autoclave, carbon fiber, vacuum

[veteq]

Hello guys,

could somebody tell me about the autoclave proces to make carbon fiber,
where cann i buy a small benchtop system for rc building ???
all the info is welcom

kind regards,

roy bakker

[veteq]

there are plenty off sites that sell prepreg fibers to make youre own carbon fiber, if i`m right first it goes in a vacuum precision mold and then in the oven for around a couple off hours on 20 psi at 135 Celsius.

am i right,

are there some expert over here on this subject,

Roy bakker

[turmite]

Hello Roy,

I am by no means an expert but I do use carbon fiber in a wet layup system. I have never used the pre-preg due to the high temps needed to make it work. I do however use vacuum bags and a home built oven that will take the temp up to about 180* f. I think the wet layup/ with vacuum bag will work fine for rc parts, depending of course on how complicated the parts are.

MIke

[joecnc1234]

Hi I made composite airplane parts for learjet. no big deal just make your mold buy the pre-preg, lay it on your mold, bag it, make sure there are no leaks, vac it down, and bake it. I just bought a commercial oven at an auction for $150 easily converted for a vacuum line. any manufacturer of the cf will tell you the resins and temps and hg to cure the cf. and by the way the auto clave creates vacuum and surface pressure at high temp you shouldn't need that for rc

[turmite]

Hi Joe,

Is there any chance you have a couple of photos of the oven set up with the vacuum line conversion?

Mike

Originally Posted by joecnc1234 Hi I made composite airplane parts for learjet. no big deal just make your mold buy the pre-preg, lay it on your mold, bag it, make sure there are no leaks, vac it down, and bake it. I just bought a commercial oven at an auction for $150 easily converted for a vacuum line. any manufacturer of the cf will tell you the resins and temps and hg to cure the cf. and by the way the auto clave creates vacuum and surface pressure at high temp you shouldn't need that for rc

[joecnc1234]

Mike,
We just drilled a hole in the side of the oven, ran a steel tube and a couple of swivel fittings and an a/n fitting to the bag.

[11bravo]

What kind of R/C?
Planes or wheeled?
I do some composite work on amateur rockets so have a bit of experience.
For what your scale will most likely be, go with wet lay up and don't worry about an autoclave.

Vacuum:
Some will scoff but, if your parts will fit, an easy and inexpensive vacuum setup can be had in the form of a Seal•a•Meal.
Yep, you read correctly.
Mine will pull 20” Hg which is not a great as a for real and for true vac pump, but never had a problem with the results.
Also, the reason to run the vac tube into the oven is to maintain the vac in case the bag is not quite sealed.
The food saver idea seals it.
Removing outgas is another reason, but I’ve never had trouble with it.

Curing oven:
Check out the plans available here:
http://www.shadowaero.com/COMPONENTS.htm
You can adjust the size to fit your needs.

Also, check out the videos they sell.
They are about building rockets, but the info translates over.
I also hear good things about the books and videos available from Fiberglast.
I have never looked at any of them though so don’t shoot the messenger if they are bad.

Use actual epoxy, not polyester based stuff.
PE stinks and is BAD for you.
Good laminating epoxies can be had from: from least expensive to most
US Composites
Aeropoxy <my preferred epoxy and the least expensive place I’ve found that carries it
West Systems <meant for boats, cannot be cured at much of an elevated temp

[High Seas]

Originally Posted by 11bravo What kind of R/C? ....Use actual epoxy, not polyester based stuff. PE stinks and is BAD for you.....

I beg to differ on PE is BAD for you.

I know of no one suffering from long term use of polyester resins - been in Boats and the messin with resins for a very- very long time. More than several close friends can no longer use epoxy...because Epoxy can, and will eventually "bite you". You will develop an allergic reaction - so keep contact down.
Yes, Poly does smell bad - use a fan!
DOWN SIDE - for exotics (carbon, kev, etc) - you got only 2 choices epoxy or vinylester.
Use epoxy where it makes sense - exotics and high strength/low weight aps - and yes autoclave for maximum performance. For less critical apps, poly will get you there at less cost -- but with out the exotic appeal.
Jim

[11bravo]

Long term, most of us doing hobby related things will not end up with sufficient exposure to get to the point of developing an allergy to epoxy.
My point, and I did not point it out, was in reference to the fumes given off while working with it.
What I read when starting research into using them said that with PE you NEED to wear a respirator.
Not that one shouldn't wear one when working with epoxy, but that with PE it is much more important.

[joecnc1234]

11bravo,
great idea on the seal a meal. should work well.
Joe

[11bravo]

I, in no way, can claim credit for the idea; just sharing what others have shared with me.

As long as your part will fit into the bags, seems real close perfect to me.
Quick, easy, not very messy, and the vacs can be found cheap at flea markets, garage sales and the like.
Unless you're going for maximum vacuum.
Other thing is that, at least with epoxy, the bags do not stick.
Cut them too big and I've used them over and over.
One draw back is that one side of the bags always seems to have some texture to it and that transfers to the part, but that can be dealt with.

[High Seas]

PE won't stick either (to the bags). I'll add - if you can't find a seal-a-meal type - for vacuum, you might look for a hand held brake bleeder - about 30bucks or so new - who knows at garage sales?!
Been toying with using the old shop-vac - but need to let some air cooling to it too so it won't melt down. If I get it going - will share the lessons learned.
We used heaps of BEAR plastic strapping tape as a release on both PE and epoxy. Tape on the mold - layup over the tape. Might be a bit of a prob' with the heat if you "cook" it.
Just sharin' Jim