Carbon Fiber mold 6

[dipstick]

Tube Construction:
I'm in the process of making a 2.5 inch tube with a gradual 90 degree bend on both ends for the purpose of creating a custom cold air intake for a Miata MX5. This cold air intake has to serve a dual task. One is to reach downward to the air dam and bring in cold air upward to a resevoir blasting across a high flow air filter. This filter takes the cool air to the injection system via the 2.5 inch tube previously described. My problem is that being new to using fiber, I'm accustomed to metal and intended to use aluminum but fiber caught my attention, what should I use for mold material and how can I get the two 90 degree bends and all of this being one piece? Anybody!
Great admirations to those minds in the sky,
Dipstick

 

[pointman]

hello I am also interested in knowing how to do this so could you let me know

 

I also want to know how to do this for intercooler pipes on my car.

 

[chaving]

First you can make yourself a model out of plaster or resin, or evan fabricate it.
Then you use your model to make a fibre mould.
After you have made a fibre mould you can hand lay up your fibre to make your parts.

You will probably find that this part is better made in 2 parts. Before you stick the 2 parts together you can smooth out the inside.

Making it in 2 parts would also make it easier to core.

For a first project not an easy thing to do, maybee better going to an expert with your model.

Good luck

 

[RotoUSA]

if you are looking for inexpensive prototype rotomolded parts in PE made using FRP mold, please email me details on
info@rotousa.com

 

carbon fiber is not suitable for high heat environments a cold air intake would probobly be ok but intercooler pipes would not hold pressurized hot air reliably

 

I am in the carbon fabrication biz and I can tell you that carbon fiber can be used in a high heat enviroment. I use an epoxy especially for high temp applications. Carbon is used successfully in making intake manifolds for top fuel dragsters.As for making tubes I belive that making your mold in two parts will give you the best results.
First make a "buck" by making a model of the intended shape and get it as smooth as possable then lay fiberglass or pour a durable plastic material around your model,making sure you can seperate it into two halves when cured.Pop out your model and you have a mold in which to lay up your Carbon piece.

 

question... why would you want to make anything out of composite materials that is doing any heat transfering of any kind??? does carbon fiber have a higher heat transfer rate than aluminum??? i dont think so but im not sure on that.... using aluminum will cool off the air much quicker im sure.... and cool air is a good thing when it comes to engines...

 

because it looks really neat! besides most of us are using enormous intercoolers, way bigger than the application calls for. The air should be plenty cool before even entering the carbon pipe.. I was thinking of wraping radiator hose with carbon fiber, then just rip it out, if enough release film is used the flexible hose should pop out with little effort.. Of course this limits how much wraping you can do around the layup. Wraping the layup in tape makes it stronger and ligher, and smoother. but would crush the hose and cause problems..

Anyone done this yet???
email me at wildman@xwindow.ath.cx with any info you may have.

 

[SammymatiK]

Ok so you say to use a two piece mold but to smooth out the inside before it is put together.... Meaning: lay up the material in both halves let it cure, sand it smooth, then use resin to mate two halves together?

Thanks for the help

 

[fsaeguy]

One Piece Mold!! I am currently working on making an intake piece for a formula sae car using carbon fiber. Our mold has about an 80 degree bend in it and we are using a one piece mold. There is a product called Aquacore that makes this feasible. It is a pretty sweet material. You can find their website on google. It is a water soluble material that you can pack into a starter mold in roughly the right shape. All you have to do is bake it for a couple hours around 100F then shape it exactly with a file. It dries real hard and you can completely inclose it. Just drill a small hole after layup to wash out all the mold material with water. You can layup on top of it using their Aquaseal, but we have had trouble with the Aquaseal sticking to the mold. I would stay away from the seal if you want a nice finish. Just lay it up as you would normally using dry or wet layup (dry has a much better finish look). We use ABS plastic in roughly the right shape as the "starter" mold. The Aquacore is about a hundred bucks and you have to buy a five gallon bucket minimum, but its worth it because it usually takes a couple tries to get the right result. Hope this helps.

