Carbon Unidirectional Glass?

[greybeard]

Have any bowyers on this site used Carbon Unidirectional Glass?

The following is from the Bingham's catalogue.

“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. Recommended for laminated limbs with Bo-Tuff E Glass being used as skin glass. Results from the use of this glass may vary depending on the limb weight and design. Available in Natural (blackish-gray). Sanded 2 sides."

I am hoping that someone may be able to qualify or quantify the advantages of using a carbon fibre laminate under the backing glass. To keep the question in context I am referring to the general target/hunting flatbow or recurve scenario, not Olympic Games standard archery.

Depending on product specification, postage etc a 72" length could set you back in excess of $60-00 landed in Australia. Ordered in conjunction with other products may help to defray the shipping costs.

Daryl.

[danceswithdingoes]

It aids in faster limb recovery Darryl and thus better cast.....but is it 'traditional'?

[longbowinfected]

Ding,
I'll bite the lure..

Just call me "trout"

What is traditional about CNC macined brass or stainless points, areldite two part epoxy glues, fibreglass, plastic nocks, most string materials, alloy or carbon arrows?

Isn't timber under pressure and heat really carbon just like burnt timber, cellulose or sugar?

Kevin

[longbow steve]

Hi Daryl, The gains are mainly from weight reduction, the carbon seems to be 15-20% stiffer than glass so less material is used in the limb.
The done thing is to grind the glass to .010" and use that as a protective skin but some do use it without glass ie Martin Viper bows.
I have used it once successfully as a backing but the bow was a failure for another reason . It did however give me the above stiffness data. Steve

[GrahameA]

Morning All.

The Modulus for Carbon is better however, in my opinion, the question is more along these lines.

I am hoping that someone may be able to qualify or quantify the advantages of using a carbon fibre laminate under the backing glass.

It should result in a lighter limb with a faster recovery rate. However, just how much better is it over glass?

Whilst I am tempted by it I, for one, an wondering if I could get an equivalent performance increase by optimising a bit more the design of the bows that I build. Or is there a siginificant jump in performance by the use of carbon laminates?

So for a given bow design how much of performance increase can one expect by the replacement/addition of the glass by carbon fibre? Has anyone built two bows the same and then done the comparison?

p.s
Steve.

The done thing is to grind the glass to .010"

Thanks for that - I was actually thinking if that was a possibilty.

[longbow steve]

Hi Grahame, I believe it is a good idea to optimise your design first with regards to taper of core, length, core material before adding the expense of carbon. Then you may gain 3-5 fps with a backing of carbon, do the belly aswell and you gain that again.
If I had the time I would tiller the carbon bow and compare as it is identical to another I have. Steve

[greybeard]

It aids in faster limb recovery Darryl and thus better cast.....but is it 'traditional'?

Ding,

The post is in 'Shooting the Breeze' and not 'Traditional Tackle.'

Daryl.

[greybeard]

Hi Steve,

Thank you for the information.

Daryl.

[Chase N. Nocks]

It's always traditional to improve things

And Daryl, I'd be perfectly happy to use one of your bows in the Olympics.

Unfortunatley my silly comments don't help your technical question...Steve's reply about thinning the glass was interesting.

[GrahameA]

Hi Steve

Hi Grahame, I believe it is a good idea to optimise your design first with regards to taper of core, length, core material before adding the expense of carbon. Then you may gain 3-5 fps with a backing of carbon, do the belly aswell and you gain that again.
If I had the time I would tiller the carbon bow and compare as it is identical to another I have. Steve

I know that bows I build are not optimised. I make them longer than necessary as I prefer them that way and I want to stay away from the stack regime.

If I was to optimise the design a bit I could probably gain 5 fps on average.

I will have to play around with a bit of design work at some stage.

Thanks for your comments they are appreciated.

[Stickbow Hunter]

The done thing is to grind the glass to .010" and use that as a protective skin

Steve, I couldn't imagine me ever doing that as I honestly don't think the glass is tough enough at that thickness to take everyday bumps and knocks which is par for the course when out hunting. Obviously the glass would have no scrim in it which would also make it more vunerable. I also think there would be a very high risk of the glass splitting length wise just handling it and glueing it up and amking the bow etc. I can't see the benefits in gaining a few feet per second at the loss of reliability.

If one was going to use carbon I think it would be better to use one of the types of carbon meant to be used for the back and belly of bows rather than the Gordon's product which is not. Where you get such a product is another question though.

