anyone on this site can quote their bow efficency percentage data.

The following is an interesting read but their longbow descriptions [reflex/deflex/hybrid] leave a lot to be desired.
Defining Bow Performance Dryad.pdf
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Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Re: Questions about carbon

#17 Post by rodlonq » Tue May 19, 2015 9:11 pm

I'll have a look tomorrow, I should be able to calculate the efficiency of my new 3 pc TD recurve design, but only for 10 grn/lb of draw weight. That is the only mass I have velocity data for.

I have often wondered why efficiency is not a more prevalent number given some of the marketing hype you see. I suppose it is sort of implied in IBO speeds for the high tech guys.

Cheers... Rod

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Re: Questions about carbon

#18 Post by greybeard » Wed May 20, 2015 9:10 am

Rod,

Although the newer materials such as carbon and foam may enhance limb performance the current 'run of the mill bows' far exceed my ability as an archer.
rodlonq wrote:......I have often wondered why efficiency is not a more prevalent number given some of the marketing hype you see.......
Maybe because efficiency percentages vary as does arrow velocity when arrow mass is changed. Perhaps it could be confusing in the market place.

From an earlier post;

http://www.ozbow.net/phpBB3/viewtopic.php?f=3&t=14575
longbow steve wrote:
Longy58 wrote:Hello bowyers,

I recently acquired a Barry Johnson Longbow and was wondering if any of you bowyers have used carbon fibre laminations at all in your Hill style bows, and if you have is there a noticeable improvement over what you would normally use.

Regards. Richard.
Hi Richard, you could expect a slight improvement in speed if used without glass on the back through weight reduction and stiffness. Used under glass would be a fairly slight speed gain. I have an American made bow with 2 sets of limbs, one with carbon under glass the others without and there is no noticable difference in speed. The bows I have made with uni carbon and weave over the top have been increased in speed and draw weight over their glass counterparts. Steve
Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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