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AlpineCoupe
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Group: Forum Members
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Hello all, Im new to the forum and new to making composite parts. I have made a couple of splitter vents for a race car of mine and now am working on brake cooling ducts for the front air dam. My question is how to lay up the carbon fiber to ensure a reasonable release from the mold. It currently looks like this:   I was thinking I could lay it up (after sanding and smoothing of course), as is, vacuum bag it, and essentially make it as one piece. But as I read a couple of other posts on this forum I started to second guess myself. Any suggestions from the collective? Thanks in advance!
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Hanaldo
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Should be fine if you haven't got any mechanical locks, so watch your draft angles. That is essentially exactly how I made these Lotus Brake ducts, but the moulds were CNC'd.  
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AlpineCoupe
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Group: Forum Members
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+xShould be fine if you haven't got any mechanical locks, so watch your draft angles. That is essentially exactly how I made these Lotus Brake ducts, but the moulds were CNC'd. My draft angles should be good. Did you coat yours in gelcoat? And what did you use as the base plate? Thanks!
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Lester Populaire
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Group: Forum Members
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+xHello all, Im new to the forum and new to making composite parts. I have made a couple of splitter vents for a race car of mine and now am working on brake cooling ducts for the front air dam. My question is how to lay up the carbon fiber to ensure a reasonable release from the mold. It currently looks like this: I was thinking I could lay it up (after sanding and smoothing of course), as is, vacuum bag it, and essentially make it as one piece. But as I read a couple of other posts on this forum I started to second guess myself. Any suggestions from the collective? Thanks in advance! Bondo has extremely bad release properties. I would use pva as a release agent, even tho i hate pva usually...
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Mikerw
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Following this with interest!
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MarkMK
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If you're happy with the basic shape, in that it doesn't pose the risk of a mechanical lock, after sanding back the filler/bondo it would probably be best lay a couple of light fibreglass layers over the pattern
Even if well coated with a suitable paint system, filler/bondo is likely to pull away when it comes to creating an initial mould so the fibreglass skin will add some strength. Once the fibreglass has been roughly sanded, a thin skim of filler can then be used to create a surface smooth enough to apply a top coat.
The pattern coat primer and hi-coat gloss system that EC sells would be ideal, but some other kind of coating that can bond well to the bare pattern and provide a reliable release surface, after flatting and polishing, depending upon what's available where you are will also work
This will give you a female mould from which you can then create your final male mould using a tooling gel coat and fibreglass reinforcement
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AlpineCoupe
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Group: Forum Members
Posts: 45,
Visits: 2.1K
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+xIf you're happy with the basic shape, in that it doesn't pose the risk of a mechanical lock, after sanding back the filler/bondo it would probably be best lay a couple of light fibreglass layers over the pattern Even if well coated with a suitable paint system, filler/bondo is likely to pull away when it comes to creating an initial mould so the fibreglass skin will add some strength. Once the fibreglass has been roughly sanded, a thin skim of filler can then be used to create a surface smooth enough to apply a top coat. The pattern coat primer and hi-coat gloss system that EC sells would be ideal, but some other kind of coating that can bond well to the bare pattern and provide a reliable release surface, after flatting and polishing, depending upon what's available where you are will also work This will give you a female mould from which you can then create your final male mould using a tooling gel coat and fibreglass reinforcement Thanks for the replies everyone! I should have mentioned that I didn't plan on just laying the carbon fiber over the bondo. I'm still in the planning stages and thought I might put some gelcoat, or another paint like covering on it prior to laying the carbon down. I like the idea of the fiberglass to add some structure to the mold and having resin layer to lay up upon. I'll keep everyone updated with how everything goes!
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Hanaldo
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My mould was just CNC'd tooling board, primered and then sealed with tool sealer like EC's S120.
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AlpineCoupe
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Group: Forum Members
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+xMy mould was just CNC'd tooling board, primered and then sealed with tool sealer like EC's S120. Thank you, that's very helpful!
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AlpineCoupe
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Group: Forum Members
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Just wanted to say that I moved forward with primer and clear coat on this mold. Going to do some finish sanding and then seal the mold in some way. Thinking I might go with partall wax and PVA just took be sure I don't get any lock up. Can anyone confirm this to be a reasonable idea? If not, no offense taken I'd rather do it the right way! 
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