By Slimy38 - 1/25/2012 10:02:52 PM
OK, this is my second post (after an introduction!) so I thought I'd jump in with both feet!! I'm looking at building a kit car in the near future. The base will be a Lotus 7-esque design, but I want the bodywork to be all-encompassing rather than the exposed nature of a typical 7. Something along the lines of Tiger Racings GTA car is what I'm aiming for.
But I have no bodywork skills whatsoever, and the only experience with fibreglass was a couple of repairs to a motorbike fairing. Admittedly the repairs were very effective, if not exactly pretty! From what I've found so far, I'm considering the following process to build a panel; 1. The build of a 'buck' (if that's the right term?) made up of wooden formers with foam in between, and a light skim of filler for the surface. Oh, and an appropriate level of release agent! 2. A layer of GRP (300gsm chopped strand mat with bog-standard resin). 3. While the resin is still tacky, add a layer of carbon fibre twill mat. This would probably be using something similar to carbonmods skinning kit. 4. Those two layers left to cure, then continuing with the skinning kit a few layers of clean resin with a view to polishing right at the end. 5. The removal of the panel from the buck, and keying the smooth surface. (Yes, I am doing things 'upside down', and applying step 3 to what would be a rough surface!) 6. The application of some sort of reinforcement to the underneath of the panel. I was thinking of half inch square foam strips in a lattice pattern, with another layer of GRP over the top of that? And that's it. The plan is to build a panel that is reasonably stiff, has the carbon fibre exterior, but is reasonably easy to lay up (IE no vacuum bagging!). So I'm interested in opinions on all steps, good or bad. Particularly what people think will happen at step 3, when I add carbon fibre to the 'rough' side of a GRP panel.
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By Joe - 3/13/2012 6:20:10 PM
Hi, Slimy.
That sounds like a real awesomely and ridiculousely fun stuff going on here !!
I'll have to look at that profinish stuff, is it a particular type of fabric?
Profinish is a regular 200g/sqm 2*2 twill 3k fabric, they just "mist" it with some resin, so the weaves stay in place. Plus when you cut it, you dont have those tows coming of and grabbing everything.
This in my humble opinion is super great when you're alone and need to manipulate large areas. The downside is that it is a bit less prone to take serious curves on its own like a regular twill would, because resin makes it a bit more rigid. I was not able to make it work as easily as regular twill. But yeah, it depends what people call "serious curves", huh 
Another very good side of Profinish is that it will be okay if you want to put it "outside" a cube shape. I had VERY good results in working a 10cm*10cm on 1.5 cm high "cube", in one piece, no cuts anywhere. Weaves would look good and the edges of the "cube" mold would not protrude thru the fabric during layup. I had the same part made with regular fabric and it was a nightmare.
With regards to the process, you're saying spray glue it on to the fibreglass panel, then apply resin on top? Would the resin application be the same as if the carbon fibre was dry
I know people would use spray glue to hold their fabric in a mold while adding all their stuff. I know 3M 77 is known to work well for that. Prolly other glues would be okay too, but I've heared of this one only. So I'm with Maverick for your particular project. Yup, the fabric is applied dry on the panel.
And finally, to close this long and boring post, just my little opinion, if you're ready to make a project like that, go for the moulds too. Who knows? Maybe u'll need additional panels for your own use, or maybe even one day you could have someone ask you to build the same car. Then molds would be really cool. Very good luck to you and keep us posted
Cheers from Belgium.
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