Jeff

[greybeard]

The done thing is to grind the glass to .010" and use that as a protective skin

Steve, I couldn't imagine me ever doing that as I honestly don't think the glass is tough enough at that thickness to take everyday bumps and knocks which is par for the course when out hunting. Obviously the glass would have no scrim in it which would also make it more vunerable. I also think there would be a very high risk of the glass splitting length wise just handling it and glueing it up and amking the bow etc. I can't see the benefits in gaining a few feet per second at the loss of reliability.
Jeff

I can't see the benefits in gaining a few feet per second at the loss of reliability.
Jeff

Jeff, thank you for your input. Your thoughts on the issue are very similar to mine, but I needed to ask the question.

Gaining a few feet per second in bow design means nothing if the archer does not have perfect form. Results from cronograph tests that I have carried out illustrated that inconsistent form can rob the archer up to twenty feet per second in performance.

Daryl.

[longbow steve]

Hi jeff, You are correct the scrim is gone after .020" , I dont know whether the glass will then become susceptible to cracking or whether it is just used as a protective film over the carbon and the carbon takes the load. I mentioned earlier the Martin bow that has the Uni carbon as a back with nothing on it and I believe Predator carbon bows use Uni Carbon and simply have a paint finish on them.
When I find the time I will make a bow with a Uni carbon only back and shoot it till it fails or proves to me it can hold together.
With regards to speed Daryl I find I have to slow my D/R bows up to shoot well with them but in terms of casting a heavier arrow there are numerous +'s
Steve

[Stickbow Hunter]

Daryl,

While I have not seen a loss of twenty fps poor form certainly can rob archers of a lot of arrow speed and give incosistant accuracy; probably a lot more than some realize.

Steve,

I have used both UL and ULS glass and any glass without scrim would IMO be very susceptable to damage especially being so thin. A small nick could/would run (splinter) very easily as there is no scrim to help hold the fibres together. The glass may be a protective film over the carbon but it is the backing, not the carbon. It will be interesting to hear your findings when you build a bow using just the Gordon's carbon for backing.

Jeff

[hutcho]

I believe that our fear to use carbon on the belly and back of bows comes from poor experiences in the early days of carbon fibre application.

For a worthy number of years (in the sense of time to assess failures) carbon has been used in road cycles and for what I consider a long enough time in mountain bikes. Last year a carbon fibre frame was used in downhill mountain biking at the world cup level. for over 10 years I have shot carbon arrows into all sorts of stuff, some of it has even been targets...

The point of this waffle.

20 or 30 years ago the thought of using fibreglass was taboo.

Today fibreglass is a staple in bows.

Carbon has significantly higher properties in compression and expansion than fibreglass, yet as a global community we have the attitude that carbon is bad, it can't handle being compressed, carbon can't handle impacts or knocks, carbon is the main avenue for Osama Gone missin.

Pick your excuse, but I reckon that in 10 years carbon trad bows will be the norm, they are in wheelie bows limbs (which get hauled through the same brush) they are in olympic archery limbs so the needed level of consistency is there.

I am happy to embrace carbon fibre. The use off and best practice in construction has a learning curve that I am happy to be a part of.

[greybeard]

Hutcho, thank you for your reply.

Part of my original post was;

"Have any bowyers on this site used Carbon Unidirectional Glass?
I am hoping that someone may be able to qualify or quantify the advantages of using a carbon fibre laminate under the backing glass."

As Sol said 'oils ain't oils' so at best guess 'carbons ain't carbons'.

Pick your excuse, but I reckon that in 10 years carbon trad bows will be the norm.

Nowhere in my post did I mention 'trad bows'.

Daryl.

[GrahameA]

Morning.

I believe that our fear to use carbon on the belly and back of bows comes from poor experiences in the early days of carbon fibre application.

Speaking for myself, I have no issues with using Carbon (High Modulus Graphite) or other exotics laminates other than the the cost - there is a substantial price jump - and a lack of building experience with them.

...yet as a global community we have the attitude that carbon is bad, it can't handle being compressed, carbon can't handle impacts or knocks, ...

The two major suppliers of Carbon laminates for Bow use in Australia both recommend the use of Glass skins.

... but I reckon that in 10 years carbon trad bows will be the norm ....

Not in the DIY/"Small production" market unless the price differential drops significantly.

There are all sort of alternative materials out there, foam limb core material, ceramic limb core material, Balsa laminates, Boron fibres, etc. However, we do not generally use them not because they may not be suitable rather it is because of cost or availability or there is little information on their use or....

It is not a lack of desire rather the practicalities of use that preclude them.