 

[TomH]

This thread is almost 2 years old, but people keep it alive, so here's a little more help on building tubes. You can use Aquacore (see previous post) to make the prototype core, or you can try to find a soft, flexible foam tubing to use as a core. Think swimming pool toys like noodles, or foam pipe insulation. Use a bendable metal spline (aluminum rod, coathanger wire, etc.) down the middle to form the bends. You're going to make this flexible core, form the carbon fiber (CF) laminate around it, let it cure, and then pull the flexible core out and throw it away. Epoxy resin does not attack most foams, but test first.

CF does not have to be vacuum-bagged after wetting it with resin, but you can achieve a lighter, more attractive part by wrapping the wet laminate with heat-shrink tape. Here's a site with tube making instructions, and some good epoxy information:

http://www.info-central.org/construction_heattape.shtml

 

[MikeHalloran]

The OP has probably already figured out these two things, which I post for others' benefit:

An easy way to make an odd shaped tube is to build a core in the shape of the interior, entirely from paraffin wax, wrap the wet laminate over that, and wrap the whole assembly in Saran Wrap to debulk it. When the Saran is easy to peel off, the resin has cured.

Directing air from in front of a chin spoiler/ air dam into the engine also directs water from deep puddles into the engine. Several bent connecting rods detract seriously from the resale value of a Corvette.

-Mike-

 

[davidinindy]

"Several bent connecting rods detract seriously from the resale value of a Corvette."
Yes, but he's working on a Mazda MX5... P-)

 

[patprimmer]

If we want to be picky about details, he WAS working on an MX5, about 3 YEARS AGO.

The original post is very ancient history, so come on guys, play nice.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Jtultra]

Hi, um.....I'm gonna bring the forum back to life. I have a 200 Toyota celica GT-S. My current intake is a hybrid between Home depot parts and the original intake. My current design around 25% better than anything else in the market. I'm looking to make a complete carbon fiber tube or the life w/ a much straighter design, I believe about one 80 turn and one 30 degree(estimates).

From what I have gathered, my best and cheapest route would be to making a foam core from swimming noodles, and wrap that in CF. the question is.....

how many layers of CF do I need to apply?

I'm using west systems epoxy is that sufficient?

how will I be able to to release the foam core?

I have some PVA, Peel ply, and silicone spray, How should I utilize those releasing agents?

I have problems w/ bubbles in my epoxy, how should I deal w/ that problem?

i think vacuum bagging will bring out the best product, can I use a conventional vacuum, with a filter to catch the epoxy, and by wrapping the pipe with peelply?

I was also thinking of going to a muffler shop and have them bend me a tube to my specs, Then wrapping it w/ CF to achieve the look, is that feasible?

***Thats all I believe, I'm only 18 years old and I'm eager to learn more about fabrication. Hope one day to be able to produce this tube in quantities and resell them to make a profit, with as low of cost as possible

any help will be greatly appreciated

 

[patprimmer]

If you use polystyrene foam, once the epoxy has set, you can dissolve the styrene out with paint thinners.

If you use exhaust tubing, you will not be able to remove it from the moulding, unless you split the moulding then glue the 2 halves together, a process I would not recommend for reasons of both strength and aesthetics.

I am sure that West Systems are good epoxies, and you need to work the air bubbles out with a roller or pressure, by say,wrapping with plastic film layered on in a similar manner to applying a bandage.

The easiest way might be to buy some carbon fibre prepreg, then wrap a styrene foam core, then cure the prepeg, then dissolve out the core. You would need to verify that the curing temp was below the deflection temperature of the core.



Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Jtultra]

how about vacuum bagging?

 

[patprimmer]

I doubt you can pull enough vacuum with a domestic vacuum cleaner.

Even if you do, you risk drawing some resin over and ruining the machine.

Wrapping tightly with plastic film will expel the air. The cure temperature and the strength of the wrap and the mould at those temps will be the main concern

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[ArffinIsht]

Hi
I need advice on super smooth CF asthitic surface finishes.

Im attempting a complex shape specifically for load bearing therefor the former need not be removed but it also needs to look dam sexy so bandage style wrapping is out.
I need a way to have sheet CF finish without joins you know the ones where you cant see the fiber edges under the resin(like the proshow is that acheived?

It feels like i should laquer the inside of a one piece mould and somehow feed in sheet CF in in perfect cut shapes then inflate a thick baloon inside to form it but thats dum...is it?