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Fiberglassing Plastics


bigboybanshee

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Couple of options here:

 

For a mold release using your current plastics as the mold, use car wax - lots of car wax. Get your plastics good and shiny if they're scratched by sanding them with thousand-something grit sandpaper. Apply several coats of wax and then put a thick final coat on and leave it there. Let your wax dry and then lay your glass over that. The finished product will peel right off.

 

If you want to make the mold from scratch, use styrofoam. Sand it into shape and glass right onto it. Then when you're finished glassing just pour gas on the styrofoam to melt it.

 

As far as the resin:cloth ratio; for maximum strength you want to have 50/50 by weight. You can either weigh each in turn as you apply (Pain) or just apply resin to the cloth and then squeegee as much resin out as possible without pulling the cloth fibers. You'll get damn close to 50/50 this way (trust me, I measured). For added strength you could use carbon fiber. Carb.com has some glass/carbon mix that's pretty cheap.

 

Either of the above methods will require that you use epoxy and not polyester resin.

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Wow, this is some really good stuff guys!! I can't thank you enough for the help/advice...I never thought about the fact that if I use my plastics for the mold it wouldn't fit right. LOL, I would have been so pissed too!!! Great info, I'll take all I can get for this project!! THANKS!!!! :D :D :D

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I was thinking of a solution to the mold problem and came up with an idea that should work:

 

Use the current plastics as the mold, but use the insides of them. Sand em smooth and then lay one or two layers of glass on the inside using the car wax method and then CAREFULLY peel it out once it cures. This should give you a very thin and almost perfect relief of your plastics. Then apply extra glass to the OUTSIDE of your fiberglass relief. By doing this you'll only be a couple millimeters smaller than the original plastics. The only thing that you'll have to be careful of is that you don't tweak the fiberglass while its thin and out of the plastic mold thus distorting the shape. You might even try drilling the bolt holes and zip tying it to the bike so that you know it'll fit and then glass the outside layers in position. When you've added several layers (I'd say 24 oz. thick at least) then you should have a fairly rigid piece and be able to cut the ties. For a general idea one 6 oz. thick piece of glass has about the same properties as the pain in the ass plastic containers that they put stuff like RCA cables in and that sort of thing. If it were me I'd use 6 oz. biaxial glass for the initial mold and then use 4 oz. carbon fiber or a 4 oz. carbon/glass weave for the outside layers. Either that or keep layering 6 oz. glass on the outside until you've got at least 4 layers. Carbon is evil to work with but its twice as strong - that's why you want to use a thinner fabric. So if you determine that 24 oz. of glass is strong enough, you could have the same strength with 12 oz. of carbon fiber. Carbon fiber is also incredibly rigid whereas glass will allow more flex (could be good, could be bad) but at the price of being fairly brittle. A small amount of kevlar fabric (2 in. kevlar tape should be ideal) would be excellent for reinforcing the bolt holes since the stuff is incredibly resistant to abrasion and will almost guarantee that you'll never snap a bolt attachment point. I'm guessing at the finished thickness of the fiberglass. You might have enough strength with 24 oz., or you might need more. Whatever you decide, take pictures and write up a tutorial so others can see how it was done.

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Wallrat, YOU'RE THA MAN!! I'm gonna print out your post and memorize it! LOL Once this project does go underway, I guarantee I'll take plenty of pics and write up somethin giving every step and detail to the whole process. I'm sure it is gonna be pretty time consuming but oh well, we'll just wait and see. THANKS TO EVERYONE FOR HELPING!!! :D

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Justin:

When was the last time your pc jumped off a cliff or ran 80-100mph down a 1/4 mile of whoops? How often do your knees bounce off the pc case?

Pick up your pc and slam it down on your desk a few times and let me know if the bondo starts to crack :) I'm joking of course!

 

Bondo is used for cosmetic repairs ONLY. For what your doing its fine...

 

Stan:

After seeing what K&T charges for their glass fenders I almost thought about making some myself. With the method I described you could mold what ever design you wanted and have a solid sturdy set of plastics, that would fit your bike perfectly :)

Its been slammed and fallen on its face while I was cleaning it. Not sure about the whoops, but I might find out because if it gives me any more problems Im going to toss it down oldsmobile. On the other hand, I don't see the radiatior cover or tank plastics taking much of a beating either. But I normally don't ride with my knees on them...

 

Take pics too, your write up will be a great post.

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