Mirror copying a shape/object

[Rocketman]

Another thing you can do if making the core is a lot easier but for the mould you require a cavity. You can make the core and then cast that into resin and let that set.

 

[Wendelspanswick]

That's a good idea too..

I've just stumbled on this on ...tube you... Starts off crude but boy does he achieve..

I was also going to ask.. Once you have created the shape/forme/plug would it have to be cut in half to carbon fibre it.. If you see what I'm saying, how would you get the mould out? Unless the carbon fibre was made as two halves and then joined..

Very interesting this thread now..

In a commercial situation you make your plug, a solid replica of the finished item out of polystyrene/wood/plaster/chicken wire etc. When you are happy with it you then cover it in release agent and use this to make your mould, this can be a single piece mould for say a half sphere or in 2 or more pieces for more complex shapes.
Moulding a fuel tank with a female mould so that the finished and polished surface is on the outside is complex as you would need to lay the material/resin in each half or segment of the mould and then glue the two halves together.

The quick way to do it would be to carve you tank out of a block of solid foam, cover in resin and mat, cure it and then dissolve the foam out from inside the finished tank. The problem with this method is that you end up with a rough surface on the outside of the tank that needs filling and sanding.
You can improve the outside surface by using Pre-Preg, a material pre-impregnated with resin, and vacuum bagging the whole thing whle it cures.
We use to use this method to make the beds for CT scanners.

As a note all my knowledge on high tech composites is circa 1990 so it's 25 years out of date but the company I worked for was at the cutting edge of technology, making amongst other things:
Cockpit safety cells for F1 cars.
Mammography plates for breast cancer screening.
Mudguards for Rapier rocket launchers.
Carbon fibre grappling hooks for special forces.
The first composite body panels for Aston Martin.
The interiors of Shorts aircrafts.
It was a brilliant firm to work for, I got to play with carbon fibre, Kevlar etc but we were bought out by Courtaulds who relocated the factory from Somerset to Coventry so I opted for redundancy. No offence meant to Coventry but I am a country boy at heart!

 

[Noods]

That is fantastic stuff.. I've got plenty to think about now..

 

[CRB]

Mudguards for Rapier rocket launchers.

All the high tech bits......and mudguards.

The lads who did our basic GRP work turned out some good stuff, but it would certainly not be anywhere near the standard required for most of that stuff.

 

[DanielW]

Chicken mesh and a few layers of papermachie

 

[Wendelspanswick]

Yea it was weird that we only made the mudguards but they had to protect the tyres from the rocket blasts.

 

[KemppiFrog]

Having been through this process in boat mould construction, lots of mirror image stations, then fair the surface with ribbands and filler, often the moulds are split lengthwise. But for a bike tank, making a female mould sounds a bit tricky; I presume you want the carbon fibre to feature in the finish, as your pic? So sanding and fairing after moulding over a male mould is out?

 

[graffian]

I
The quick way to do it would be to carve you tank out of a block of solid foam, cover in resin and mat, cure it
As a note all my knowledge on high tech composites is circa 1990 so it's 25 years out of date but the company I worked for was at the cutting edge of technology, making amongst other things:

My knowledge is from a similar time, but mine is not professional in anyway I however make did make bike petrol tanks.
I used foam core and wet laminate on the foam. I was just very careful with the carbon and put a flow coat of resin on.
It usually ended up with a smooth surface, maybe a few jaggies if I had ended a bit of carbon near a curve, you can press
them down with peel ply and flow coat later, you can always sand back and put another coat or clear or even paint.
The sealer to use was marine fuel tank sealers, which all seemed to come by 200L drums, I went round the boat places
with a milk bottle and scrounged some, A mate put petrol straight in a tank I made for him and emptied it after the races.
I left samples of laminated carbon in unleaded and after 6 months they were still crisp and looked OK. The tech bloke at SPS
gave me a list of fuel tank sealers and suggestion to improve my method of making things, I gather I was basically making a surf board.

Symetry, well people don't make profile gauges and check tanks so if I was happy the tank was right;-)