Simple methods for molding fiberglass and carbon fiber

Here's a couple of low cost and quick procedures I use to manufacture simple parts using fiberglass and carbon fiber. While it's not the best method for producing parts that see structural loads (some form of consolidation like vacuum bagging/pressure molding to reduce internal voids should be used for that) or parts that need to have an extremely high finish leveI, I have molded everything from simple car parts to subwoofer enclosures to costuming/theatrical props using these methods.

Step 1 Materials

Clear packing tape
Blue foam insulation- available at many home improvement stores
Laminating resin- polyester resin and epoxy resin ( I use Bondo polyester resin for fiberglass and West Systems epoxy resin for carbon)
Acetone
Paint brushes- I use a short bristled brush, sometimes I just cut the bristles down to anywhere between 1/2' to 1" llength
Mold release paste wax-available from Aircraft Spruce- http://www.aircraftspruce.com
Woven fiberglass cloth and/or chopped strand mat- often called CSM
Woven carbon fiber cloth- available from Aircraft Spruce- http://www.aircraftspruce.com
3M Super 77 spray glue (optional)
Rubber gloves
Filtering mask

Please use proper safety equipment when working with resins and fibers. Carbon fibers are extremely sharp when cut and the use of resins and melting of foam can produce nasty vapors.

Comments

[tinker234]

cool hey buy a frame a engine a car in the works

[crowd9]

I imagine the final product has to resist compression/suction from air forces, and not vibrate/flap during a race. How many layers of CF did you use for the parts on this project to ensure strength?

[Honus]

It was so many years ago I honestly don't remember but it was several layers.

[nixnope]

Nice info! Will need to try this!

[ferrous]

ahahahah! brilliant!

[MAXcenter]

Woow! Nice idea, Boss...
I like the subwoofer idea! Will try to build one for my car too...

[stevo67]

Honus you are a huge inspiration, I love those sketches, and thank you for your most helpful and detailed instructional. I am going to hook in and make my own panels for my circuit car. Cheers from Down Under.

[Honus]

Thanks! Make sure to post pics when you're done!

[Bergzee24]

You mention using clear packing tape to seal. Is there a reason why you use clear over the brown packing tape?

[Honus]

I use clear because it's non absorbent. Brown packing tape would soak up resin and it's also not as flexible.

[mrlunna13]

YOU ARE A TRUE MASTER CRAFTSMAN!! Wow it is the best and most descriptive instructable. I was just going through the "fiberglass" ibles, and saw yours. Couldn't stop reading, I now have to wait till tomorrow to start my cowl induction hood on my truck and center console. 
Thank you so very much!!
Mr. Lunna Xiii

[Honus]

Wow- thanks! If you have any questions during your build just let me know and I'll help out as best as I can.

[dk-info]

 Just came across this instructable, looks great, I am trying it this weekend. What did you do with the Acetone/foam sludge? Soap and water cleanup?.

Thanks!
David

[amcayanan]

NICE IDEA. THANKS FOR SHARING!

[ferrous]

I was taught to coat the foam with thinned down white-glue as a sealant, then heat-wax as a mold release... do you think the packing tape method is superior? if so, why?

[Honus]

It doesn't really matter as long as it's sealed.

[ferrous]

Thanks for the tutorial! Its nice to finally see this job laid out so logically and nicely.

[candle360]

I had a question about making something like a cold air intake and box. How would you make the positive mold tube? I thought of using the styrofoam but I have a problem with how to mold it. Any suggestions on what I should try to do? It's going to be a 3 inch wide intake.

[Honus]

I would just carve your foam to shape, then wrap it with packing tape. Now coat it with a mold release wax and then lay up your cloth over the tape. After the resin has cured you simply melt out the foam and you have a finished part.

[candle360]

What about the box? And I plan on carbon fiber, what other steps do I have to take to cure the carbon fiber to make sure that there's no problems later with it? I've heard that if you do cure the carbon fiber right the resin used yellows and that you must also bake it.

[Honus]

What do you mean about the box? Just carve the box shape out of foam as well. As long as you lay up the carbon properly you shouldn't have any problems- an airbox isn't a structural component. You can give the finished carbon part a clear coat if you want to help protect it. Some resins yellow more than others- for the best strength and finish use an epoxy resin instead of a polyester resin.

[candle360]

Alright, thanks for the information. Great instructable by the way.

