Mold making advice and fail.

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Mold making advice and fail.

Author	Message
simyboye	simyboye posted 9 Years Ago Topic Details
Group: Forum Members Posts: 9, Visits: 45	Hi there, New here and I'm trying to get my mold technique down but failed last night. Using epoxy gel coat and used AFH release agent x 3 and polished... This is the second mold I had made of the same part however on my second attempt when releasing the mold ended up with the mold breaking into many pieces. Any ideas? Used gel coat for two passes then 2 sheets FG matting for the strength however not sure what I've done wrong. Was the mold not rigid enough or not enough release agent? Many thanks in advance. Jay
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Hanaldo	Hanaldo posted 9 Years Ago Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	No where near strong enough. Looks like you've used surface tissue for one, did you just do 2 layers of that? Fibreglass is strong but it isn't THAT strong haha. Ideally ditch the surface tissue, it's junk. Put your gelcoat on and let that cure. Then do one layer of 225 gram csm and let that cure. Then do 3-5 layers of 450 gram csm. That will be strong enough. Looks like your gelcoat wrinkled a bit as well, how long did you leave it to cure and what catalyst ratio did you use?
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simyboye	simyboye posted 9 Years Ago Post Details
Group: Forum Members Posts: 9, Visits: 45	Many thanks for the reply. So you think it's simply the mold not being strong/ thick enough? I did this earlier and it was fine but inside is too sharp to wet lay and make the fender. Can't afford veri preg and tools etc.
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ChrisR	ChrisR posted 9 Years Ago Post Details
Group: Forum Members Posts: 363, Visits: 3K	You mould should be 2-3x the finished part thickness, so if you want a 1mm thick finished part your mould needs to be around 3mm thick. If you are using polyester resin, gel & CSM etc then as Hanaldo says 2 layers of gelcoat, let that tack off then (personally) I like to use 1 layer of scrim/surface tissue, then build up in 225 gsm layers of CSM to the desired thickness, then I like to put a layer of surface tissue as a last layer just to make it nice and neat
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simyboye	simyboye posted 9 Years Ago Post Details
Group: Forum Members Posts: 9, Visits: 45	Many thanks. I'll use csm this time. Will report back shortly. Thanks again
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MarkMK	MarkMK posted 9 Years Ago Post Details
Group: Forum Members Posts: 338, Visits: 2K	On another note regarding using the epoxy gelcoat, as opposed to polyester - it can be a little thicker and more prone to holding on to trapped air in corners, especially if laid on quite thick in the first coat. Probably best to make sure it's warm enough and applied quite thinly at first before awaiting a firm tack and laying down a second thicker coating. Might save you having to fill in little surface holes later. Don't ask how I know.
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Matthieu Libeert	Matthieu Libeert posted 9 Years Ago Post Details
Group: Forum Members Posts: 955, Visits: 3.4K	like above looks like your mould is to weak, you need a strong mould to make your mould pop out of the mould Matthieu Libeert Founder MAT2 Composites X Sports website: www.mat2composites.com
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Chris Scott	Chris Scott posted 9 Years Ago Post Details
Group: Forum Members Posts: 20, Visits: 235	Also if you plan on vacuum bagging the finished part, a strong mold will resist against bending/buckling/warping under the vacuum pressure. Sometimes even depending on the resins, ambient temperature, and size of the part.. the exothermic reaction from the resin might cause enough distortions to cause problems. I've seen this with aftermarket car body parts. So like everyone said, you want a strong mold. Fiberglass is cheap, I've too many times ended up wasting more time and money by trying to save time and money (ironically). Good luck! It's all about learning from failures! :]
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simyboye	simyboye posted 9 Years Ago Post Details
Group: Forum Members Posts: 9, Visits: 45	Getting there with the molds but that fender has some weird angles etc so jumped in the deep end. Done side panels with good results. Just got to master vacuum bagging now but going to do it later this year so will report back. If anyone has the same panels can help you with parts for minimal cost.
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