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Laying carbon for protector.

Carraig042

me 1st
Apr 5, 2011
472
75
East Tennessee
If anyone has experience with laying carbon, I would like your input. I have made things from fiberglass in the past, but fiberglass obviously would not be strong enough as a downtube protector. I am wondering if polyester resin will work for this application or if i really need to use an expensive epoxy resin?

And should I use aramid (Kevlar) instead of carbon since it is less likely to shatter?

-Brett
 
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HardtailHack

used an iron once
Jan 20, 2009
2,403
287
Fibreglass would be fine you just need a resin that will flexible instead of over building the crap outta it-
Crap vid but you get the idea-

 

fireman

Monkey
Jan 28, 2004
144
0
Boulder, CO
I would agree fiberglass is probably fine.

Carbon fiber and fiberglass can have around the same strength, there are of course many varieties and some carbon fibers are much stronger but in general... The big difference is stiffness, a carbon/epoxy composite might be 3-4x as stiff as a fiberglass/epoxy composite (again there are some incredibly stiff carbon fibers that would be much more, but they are also very expensive and not as strong).

Kevlar is in the same strength range (though it isn't at all good in compression) and is in between carbon and glass in stiffness (closer to glass). My experience was that working with Kevlar sucks, though maybe if you are willing to spring for some proper scissors/cutting tool it wouldn't be so bad.

For a DT guard stiffness isn't that important, strength is what you really need.

As for the resin if you have polyester around I'd probably just use it, but if you are going out and buying it I would get epoxy as it isn't going to be that expensive for the small amount you are going to need.
 

Carraig042

me 1st
Apr 5, 2011
472
75
East Tennessee
I think I would use the carbon fiber over the fiber glass with part due to appearance. The material is not too expensive. I was looking at the prices for the Epoxy resin with hardener looks to be around $50 unless someone can point out some cheaper.

-Brett
 

w00dy

In heaven there is no beer
Jun 18, 2004
3,413
30
that's why we drink it here
The lay-up process is about the same for all. Kevlar is a pain to cut, but it's much better in abrasion resistance. If you have the means I would do a layer of Kevlar on the exposed face and something stiffer underneath. Vacuum bag it to remove the extra bonding agent. That has more to do with the weight than the fiber material.

Make sure to wear gloves working with glass or carbon. The small particles of that sh!t are awful.
 

Carraig042

me 1st
Apr 5, 2011
472
75
East Tennessee
No kidding. I used to work a summer job at a body shop. None of us wanted to do the fiberglass work becaue it made you itch like crazy all dang day.

what do yu guys think about the Carbon/kevlar woven together fabrics? Would I get the best of both worlds? I saw Solar composites has a small size of that stuff for a good price.

-Brett