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Pustil
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Hi guys!
My friend is building 400+ HP Alfa 156 and wants carbon fibre bonnet, but in Czech republic is impossible to find larger carbon fabric than 1,2m wide and that's not enough.
So I want to ask you. What's the best way to made some big parts? Is it possible to connect 2 fabrics together in a center of part with some good looking finish? Or It's better to buy wider fabric and pay a lot of money for shipping from UK to Czech republic? That car is really low budget (car,engine and upgrades are less than 3000 gbp) and the prize is very important, but I want to make parts good looking too.
Thanks for your replies
-------------------Amateur from one little garage ----------Sorry for my English ----------------------------------------------
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Hanaldo
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A simple 'v-joint' is the most common aesthetic method of joining two pieces of fabric.
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Pustil
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Group: Forum Members
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Ok, thank you for your reply.
That's exactly the process that I never used or saw it before, so I have no idea how to do it, and I can't find some quick tutorial here or on the internet.
I don't need some "step by step" video, only quick description of process, but nothing to find. Maybe it's only my mistake, that I can't find anything, but I'll be very appreciate and happy for every advice or link.
-------------------Amateur from one little garage ----------Sorry for my English ----------------------------------------------
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scottracing
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What process are you going to use? Wet-lay or infusion? You can use spray tack or resin thinned down as a tackifier to place the material into the mould. Or you can use tape on the back edges where the join.
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Hanaldo
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Group: Forum Members
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A v-joint is very simple, but tricky to pull off nicely with dry fabrics. The method is as straight forward as laying your first piece of fabric into the mould so that the visible edge is down the middle of the part. Then when you lay your second piece of fabric, you flip it over so that the weave is running 45 degrees in the opposite direction. When you lay it into the mould, you overlap the first piece of fabric by about an inch. Then you can continue the rest of the layup however you like, you don't need to do a v-joint for every layer.
The trick is that dry fabric will fray and v-weave finishes only look nice with a very crisp cut edge. So if you are doing wet lay, then this can be very hard, because as you brush the resin onto the fabric you will pull some fibres and end up with a messy edge. Infusion is some what easier, you just need to be sure that the fabric don't move and pull your v-joint out of alignment.
I would recommend practising this a few times before trying it on the actual bonnet. Alternatively there are other ways to make a feature of of joins in the fabric. My personal favourite is to use a strip of spread-tow fabric down the middle of the mould, and then overlap the 2 pieces of regular fabric behind that. Or a strip of Easy Composites unidirectional ribbon tape is a very easy method that can look very effective. If you were to use that method, I would recommend offsetting the join slightly so that you can do 2 strip's of the tape, ending up with a 'racing stripe' sort of look.
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Pustil
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Thanks a million for your posts
I'm going to use infusion process.
My idea was to fix fabric with paper masking tape, cut in the line and put into the mould next to the second one (only in visible layer).
I'll try your advices with some leftovers and see what is best for me.
-------------------Amateur from one little garage ----------Sorry for my English ----------------------------------------------
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Hanaldo
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Do NOT use masking tape! Masking tape is impervious to resin, so it will prevent interlaminar bonding and lead to delamination between your layers at the joint. If you can get Airtech Airhold pressure sensitive tape then this will work. Otherwise, 3M Super 77 or another type of spray adhesive will do the job too.
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Pustil
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Group: Forum Members
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Hanaldo (08/04/2016)
Do NOT use masking tape! Masking tape is impervious to resin, so it will prevent interlaminar bonding and lead to delamination between your layers at the joint. If you can get Airtech Airhold pressure sensitive tape then this will work. Otherwise, 3M Super 77 or another type of spray adhesive will do the job too. As I said, It was my idea of "what to do", before I wrote here. Now, after your advices, I know much more how to do it and I'll try it next time in my garage.
-------------------Amateur from one little garage ----------Sorry for my English ----------------------------------------------
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PAUL S
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I have been having some good results doing wet lay without the material fraying by marking out the first layer of material using templates then overlaying the marked cutting line with self adhesive plasterboard mesh joint tape, then when you cut through this it keeps the cut edge together, and being a mesh does not stop resin getting into the material below. The mesh stays on the non surface side and is hidden from view by the next layer as well. This stuff, it's made of plastic/fibreglass and quite cheap.
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scottracing
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you wouldn't believe how many 'professional jobs' Ive seen that have used masking tape in prepreg layups!! shocking.
I should have stated when I said you can use tape, do not use masking tape! Ive heard of many a layup going up in smoke cause of the stuff!
Good tip on the plasterboard mesh tape Paul, will buy some of that and give it a try at work.
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