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Aquaman
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Group: Forum Members
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Hi all, First of all I hope this is the right section to post my query and I can get some expert help and guidance. I plan to make my own rc car shell as the one on the market for my car is very brittle and snaps at any point of contact. The requirements of the shell I make are that it has to be strong, doesn't crack/snap upon impacts, must be flexible and long lasting. The reason for these requirements are because the car will be flipping over and landing on it's shell, rolling over multiple times and having impact on the shell from various angles etc..., the car weighs around 15-20kg I believe. I don't plan to make a mould but rather use the inside of the shell as a mould as I figured it'll save me time, money and it wouldn't look much different from being slightly smaller. So far I have thought of putting down 1 layer of Black, 200g Diolen Fabric in a 2/2 Twill weave for aesthetics. Following that with 1 layer of Aramid 2/2 Twill Weave 300g Fabric Cloth. This will be followed by 2 or 3 layers of 300g Chopped Strand Mat (fibreglass) then maybe another layer of 200g Diolen Fabric in a 2/2.
What do you guys think of this plan, will it be suitable for my needs? Will it become too thick? Is it possible to bond all those fabrics together without them coming apart easily? Any suggestions and advice will be greatly appreciated.
Also to note I won't be using a vacuum or anything just laying everything down by hand and using a brush to spread any resin.
What else would I require for the job in terms of the type of resin that can be used on all the materials I will be using and also any sort of coating that will go on my mould (inside of rc car shell).
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Dravis
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Group: Forum Members
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Hi there, What is the shell for your RC car made from? If it is made from polyester fiberglass you will have some trouble using it as a direct mold. If the shell is nicely painted on the outside, you should really take the time to make a mold from it, then you can polish the mold and get a nice finish on the CF shell. How big is the shell? At How many points does it fasten to the chassis? This will determine how many layers you need. You could probably make a very strong impact resistant shell by just using a few layers of Carbon/Kevlar/twaron mixed fibre. Putting glass fibre in will only make it thicker and heavier, not much stronger. You could consider using EC flexible epoxy resin.. If you do make a mold, then maybe you can sell a few shells to other users of the same model of RC car? 
Personally I would use Twaron as outer layer, it has a very nice CF pattern, somewhat enhanced by the different shine of the CF and the Twaron tows, and it is very impact resistant.
If you insist on using the inside of your current shell as a mold, and are not worried about the outside finish on your new shell, then you may get away with just waxing it very thoroughly.
As to tools, do not rely on a brush, when doing larger areas of hand lay up, get a roller, the EC bristle roller is very good, but a b. to clean ...
Good luck
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Aquaman
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Group: Forum Members
Posts: 3,
Visits: 60
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Hi, The stock shell is made from ABS plastic I believe and is brittle. The shell is of 1/5th scale. After making the shell I would only need to drill 4 small holes for the body posts. Making a mould will just result in more money being used and I really only need to make a reliable shell for 'bashing' as we call it in the rc hobby. Using a few layers of the fabrics you mentioned will make my costs go up quite a bit as those fabrics aren't cheap and I have to take in to consideration the cost of other things such as resin, gloves, gel coat etc... I'll look in to getting a roller also. Dravis (02/07/2013)
Hi there, What is the shell for your RC car made from? If it is made from polyester fiberglass you will have some trouble using it as a direct mold. If the shell is nicely painted on the outside, you should really take the time to make a mold from it, then you can polish the mold and get a nice finish on the CF shell. How big is the shell? At How many points does it fasten to the chassis? This will determine how many layers you need. You could probably make a very strong impact resistant shell by just using a few layers of Carbon/Kevlar/twaron mixed fibre. Putting glass fibre in will only make it thicker and heavier, not much stronger. You could consider using EC flexible epoxy resin.. If you do make a mold, then maybe you can sell a few shells to other users of the same model of RC car?
Personally I would use Twaron as outer layer, it has a very nice CF pattern, somewhat enhanced by the different shine of the CF and the Twaron tows, and it is very impact resistant.
If you insist on using the inside of your current shell as a mold, and are not worried about the outside finish on your new shell, then you may get away with just waxing it very thoroughly.
As to tools, do not rely on a brush, when doing larger areas of hand lay up, get a roller, the EC bristle roller is very good, but a b. to clean ...
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Aquaman
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Group: Forum Members
Posts: 3,
Visits: 60
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Would appreciate some more of your advice guys.
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baja_patient
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Hey man, what you wish to attempt is a huge undertaking, trust me. I made a shell for my bajas, took me many attempts and a lot of materials to get it looking right. You won't be able to wet lay it i'm sorry to say. Especially if you don't wanna make a mould. Mine is still not perfect, but the best part i made was the nose. All made with infusion with moulds from an original shell. Using twaron would be good, mine are all carbon, n carbon glass. I will be trying a hybrid fabric too in future. Prior to these I had little to no composites knowlwdge, feel free to ask about anything you need. Sorry about the order of the pics! but as you can see, even with the mould, the first attempt was a major failure to say the least. High compaction was needed. But as I progressed my parts got better and better. Final product painted with silver auto paint and 2k clear. I wanted to do this, because I love making stuff, but it was waaay more expensive than just buying one. Cheers!        
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carbonfibreworks
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Group: Forum Members
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Hi AquamanI would say you are using too many layers and with a wet lay you will have a very heavy shell, you can use you own shell as a mould as I have made parts in a similar way.As your original shell may have some flex you need to put some strength into it and a good way is to cover the outside with plaster of Paris ( I have actually used the vacuum packaging that comes with some items as a mould  ), you could if wished now use an envelop bag and vac bag or infuse. If you do not have suitable equipment you can wet lay then place in some perforated film then fill the cavity with sand. I know it sounds crude but the weight of the sand will keep the fabric in place and apply pressure to to more complex shapes of the mould to reduce the risk of bridging. Best of luckChriswww.carbonfibreworks.co.uk
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Matthieu Libeert
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