Hi all, 

I'm just venturing into the more complex shapes of CF components and have set myself the task of making some CF Velocity Stacks/Trumpets for my kit car?


A friend has kindly created a 3D printer file for me to print as a inner mould but I wondered if there was a better way to do this.



Mainly, could this be done with a single mould and secondly as I would be wet laying, how would I vacuum bag this?

Many thanks in advance, next stage would be to add a CF flange to the bottom...

CeeBee

That's not a super easy thing to make with two finished sides.  The inside mold you show in the drawing could be printed and you could wet-bag a carbon layup over it but it would be a pain to get it nice and not to destroy the mold.  I've found 3D printed molds are very easy to destroy!  Since it doesn't need to be hollow down the middle (I think) you could print in some holes and space for a bolt or three to run through to keep the mold from coming apart - assuming FDM print with layers.  

One thing to try would be braided sleeve material which you could slide over the mold and wet out in place - you'd probably need a few layers so could be a challenge - but it would mean no seams in the carbon and an even weave look. 

If this is only 50mm diameter or so on the small end it could be hard to get multiple pieces or carbon to work nicely.  For production work volumes a metal mold and some pre-preg would be the tidy solution - maybe with a caul plate or contra-mold for the B-side.  For just a few you are probably fine with a 3D printed mold but it will take some work and probably some re-do's.  Which side is the most visually important?  

I would also suggest overbuilding the flange bit at the bottom/wide end so you have a way to grab the part for demolding.  Or maybe laminating over the top and leaving a hole through the middle to push the part off with a dowel or punch.

If you're familiar with vacuum bagging simpler parts you should be ok - just expect there to be a learning curve - and please report back with your results!

I wonder if you could do a split mold and use pre-preg like this example:
split mold video from easy composites