Carbon Fiber

[mrnoble]

Originally Posted by adciv

I think we'd be interested, but do not know the techniques for making it. Can someone post information on making it? I remember running into Carborundum a few years ago and was impressed with their material.

We have set up a vacuum press. Here's what we do:

• 3/4" thick plywood w/ melamine (resin doesn't stick to melamine surfaces)
• whatever the object is being formed around. This could be flat (thus the melamine), or some other shape. make sure it is covered in material that the resin doesn't stick to, or is intended to be part of the structure.
• epoxy resin
• carbon fabric
• more resin
• mylar sheet, for the smooth shiny finish that we are used to seeing on carbon
• nylon "fluff" to absorb extra resin
• "bag" material. this is very tough and stretchy plastic that is taped down to the melamine.

Talk to a supply shop, they can hook you up with the right materials. Oh, and you need a pump and a suction cup, too. These are not cheap. In fact, all of that will set you back a fair penny. Make sure you intend to use it for the long term before investing in all the setup, and make sure what you are using it for actually benefits your robot. We are using it as a wrap around a 1/8" thick Baltic Birch belly pan sheet. It makes it light, strong, and stiff.

[aldaeron]

Originally Posted by mrnoble

We are using it as a wrap around a 1/8" thick Baltic Birch belly pan sheet. It makes it light, strong, and stiff.

... and also electrically conductive. Be careful!

Solar car carbon fiber skins can catch on fire if the cells are not properly isolated ...

[MrForbes]

We spent a few minutes last night talking about "real" carbon fiber, then cut our claw parts out of 1/4" birch plywood.

We also made the center brace for our robot, we used a 2x6 since a 2x4 was a skosh too tall, and it was easier to rip the 2x6 to the proper width.

Engineering is an interesting game.

[Bryce Paputa]

We're using a whole lot of carbon fiber composite. We're using both a vacuum bag method like mrnoble (with thin aluminum replacing the melamine coated wood), and just doing a wet lay up of carbon and glass fiber sheets with epoxy and then compressing it on smooth, waxed surfaces. Using compression is easier, but you have to be careful with how much epoxy gets put in because there is less pressure trying to push it out of the fibers. If you use too much epoxy, the fibers will be farther apart, weaker, and heavier. You also have to make sure the surfaces are good ones, we've had issues with the epoxy sticking to some materials and with glass shattering under pressure when used.

[dchartley]

I haven't used carbon fiber or fiberglass on robots but I've used them extensively on electric race cars (Electrathon America). You can use just about any material (except styrofoam which will melt even through plastic) for a mold then cover with the heat shrink plastic you can buy for window insulation. Shrink it with a heat gun and its ready to use. If you want to make multiples of the same item it works better to make a positive mold (buck), then make a negative mold, wax the snot out of the negative mold (use release wax if you can find it) then make the parts. I never used a bagging system, only wet lay up, but if you coat the interior of the well waxed mold (I usually did 10-15 coats of wax on a new mold) with epoxy, then the layers of cloth, making sure all the cloth is coated and then put your buck on top (with the plastic cover if necessary) then add some weight and set overnight it will give results as good as many bagged systems. I'll post some photos in the gallery section.

Doug