You would certainly need to be making it in two halves unless it had a massive filler neck and you had a very small hand!

In pre-preg you would often have a split mould, lay up the pre-preg material into either side and then bring the two halves of the mould together and then (if you can get your hand inside) you could then put carbon tape inside over the seam to tie the two halves together before bagging and curing them off all at the same time. Using vac bagging, infusion or wet-lay I think this process wouldn't be possible and you'd need to make it it two halves - possibly with an internal flange which you could use to bond the two halves together securely.

--Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

still in the design stage at moment. got idea floating around in my head of best way to do it. will be two piece mould at least. the outer shape as to be right to aid removal from mould but i dont want to be far removed from shape of original tank. how many lairs of fibre are needed and how many should be kevlar ?

Whils trying to answer this question for myself I came across this thread;

http://www.bayarearidersforum.com/forums/showthread.php?threadid=145975

Don't know how I missed it before, but it confirms all of my theories about the process. Very detailed indeed!

With regards sealing, ethanol apparently will attack epoxy. I keep hearing this. The chaps I know who deal with such things will only use this;

http://www.frost.co.uk/por15-motorcycle-fuel-tank-repair-kit-3193.html

You would need to use a layer of kevlar as well. I think some composite tanks also contain an unburstable bladder, not sure about the motorcycle ones but IIRC the car ones are often obliged to.

With regards layup, to retain the pattern of the carbon in the finished tank you need to make the top and sides of the tank as a single, split mold. The base of the tank, where it can't be seen, is typically made from a seperate single part mold. The two parts are then glued together, there's usually a small lip or overlap.

The other option is to use a lost core technique, this simply entails making a foam plug in the shape of the finished tank you desire and hand laying carbon over the top then wetting out with a brush, building up the epoxy and then flatting down by hand at the end. The plug is then disolved with acetone via the filler hole. This is a much quicker and simpler way of doing things and an excellent finish can be achieved with a lot of sanding and a good eye!

Is there as specific type of foam for this? Would the fuel resistant resin also be resistant to methanol , dex-cool or other automotive fluids?

I would love to make a methanol reservoir and a coolant tank with the "plug" technique but it would be easier if there was 1 resin for both.

Thx for the info.

 



 


    A $1000 electronic device will always protect a 10 cents fuse

Ive read a few bits on tanks before. 

One bloke built a bike tank using the "lost foam" method and hand lamination, then using acetone to dissolve the foam afterwards.

There are quite a few tank sealers available in the classic car world that get used on ropey old fuel tanks.

Also motorsport often use a kevlar bag tanks in a composite box.