Body panels for a kit car


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Joe
Joe
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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 Wink

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 Wink

Cheers from Belgium.

 



 


    A $1000 electronic device will always protect a 10 cents fuse
Slimy38
Slimy38
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Nah, I don't want to buy a roadworthy car, part of the fun is building it up from scratch! This is going to be a project spanning a few years, and I'm starting with raw materials for everything. Turning a few lengths of steel, some fabric and some chemicals into a drivable car sounds like good fun to me.

I'll have to look at that profinish stuff, is it a particular type of fabric? 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? 
MAVERICK
MAVERICK
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For a 1-off i think to locost guys are not completly right, you have to factor the finishing time on the pattern which would not be much quicker than finishing the 'skinned' carbon part, then there's the added cost of the materials for the mould (for a car this woudl be quite a bit), you would need a reasonably smoth surface to put the carbon on but a quick blast over with 40grit in a DA will provide that easily, as for appling the carbon down neatly theres a simple method that works great... spray-glue profinish in neat peices (most 'panels' should be possible in 1 peice) the profinish cuts neatly and stays straight for large panels its ideal, doing the skinning build-up onto this should be easy.

Sure making moulds would be the ideal solution, but to get good cosmetic carbon panels from these you would definatly require infusion, your not gonna be able to wet-lay somthing like that and get away with it!

If you want the project to get off to a good start I would recomend buying a complete roadworthy car as you starting point it'll be cheaper than building and you won't have all of the IVA worries and build nightmares to contend with. cool sounding project though!
Slimy38
Slimy38
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Thanks for the reply. I don't know what I'm building yet, it'll be a Lotus Seven chassis but more of a body on top compared to the simple panels on a seven. Most importantly will be provision for a roof!! In a perfect world I'd do something like the Donkervoort GT;

http://www.thesophistiques.com/2011/10/donkervoort-d8-gt-compromise-they-dont.html 

I posted the same question over at Locostbuilders, and found that my plan was a little bit too ambitious. I had thought that I could lay the carbon fibre in one piece to preserve the pattern, but having looked at the size of panel and potential complex curves there is a good chance I would fail at that point. There was also the point that if I laid carbon fibre on anything but a completely smooth surface the ripples would show through in the fabric. So I'd have to smooth it down first before applying the carbon.

In general people say it could be done, but the traditional 'buck then mould then finished piece' approach is actually not as difficult, costly or time consuming as what I was planning to do. All I need to do is figure out how to do the carbon fibre whilst preserving the pattern!
MAVERICK
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Hey Slimy,

Thats a pretty ambitious project! Basically if your only looking to make a 1off and weight isn't critical I don't see a problem with the method, there are a couple of things that I've spotted though... Resin will like to stick to body filler, wax and PVA will help but as your not bothered about the inside surface finish you could use a trick that I came up with (at a small fee of course!) I basically stick release film (the good quality blue 15micron stuff) over a pattern using carpet spray glue, it sticks well enough for the job and it guarantees a release, I'd be tempted to go down the route of woven fibreglass and epoxy for the first few layers, you'd be able to build the panel at half the weight that with choppy and pe resin, the plan for a foam rib system on the inside sounds cool though.

With the little bit of skinning I have done I found it easiest to apply a couple of coats of topcoat, sand it down to 400grit with a DA sander and then lacquer it with 2-pack clear, it's suprising how quick you can do it.

By the way what is it your building? i've got a westfeild (with the odd bit of carbon!) I build mine years back and found that was enough of a challenge, sounds like your going really deep!  
Slimy38
Slimy38
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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.
GO

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