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I'm thinking about buying some yards of carbon fiber and some epoxy to mess around with and see what I can do. Has anybody ever made/covered anything with carbon fiber before and can provide any tips and tricks? Such as the best epoxy and what to use as the over coating that is durable enough to be on the outside of a motorcycle, what threading pattern looks the best, a good small/cheap vacuum kit?
 

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I'm thinking about buying some yards of carbon fiber and some epoxy to mess around with and see what I can do. Has anybody ever made/covered anything with carbon fiber before and can provide any tips and tricks? Such as the best epoxy and what to use as the over coating that is durable enough to be on the outside of a motorcycle, what threading pattern looks the best, a good small/cheap vacuum kit?
What your asking takes some people many years and a degree to answer. My company makes composite military shelters and Truck bodies. We deal mostly in E-glass but at times use carbon. Let me try to answer.

1. It sounds like you are only trying to use the carbon for aesthetics. If this is true, your resin isn't AS crucial. When you are working with structural parts the carbon/resin compatibility is VERY important. My best recommendation is to speak with you Carbon vendor or your resin vendor. They will tell you what is the best to use.
2. A gel coat is what will be your most durable coating. It is used in the boating and transportation industry. This will require a vacuum bagging kit. Don't be fooled it will not be a cheap kit. You are looking at several hundred dollars for a demo kit. You can make a simple one with a shop vac but your results wont be as good. Also Vacuum bagging is an art. It will take you a long time and a lot of waste to get your resin flows right.
3. As for your threading pattern. This is just something that you will need to control. Just keep all the parts consistent in the thread direction.

My recommendation based on price and design intent is to just do simple reverse mold. Get some cheap fiberglass and make a mold of the part that you wish to make. Then lay up the carbon in this mold. It will give your a smooth finish now on the side that will be exposed. Also you will only have a resin surface exposed. This can be cleaned up to look acceptable but could degrade over time.

Hope this helps.
 

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Never formed any complex shaped parts but I have several years of experience with carbon fiber.

I have made composite tubing for supersonic high stress flight and flat stock for similar purposes, dont ask ;)... long story.

Anyways.

For a motorcycle any laminating resin will work, I use aeropoxy because its very strong stuff but I need it for my purposes. Any laminating resin will be strong enough for a motorcycle non-stress part, you wont be able to break it. Look into West Systems, Aeropoxy, there was another company I used once I liked, US composites I believe?

Anyways you want a laminating resin (I know I said it three times but its important) because anything else wont soak in well enough, you need to be sure it has a decently long curing time (more then an hour or two) as you need time to work with it and if its to short it will thicken up quickly, especially if you make a large batch.

Use something epoxy based, not polyester like bondo.

Mixing is very important, make sure the ratio is close for hardner and resin is pretty accurate and mix for a couple of minutes vigorously, I have found mixing on a flat surface to be ineffective, I mix in a drinking cup (disposible of course) and it works well.

There are all kinds of weaves, they all have different looks but just be sure and get something bi-directional (lots of unidirectional stuff out there these days that obviously wont work and looks horrible), twill weave is interesting, I always stuck with high quality plain weave myself.

On a side note, another thing to look into if you want something really unique is a hybrid cloth.

http://compositeenvisions.com/images/pink carbon fiber fiberglass hybrid.jpg

Half carbon, half fiberglass or kevlar. I'd do glass, easier to cut. Usually you can get the glass colored, very cool look.

Where was I... Do some research on the CF, I have had some stuff that worked fine but it was thick feeling and would be harder to work with on complex shapes. I have also had some rolls that were like soft velvet or silk, could be molded into any form I wanted.

Now for the actual application. If you are adding to a previous layer, make sure that layer is roughed up for good bonding. Apply the mixed epoxy/resin with a brush very lightly, you just want a layer to help the cloth bonb but if its to thick it will float and not bond to the lower layer. Apply the dry cloth and work it in so the thin layer tacks it in place. Now start working with a brush or roller to get the epoxy to soak into the carbon. This is a key point here which makes CF harder then fiber glass. It doesnt change colors when its saturated. Dont over do it, but make sure you work it in there good to fully saturate the cloth.

Add layers as you go, repeating the process.

