amongmany

I'm interested in dabbling in carbon fiber work and I'm curious if anyone has done anything like this and might be able to offer some insights? Any good books? Any websites or suppliers that you're recommend? etc...

Thanks!

amongmany

Otter

Some things I have learned:

- Experiment first with fiberglass -- it is cheaper.
- Don't skimp on the the mold. An ounce of prevention is worth a pound of cure
- It all changed for me when I started vaccum bagging. It is **so** much easier to get rid of bubbles
- I found it hard to do without all the layers in the vaccum bagging process. Read a fiberglass book, it is common practice.
- Epoxy dries **much** faster at 150 F than room temperature
- Don't skimp on mold release. It is sad to see a mold consume itself because you could spent another minute with the mold release.
- Get a fiberglass book. There are many. a good glass person can do carbon - it's not terribly different. I found this one useful, but it is one of many.
http://www.amazon.com/exec/obidos/tg/detai...=books&n=507846
- Experiment a lot. See the first point.
- I like West System epoxy. There are other good brands, too.
- Buy the pump nozzles (like you see on katsup at fairs) for your epoxy cans. It makes it much easier to mix epoxy quickly and accurately.
- Go to the drug store and get a couple of boxes of latex gloves and small paper cups. Epoxy supposedy can have an aquired alergic reaction. Don't be the one to prove it. It's a mess, anyway.
- Since it is a mess, get some thick plasic sheet from the hardware store and cover your workbench.
- Go buy some new high quality fabric shears to cut the fabric and buy the sharpener, too. You can go more exotic, but Fiskars work. If you ever do Kevlar, just buy the Kevlar scissors.
- I used Aircraft Spruce a lot, but they aren't the only ones. http://www.aircraftspruce.com/ntoc.php?sec=cm
- Meet people who make things that go in the water. Surf board makers and boat makers will forget more about glass than you will ever know.
- Check out your local marine supply store.
- The epoxy is weak, the carbon is strong, but neither is useful without the other. That's why you vaccum bag - you use the least epoxy and most carbon possible.
- Air bubbles are the devil in your composite. Get rid of them.

It shocked people, but I used a shop vac and an old gas oven with just the pilot light as an autoclave (if you can call it that). Assuming you don't want to cook your parts in your oven, a plywood box with a light bulb in it isn't bad for an oven.

I have always wanted to try pre preg. Never did, though.

Hope this helps

amongmany

Thanks otter, very helpful insights!

Can you tell me more about what you've built? How difficult is vac-bagging? What do you have to do to get the nice polished finish that we see professionally?

alexf20c

I once super-glued my index finger to my forehead.

amongmany

Why do you bother to waste people's time with this useless crap?

alexf20c

Because I like to piss people off over such trivial nuisances.

amongmany

Enjoy my ignore list.

alexf20c

because I know you just hovered over that link. Honestly, some people need to lighten up.

Otter

I did a bunch of parts for a little racing team. Mostly small body work, some light structural stuff. Also some random hobby stuff that would fall into the same category.

The shape and finish you get is all about your mold. That's it. Well, not really, but it is close.

If you want a mirror finish on your part, you need a mirror finish on your mold. Bondo is popular, as is filling paint. Just expect lots of sanding. A mold is three parts from this perspective.

1. Structure - this gives the shape and holds things together while drying and vacuum, if used. This can be anything from steel to carbon to sticks and twigs to ...
2. Finish layer - this can be bondo or other filler with a primer on top - for feather sanding to get smooth, just like bodywork people do. The reason this is used is only to smooth the surface and because it is easier to finish than the structure.
3. Release layer. This is glorified wax. Epoxy likes to stick to things, so you need something to keep it from sticking to your mold, or your mold will become part of your part. By the way, life is simpler if you can make your mold part of your part. It is relatively common to make the mold part of the part in car stereo stuff and other non-weight critical apps. Consider it, it is really much easier.

I have also seen people that make the structure of a mold and *carefully* apply tape with a gloss finish on it to get the shiny. Pretty slick. Fast and easy. Always will be some mold lines, but that doesn't always matter. It's fast, though it doesn't make a durable mold. You still should use mold release.


Vacuum bagging is easy if you have the right equipment. The vacuum hold everything together, and if you bake it, it dries fast.

The equipment is:
- Vacuum bag. This is sold, but any plastic sheet that won't stick to your work will do it.
- Release ply. This give the epoxy that is sucked out somewhere to go. It looks like blanket batting, but isn't.
- Breather ply. This is like the vacuum bag, but has jillions of tiny holes in it. This layer goes next to the part and lets the excess epoxy get away from the part. When the epoxy stops flowing, the holes close, and it acts like a solid sheet, sort of.
- Vacuum pump. You want to pull as much vacuum as possible, but you can also find the low on diminishing returns.
- Vacuum bag sealant. The Vacuum bag is just a sheet. This stuff looks like gum and you use it to stick the two sides of the bag together.
- Many people use a fancy nozzle to connect the vacuum, but I just stuck the vacuum hose in a small hole in the vacuum bag and wadded up some vacuum bag sealant to seal it. I guess I have a little ghetto in me.


Remember that I do things one way. There are other ways. If some body shop guy that does glass all day says something else, listen.