Composite Woes

General Composites Discussions Composites Talk
#1

Man I bust my b*lls to make a part and half the time they come out like crud. Case in point. see photo.

It was a male mold, one layer of twill carbon, and one layer of 6oz f/g cloth, epoxy resin.

Got all kinds of small wrinkles - I counted 11 of them. Three small areas of the panel did not cover because the cloth shifted before full vacuum was achieved. It is now just a side project that I will work on as time permits. Material cost was around $75.
I tried using a sinlge piece of f/g and a single piece of c/f. I didn’t want any seams showing.

The panel weighs 1 pound & 6 ounces. I did reinforce the backside with a layer of multiaxial carbon 19oz. The glosy glob you see on it is where the epoxy soaked thru the laminate. No big deal as i am going to surface coat that side and sand it smooth, then clear coat paint it.

I need to make a good left and right panel for a customer but this job has me upset.

http://s210.photobucket.com/albums/bb186/Fastrr_photos/SinfulDragon_CarbonFiber/?action=view&current=f4isidea-1.jpg

#2

just an idea. if you plan to fill, clear, sand, clear, sand, clear, sand,clear, sand anyway why not ditch the bagging all together, wax the male master, use spray adhesive to get the fabric laying down nice everywhere, wet out the exposed side the best you can. sop up the excess resin with a sponge or rag then once its dry pop it off and wet out the back side if needed.

#3

hee…do you do all this in your apartment, or just a carpeted work area? Must smell wonderful in there when going to sleep at night!!

don’t spill anything :wink:

#4

Fastrr,

did you lay the carbon over the original fairing and then bag over it?

It might be worth trying the green stretchlon bagging. It’s incredibly stretchy and you could probably get it so that there are no creases at all.

#5

I tend to think the small wrinkles came from the breather fabric. Also the fiberglass and c/f needed a few relief cuts to make it around sharp bends. I am using the original as the mold. I use stretchlon 800 and believe it or not there were zero wrinkles in the bag film and no pleats were necessary. I think this is just a case of do it and learn from my mistakes. I plan to do another panel tomorrow so I’ll post up once i have it released from the mold on Saturday or Sunday.

Once I get this order done I should be a “pro” at making these type of panels.

Barely any smell at all inside my apartment. The part was wetted out then imediately vacuum bagged. The epoxy i use has not got much odor to it.

#6

Ya I didn’t even think about the breather, why not try putting the bag right over the cosmetic side and the breather and bleeder between the mold surface? With Vacuum bagging it’s just the compresssion that you are capitalizing on to bleed the excess resin out, so it shouldn’t matter which side the bleeder/breather are…or should it, perhaps my reasoning is off, it’s been a long day:(

I just realized that it does matter which side the vac is on, forgot what I just said, why not try and somehow rig the vac source from the side of the mold, through the mold if you konw what I mean…

#7

I wonder if i just used release ply and NO breather if the part would come out better? I know it would be resin rich for sure but i don’t care so much about that for these cosmetic parts. Other than being resin rich would there be any other problem with not using breather fabric? What about using no peel ply and having just release ply and then the vac bag?

Actually i think someone did suggest that, to just squeegy off the excess resin to the sides of the part. Would this be done under full vacuum or no vacuum?

I would put the breather under the cf and fg cloth but then the part would grow by at least .030" and I think it may produce a lumpy part. Not sure about that theory though.

#8

definetly use breather. if you try to bag a part without breather you will not get any good bag presser, and the part will come out much worse. I would try leaving out the bleeder, and really make sure your peelply, breather and bag do no wrinkle. after the part is bagged pull on the bag with your hands and a rubber squeegie to smooth the bag out… why not just sand that part down you made and put a overlay on it? it will be cheaper than making a new one and wouldnt weigh too much more, just a thought