[Blue_Flame]

First off- great instructable, i've been using the wet lay-up method for a while now and its slow and tedious, even if it does get rather good results. I do have a question to ask though.........is it alright, with this method anyhow, to forego the firbreglassing at the start and just go straight to carbon?? if so, yay!! if no, why not?
Thanks again for the brilliant instructable

[Honus]

You can work directly in carbon. The issue is surface finish- you'll get a much nicer surface finish if you make a mold first.

[dvalued]

Wow.. I'm seriously thinking about getting a beater VW Bus and redoing the entire body in carbon fiber.. Obviously, this wouldn't be everything I need to know, but this is a great primer!

[candle360]

great instructable man. I was wondering where you could buy carbon fiber cloth, maybe even blue carbon kevlar cloth. I would like to make quite a few things including a lap top cover, full ram cold air intake kit, and a speaker box

[candle360]

haha, sorry. read into it a little more and saw your links. thanks man!!

[R4NS0M]

I agree with everyone! This is one of the clearest and most concise instructables I have come across so far. I'll be honest, I wasn't searching for fiberglass molding methods when your instructable surfaced, but now I am anxiously intrigued and looking forward to experimenting! thank you very much! :0)

[CementTruck]

I just did my first attempt at a combination fiberglass seat pan/rear fender for my motorcycle and am not happy with my work at all. The cured fiberglass is not as stiff as I had hoped, even with 4 layers of mat and plenty of resin. I applied the apropriate amount of hardener to the resin for the ambient temperature as the table on the side side of the resin container specified. Do I need to apply more fiberglass layers? More hardener? More Resin? Does more hardener make the resin harder, or does it make it cure faster? Please help!!!

[Thenwcp]

I agree with Honus.. more layers will make a harder mold, also going with what he first mentioned about load bearing parts. Vacuum sealing will help. Get some large plastic sheets (you can get some at home depot or lowes it's used to keep floors clean when your painting walls) have the fiberglass on the mold and make kind of an envelope with the plastic sealing the ends with duct tape except for one corner. stick the hose of a shop vac in the corner and seal it with duct tape. It's okay if it's not perfectly air tight, but within reason. The pressure compresses the fiberglass layers together making them stronger. the vacuum pressure isn't large but think that even if it's only 5psi vacuum that's 5 pounds sitting on every square inch so on a 9ft(squared) area that's 6480 Lbs pressing on that surface area.

9ft(squared)= 1296 square inches therefore 5lbs/inch squared*1296 square inches = 6480 Lbs

[CementTruck]

Thanks Thenwcp. I have used 4 layers of woven cloth and resin. I'll try your solution of the vacuum on another project, but I think I'll just go back to good old fashioned steel and welding for now. I'll do the fiberglass to make the thing pretty, but not for structure. Thanks again to both of you.

[Thenwcp]

oh and I almost forgot... the resin will not stick to the plastic sheeting

[Honus]

More hardener won't make the resin harder. Generally speaking, CSM isn't going to produce as stiff a structure as woven cloth. You could try laying up a couple layers of woven cloth and see what that does.

[cory.smith]

Sweet action! I have done a lot of fiberglass, carbon and kevlar work, and have never really been able to explain the processes this effectively! Nice! I really like the subwoofer in the tire. I might have to try that!

[Honus]

Thanks! You wouldn't believe how good the sub in the tire sounds- and you get to keep your trunk space. :)

[Thenwcp]

Another good one is the 8" sub under the seat, perfect for people who like the thump but don't want to worry so much about "disturbing the peace"

[crampedyogapositions]

could you build a guitar out of carbon fiber using this meathod? and if so how strong would it be? or should i just make wood and coat it with carbon fiber?

[Honus]

I believe you could, and if done properly it would be very strong. I honestly can't say exactly how strong a guitar needs to be....

I also don't have any idea about the acoustical requirements, cavity volume or number of necessary layers, etc. I can say that you would probably want to make a mold and then vacuum bag the carbon to reduce any internal voids that would cause unwanted resonance.

You might want to check out an article in the current (Summer) issue of American Heritage's Invention & Technology. The article is about how Charlie Kaman, a famous helicopter engineer, invented the Ovation guitar using a molded body.
http://www.americanheritage.com/inventionandtechnology/
http://www.ovationguitars.com/?fa=history

I also recently saw a TV program that showed the construction of a molded carbon fiber cello. It was pretty amazing stuff.

[rc jedi]

it is very hot here 100+. An auto repair guy sez the hardener will go bad quickly at these temps. He sez resin is ok, but get new hardener just before a project. I always have had hell is this true?

[Honus]

I'd say that's probably a safe bet. Hardener for polyester resin is pretty cheap anyway.