Fiber Glass/Kevlar/CarbonFiber Question

[jaymay023]

Hey all, I've got a question in regards to casting props with fiberglass or kevlar/carbon fiber. I'll be casting some War Machine and Iron Man helmets this weekend and was thinking of trying out kevlar or carbon fiber.

I've noticed a majority of the pieces I see here on the RPF are done with either glass mat or cloth. Are there any benefits to using kevlar or carbon fiber over fiberglass? I know the price of kevlar/carbon fiber is higher then fiberglass and it would seem that kevlar/carbon fiber would be stronger. Are there any down sides to using kevlar/carbon fiber? Does it crack easier, or is one more resistant to dings and such?

Thanks,

-Jay

 

[cheech9898]

I would say unless your really good at composite hand-layups, you'll see a minimal strength gain unless you are vacuum bagging also simply due to fiber/resin ratio. Depending on the piece you may see a weight savings. It would be more for the look if the cloth was going to be exposed (ie scratching the paint for battle damage) or just the wow factor of being able to say it is carbon fiber or kevlar. Keep in mind you may have to buy some special shears for cutting kevlar & possibly the carbon fiber too if it has any kevlar tracers in it (the CF the local aircraft place caries near me usually has the kevlar tracers)

 

[LizardJedi]

IMO there really isn't a point to it... CF and Kevlar are much more expensive than regular fiberglass, and you don't really need the extra tensile strength (besides, unless you really know what you are doing, there probably wont be that much of a difference in strength.) Its also a bit harder to work with.

 

[propologist]

are you going into battle or making a prop ?

 

[jaymay023]

I'm making a prop, but having something more light weight would be nice as a wearable piece. But as Cheech mentioned it would also be a wow factor of saying that its CF/Kevlar and for something like War Machine Armor a little more realistic (minus the metal parts). I'm also not really concerned about lining up the fiber ends, as the piece will be painted and if I do make a battle damaged version it be cool to have little bits of CF or Kevlar showing.

I did a little research on the web and some say that there is a 25% weight savings on doing a vacuum bagging process with CF/ Kevlar (so a 4 lb prop would end up being about 3 lbs), I'm Guessing that you would get the same if you used the vacuum process on fiberglass.

I've played with kevlar before years ago when I had a VW Karmann Ghia convertible, the floor boards were rusted out in some places and ended up using kevlar and resin to strengthen up the body and seal/weather proof the floor boards. We always joked that if you got into a gun fight you could flip the car on its side and hide behind it..

Anyways now that I've looked into vacuum bagging, I might just do it for the smoother apperence on the inside of the helmet/armor as well as the compression of the resin and glass to make the piece stronger. Although most of the bagging processes I see involve flat parts and not the inside of a helmet.

Thanks

-Jay

 

[Gilmortar]

with Carbon Fiber, you will need to have your mold made into aluminum diecast mold with an inflateable balloon to go inside it...that is because you have to pressure cast these so NO airbubbles are in CF. They will greatly reduce the strength and dexterity of the CF. It's a very costly and intricate process, not your normal, dip some matting in resin and slap it inside a mold.

 

[SpyderDan]

I've worked with fiberglass and carbon and carbon/Kevlar for auto body work a fair bit over the years.

The carbon materials are considerably more expensive, and harder to work with. Outside of using pre-preg dry carbon materials and a vacuum chamber, the only reason you will see any significant weight savings is that you can go thinner with the carbon and still keep it as strong.

That said, you can lay up wet carbon/Kevlar just like you would with fiberglass mat, and get a very durable product. I've made carbon/Kevlar body pieces specifically for testing durability, and we were amazed at how much abuse it could take.

One area where carbon can significantly outperform fiberglass is in shrinkage, though. Maybe this is actually the better reason to consider carbon when it comes to prop work.

 

[exoray]

Vacuum bagging gets expensive real quick for the small guy, as does carbon fiber and kevlar...

In the end I think it's WAY overkill for 99% of all things in this hobby... With good fiber glassing technique you can do just fine with traditional mats and fabrics...

 

[kell]

are you going into battle or making a prop ?

could not resist...

http://www.therpf.com/showthread.php?t=57960&highlight=advanced+action+suit


:lol

 

[Delmustator]

I've been trying to get someone to make some bladder molds for me to build some CF bike components. Trust me, you better have some serious $$$ in you wallet when you start talking to shops that can do this. A bladder mold can run $5k each (if not more). Everything else is cheap by comparison... :confused

 

[jaymay023]

Ya that Action Suit thread was a good (but long) funny read.

So CF done right is defenitly out of the question (at least price wise). Kevlars a little cheaper then CF and I might go to that after I finish off the first fiberglass suit.

I've done some Fiberglass and kevlar repair work on boats and cars before, but haven't applied this to prop making or even tried using a vacuum bagging system. I'm assuming using the Vacuum bag method would make even fibreglass a little stronger then non-vacuumed?


-Jay

 

[propologist]

could not resist...

http://www.therpf.com/showthread.php?t=57960&highlight=advanced+action+suit


:lol

LMAO...point Kell