When it comes to the last layer, have a bit of extra epoxy but not to much, so you have something to sand into for the final finish. If using a vacumm bag you will need to cover in peel ply, or teflon coated products (have found some teflon coated nylon or similar porous release products to work better then peel ply but they all work) and then some thick breather material. Then bag!

I always liked to use mylar, anywhere from .005-.014 (.005 or smaller risks folds and creases) as it basically made the product ready to use, smooth and shiny, but it doesnt work with bags really and only works on my flat and round surfaces I made carbon on.

Other then that a few things to keep in mind, some epoxies, especially if its not especially hot out, take more then a week to fully cure. I have had some tubing made where after 12 hours it was dry to the touch, after 2-3 days I could flex it significantly but after a week I could stand on it and bounce without any sensation of flex. I now use a curing oven which makes it perfect and ready to go from the start but just be ready to set them in a warm atmosphere for a while before sanding and doing other finishing work... Good mixing will also insure that it dries on time without leaving wet spots that never fully cure without excess heat.

Thats about all I could come up with and I think I got enough there for you ;). Well now that I am awake from typing this novel I think Ill go do a ride :p...

Let me know what else I can do for you!
 

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Oh and on finishing, I have found almost nothing compares to a fresh out of a mylar wrap carbon tube unless you REALLY sand on polish it but I have used everything from regular spray can clear coat with UV protection to boat polyurethane and even some wipe on urethane.

Just be sure and scuff it with 220 grit sand paper and clean it REALLY well with a solvent or alcohol before spraying. Give it a few coats, with some drying time in-between but not a full dry and then start sanding, starting lightly with 220 maybe (wet sanding) and work your way up to 600, 800, maybe even 1000. Then use a rubbing compound like Turtle Wax for that final polish and maybe even automotive wax.
 

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+1 on the West System...You can often find it in a marine shop for boat repair. The plungers from the bottles dispense near perfect ratios, but it never hurts to have a scale. You can thin out the epoxy with DENATURED alcohol...NOT Isoprpyl. If this is just a one time experiment or your just looking at making a few small parts, fairly non-load bearing(cosmetic) for one time use...not sure about the quantities anymore, but the West System may be a bit excessive. Regular hobby shop epoxy will also work...they also sell sheets on fiberglass in different weights. Some online hobby shops sell small "hobby size" quantities on carbon fiber. Hobby shops also carry carbon rod and sticks if you need some rigidity between layers.
 

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Discussion Starter #7
I am just interested in doing this for aesthetics. I won't be messing with anything that is needed for structural support.

Some more questions:
Would it be possible to make a cover for my exhaust with carbon fiber? Would there be a specific high-heat tolerance epoxy I would need?
And are there any issues with, or how well does wood work as use for the mold?

there was another company I used once I liked, US composites I believe?
That is the company I was looking at last night. Some of those other cloths look pretty interesting too, especially with the colors.


Thanks for the all the info so far!
 

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Discussion Starter #9
heat discolors carbon fiber. you could back a heat shield with aluminum or something heat reflective.
Thanks for the heads up. I'll have to make a heat shield that catches the air in between it and the exhaust and then make the carbon fiber piece have another gap in between it and the heat shield also catching the air. Think this will keep it cool enough to prevent any discoloration?

The good thing is that the stock exhaust isn't very big at all so with all this additional circumference, you will have to look hard to spot the exhaust ;D Of course this is just all ideas at the moment.
 

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there's a company called roarocket that makes a simple hand pump vacuum kit , i have one and havn't used it yet, it's mainly marketed for making skateboards, i've heard it's not so great if you have resin on the entire outside of your piece,skateboards ae mostly layers of wood with glue between them, the kit squeezes the layers against a piece of foam that you shape to establish the profile of the piece. I've made a few very nice DH speed boards,flat with West Systems and Polyepoxy(really strong) west is good and easier to get,marine stores everywhere.
 

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Hey buddy, if you visit here and post about it, I have lists of the products to use, with pictures etc, which I could post up if you'd like. In your situation I'd probably use a vinylester resin instead of an epoxy. You're learning, so you'll waste a lot, and it's cheaper. It's also more resistant to heat and chemical attacks. You should be able to build a bagging setup for well under a hundred dollars, they're quite simple.

The most important thing you need to learn is how to make a quality mould. If your moulds are crap, then all your parts will be too. There's a number of products that make it easier to do though.

There are numerous heat shields out there surviving just fine.
 
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