Talk Composites - The Forum for Advanced Composites

A bit of a problem

http://www.talkcomposites.com/Topic28591.aspx

By Furrari - 7/19/2018 1:00:06 PM

Although I’m in the middle of three jobs already, I’m thinking about the next job.

I have a Ferrari California replica based on a Merc SL500. It has a boot lid liner made of a compressed fibre material with a carpeted face. To match the rest of the boot interior I want to replace it with a CF panel. I thought of using some sticks to make a geodetic support on the carpet side so I can take the cover off without it loosing its shape. Covering the compressed fibre with something like packing tape or aluminium foil then layers of vacuum bag, separation ply and finally peel ply, so nothing should stick too well. I can then make a mould off the back of the liner, which should have a reasonable finish off the fibrous side and I can refinish this if I need to. Then do a CF vacuum ( envelope) baging part in the usual way. This can be fixed to the underside of the boot lid in some way. ( double sided tape with a couple of locating self tappers maybe.). I need to keep the weight down to save overloading the motors that work the convertable part of the boot lid.

Has anybody done anything like this before or has any ideas how to do it or anything I need to be aware of.

Mick
By Fasta - 7/26/2018 9:07:32 PM

 
Steve Broad - 7/26/2018 8:24:16 PM
 
Fasta - 7/26/2018 11:56:45 AM
 
Steve Broad - 7/26/2018 9:41:19 AM
 
Fasta - 7/26/2018 8:16:22 AM
 
drippy - 7/24/2018 6:30:21 PM
 
Fasta - 7/23/2018 3:52:08 PM
I have done a similar job to make new carbon boot interior for a Subaru.
To do these ones I removed the panels and coated the carpet with a thick type sandable polyester resin and sanded it smooth so that I could mould the new carbon skins directly over the old shapes and release them away after. 
Then the new parts also needed resin coating etc to get the nice finish.

Click To Enlarge
Click To Enlarge

How did you get it to keep it's shape when making the mold? Was the resin you used solid enough to keep it's shape? Did it have a form of OEM cardboard that helped?

It had some stiffness to begin with and the resin coating just made it stiffer. The parts I made off them were a bit too stiff with 200g carbon cloth, 300g glass cloth and another 200g carbon cloth. In hindsight I might consider just a 165g glass and a 200g carbon. This will keep the new part more flexible so it can flex easy to correct any error in the original mould. To make the parts in this male mould one off technique is a bit of an art compared to a mould but making proper moulds is of course very time consuming and too expensive for the customer.

Why are you mixing carbon and fibreglass?

https://www.youtube.com/watch?v=j7bQYEt_qtU&t=5s

In the video he is really only referring to proper loaded structures like an actual race car wing or yacht mast for example. For a car interior part that is just cosmetic there is literally no loads involved and so nothing will ever come near breaking. I am just saving some cost on carbon fibre.

Mixing glass and carbon using pre pregs is another story and can create distorted parts different to your moulds.

Fair comment, but you mentioned using fibreglass to improve it's flexibility. The flexibility is dictated by the carbon, not the fibreglass :-)

Relative to my original parts (200g cf, 300g glass, 200g cf) mentioned, in future I would have removed one layer of carbon and would use a lighter fibreglass (165g glass, 200g cf), it's basically just thinner and more flexible. The thickness makes a difference too.