Newbie: How to make CF sheet from prepreg 5mill Unidirectional CF?

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#1

I saw an auction $750 for 2x800 feet of unidirectional carbon fiber pre preg. Supposedly this is left over material from Boeing air plane manufacturing center?

This stuff weighs about 1 oz per square feet and although the thickness is not mentioned I’d guess around 5 to 7 mills thick (.005 to .007)
so about as thick as copy paper.

Anyways the price is cheap and I have never worked with carbon fiber before, or even fiberglass, so I’m wondering if it is possible to make a good looking Carbon Fiber veneer out of this stuff?

I figgure 3 layers with the middle layer at 90 degrees to the other two layers would work?

All the carbon fiber sheets I have seen are regular or twill pattern
I have seen only one unidirectional CF product and that was for a guitar on youtube, it looked nice to me. I’m worried about the unidirection though and worried fibers might fall apart. I’m sure the prepreg helps.

I would be making portable photo booths out of the veneer which would be covering aluminum skeletal frames.
we currently use ABS plastic veneer 40 mills thick and I’m looking for something that looks cooler and is lighter.

thanks for any tips on making sheets out of this stuff.

#2

It would work fine, but I’m gonna say it’s not for you. If you have never worked with carbon before then you won’t be set up for it, especially not for pre-preg. And if it’s ex-Boeing stock then it won’t be ooa pre-preg, so it is designed for autoclave use.

#3

agree with hanaldo, and also u need ooa prepreg for oven (if u dont have an autoclave) and also glass sheets (the size of ur veneers) as molds to get glossy perfect shaped parts. unless the finish is unimportant u can still use glass molds to bake the ex-boeing prepreg in oven and get strong parts but with very bad finished surface.

#4

well I ordered a small sample piece just to play around with. the seller also has some 3k regular weave CF, so I might just buy that instead, but I actually do like the unifiber look.

I do have a power coating oven, and I can get glass sheets fairly easily from a local glass place. the veneers only need to be 24x34" in size so they can be handled pretty easily by one person.

I’ve only found one thread on what happends to old expired prepreg CF
http://www.homebuiltairplanes.com/forums/composites/15227-what-do-cured-prepreg.html
Seems like the stuff gets crusty and dries out.

You guys are right I do not have an autoclave and they don’t look easy to build.

what would happen If I bought the roll and cut it down to 4’ long lengths and laid it on some flat glass and just let the prepreg dry out? could I then use standard OOA epoxy to make some veneers, Obviously the fabric will not wet out as good and not be as strong, but this is just for veneers nothing structural.

thanks for your thoughts.

#5

If you’re looking just for a cosmetic veneer for a photo booth, your best bet is to buy manufactured panels and just glue them on to your normal structure. If you’re trying to save money, you can try infusing them yourself over a sheet of glass. Look to spend about 500 bucks just to get your first prototype panel made if you’re not set up for working with composites at all

#6

no I’m not looking for a cosmetic veneer
the reason for CF is to save weight as these photobooths are transported around a lot and it’s no fun lugging around the boxes that weigh over 70 lbs. if i can get the total weight down to 50 lbs per section or less one person can manage it and we can then sell more vs the competition who has heavier booths.

I just saw some youtube videos where PPCF (prepreg carbon fiber) was sandwiched in between two thick pieces of metal sheet and baked in an oven and the parts turned out fine. but they were smaller parts around 1x1 ft.

I will probably be powder coating the finished carbon fiber sheets so finish is not that critical, as long as it is not that bumpy.

so any further thoughts? I have lots of steel plate that is 1/4 and 1/2" thick I can sandwich this stuff between. Just how much pressure do you need for the layers to bond well? 1/2" steel plate is around 30 lbs/sq foot is that enough? Maybe I will just have to order a bigger sample piece and try myself?

$500 is cheap for a first mold. I’m not some hobbiest that would faint at that numbers, just a small business trying to do something unique in our manufacturing process.