Guys,

I have had an unexpected project come up. I had a little bump in my track car last week. Luckily, it has only caused damage to the front bumper and front splitter. Other than that, the car is A-OK. 

So I have decided that i will make a composite front bumper. 

Thinking out loud:

The style of the bumper is very sporty and aggressive with sharp edges but fortunately there will be no issues with mechanical lock so I will be able to make a single piece mould that should release with a little tug tug. When laying the first layer of 2x2 CF fabric I think it will be next to impossible to avoid creasing and folding to the cloth. Is there a solution for this?

Could I stencil out individual pieces of cloth and align them together with a small overlap or will that translate into the finish piece.
Or the other potential option is the make a forged piece.


Please let me know your thoughts.

Thank you.

Cutting and jointing individual pieces of fabric is indeed the way to go when trying to overcome curves and angles that would, otherwise, cause a large single piece to distort

With care taken to place the joints in the lowest/highest points of corners and good matching-up of the joined pieces everything can look really good. 

You just need to think about what pieces would benefit from being cut separately and make up some templates using something like masking tape as demonstrated in some of the EC tutorial videos. A mist of spray tack over cut lines can help keep your cuts neat, along with using something like an Olfa roller cutter if using shears is tricky on some pieces

Once you've placed your cut sections, you can then drape your main section of fabric and work out where you might need to make some relief cuts to allow it to lay as flat as possible and slightly overlap the sections already placed in the mould.

On something like a recessed section where you might have placed some pieces to cover the entirety of the recess, you could make a couple of cuts in a cross shape up to the edge of the recess to allow the triangular flaps created to lay down neatly without pulling on the surrounding fabric. It can be quite fiddly work, but using soft chalk can help with marking where you might need to make cuts.

Rather than make lots of cuts in one go before trying to lay down the main section, you could start in the centre and work your way outwards, using light mists of spray tack to keep everything in place as you go. 

On work such as this, I'd certainly recommend using the more expensive 240g twill, as this is usually much more stable and less likely to fray and fall apart when handled, assuming that you're looking to use a process and fabric other than pre-preg.  

Bang. On. ^^

Thank you for your reply, this is helpful.

And yes, with the above technique, my main concern was as you say, cutting stencilled pieces of CF cloth and it fraying the the point where its impossible to handle. Normally, with a single piece of carbon fibre cloth, I use masking tape to mark my cutting line a cut along it. But of course you cannot do that if you have separate pieces as the masking tape would be incorporated into the final piece.

I cannot use prepreg as I don't not have access to a large oven.

Thanks.