In this video we'll be showing you how to make this professionally finished prepreg carbon fibre airbox,

using the complex three piece split mould that we made in the previous video.

If you are new to prepreg check out our complete introduction to prepreg carbon fibre video.

In that video you'll find lots of information on the handling, processing and curing of this material.

For what we're doing today we can keep things really simple because almost everything that

we're using to produce this part comes in our prepreg carbon fibre kit starter kit.

In the kit you've got all of the consumables that you need.

You have five metres of vacuum bagging film, unperforated release film and breather cloth.

You also get high temperature silicone vacuum hose, through bag connector, two rolls of vacuum bagging gum tape

and optionally if you don't already have a pump, a composites vacuum pump.

Then of course the prepreg itself.

We have over 1.2 square metres of both the Easy-Preg surfacing layer and the Vari-Preg backing layer

This is dispatched straight from our freezers in sealed packets and stored on roll.

One of the great things about working with prepreg is how accurately and efficiently you can cut the material.

So the first thing we're going to do here is just lay masking tape on to these moulds to give us some accurate cutting templates.

This one is a very simple part to template for because we're going to laminate this is one component.

When it comes to the lower section we actually want to laminate these two while they are fastened together.

So I'm going to bolt these together now and then create the masking tape template inside there.

When deciding where to put cuts in the material you should consider both the

cosmetic appearance of the join will be and also the ease of which the part can be laminated.

In many cases this will mean locating the join in a corner on the mould.

Corners visually hide the join and also make it easier to lay up without bridging. You can transfer these

templates that you've made onto any material that you like. We're going to be using fluted

signboard as it's very to cut and fairly durable. With templates from compound shapes you will

find that they often will not easily lay flat. In these cases you should flatten them and

interpret the true shape as best as you can. With the rough templates down we've got to

consider before we cut these out whether any of them need extending or how they're going

to sit into the mould. This will be our first component into the mould. So we want this

piece

of material to be precisely cut to this line so this won't get changed. It will be cut

out at that size. However where the join is it's much better to have overlap of material

rather than a butt join. So we will extend the side panels here out by around a bout

10mm to give us that overlap. When we're looking at the top section we will be cutting this

one slightly oversize. Just to give us an extra bit of tolerance and margin for error

when we're laying it up. Before precisely cutting it down to the seam on the mould.

So these are the basic templates now and you can see roughly how they'll fit into the mould

itself. Now the other thing that we want to consider is where ever these parts of are

joining. so where that part meets that part. We'd like the weave to align. There's a simple

trick to doing that and that is to mark up the orientation of the weave on the respective

components. So again with the top section there to be in that position. We can do the

same thing and ensure that the weave along that join will line up. Before we go on to

cutting out the prepreg material itself we're going to take the opportunity to apply release

agent to the mould. Now as you may have already gathered we've produced a part from this so

its already had several applications of release agent. But it is always a good idea between

every release to apply one more application. Normal release agent, conventional release

agent such as wax and PVA don't work for prepregs due to the high temperatures that are involve.

So you really have to use chemical release agent such as Easy-Lease. Now when this part

is actually vacuum bagged some of the resin will get driven between the parting lines.

So it's equally important to get release agent on to the flanges of the mould as it is the

surface of the moulding. So we'll be applying release agent right over the surface over

here and also these areas here and here. If you've been storing your prepreg in a freezer

make sure it's fully defrosted before you unpackaged it. We need a piece of the surfacing

and a piece of the backing ply of the prepreg. The special Easy-Preg surfacing ply you can

identify because it's dry on one side. This prepreg really is the secret behind getting

a pinhole free surface finish. The backing ply is much heavier material made from 450g

cloth and that can be identified by the fact that it's got plastic covering on both sides.

You're looking to get these templates nested as tightly as you can thus avoiding waste

material. Cutting the prepreg is very straightforward as long as you've got a substantial pair

of shears. The surfacing layer being much thinner than the backing can be cut quite

easily using a pair of shears or a knife. Now we can see here how we're looking to get

the weave alignment. This is the first layer into the mould so this is the piece of material

that you see. So we're looking to ensure that our weave alignment is absolutely perfect

on these parts. With the twill fabric you get quite a distinct line running in the diagonal

across at forty five degrees to the weave. These lines here we're looking to align those

with the lines that we can see on the surface of the material. So we'll be taking the templates

and making sure at every stage that line carries through from the lines that we have marked.

The excess material that we have got here, if it's not going to be used immediately that

can be rolled back up put into a sealed bag and re-frozen. With out kit of prepreg ready

and our moulds prepared we are now ready to start the lay up. First loosely place the

material into the mould ensuring that it is accurately in position before firmly pressing

it against the surface. It is goods practise to work the material from the centre outwards.

This ensures that the material is in intimate contact with the entire mould surface. Any

air pocket or bridging of the fabric in corners must be driven out. In a cooler working environment

for intricate shapes it's sometimes advantageous to slightly warm the prepreg using a hair

dryer or a heat gun to make it tackier and more pliable. In the case of this part however

it won't be needed. The backing ply is laminated in much the same way as the surface but extra

care must be taken when placing it into the mould as repositioning can often disturb and

lift the surface ply beneath. You will also find that this heavyweight material is less

pliable and can take a little more force to manipulate. Prepreg laminating tools are often

used to aid the laminating process. These normally consist of a range of blunt instruments,

often hand shaped by the laminator from plastic or even carbon fibre. These are then used

to push, manipulate and burnish the material firmly against the mould surface. If ever

there is a fault in a final component. 9 times out of 10 it will be small pin holes in a

corner this is as a result of the material bridging. You must pay extra attention to

corners ensuring that there are no voids between the mould surface and the prepreg. With the

two plys properly laminated into the mould the excess is trimmed off with a sharp knife

blade. Ensure that the blade is kept flat and does not scratch and damage the mould

flange. You should make sure that the cut line is neat and level with the flange. This

will ensure a neat join in the part is provided. With the opposite section complete we will

now move on to the slightly more complex lay up of the lower mould tool. Starting with

the base piece of material this is laid precisely into the mould. The edges of this piece will

be the visible join on the part so accurate placement ensures a neat final finish. To

make handling easier the hole for the aperture is not cut until the piece is in place. The

hole is then simply cut with a knife. The sides pieces are then placed into the mould.

If you remember these are cut slightly larger to allow for overlap onto the first piece.

In the case of this part the overlap of around 10mm will provide a strong joint. When curing

the resin will flow around this joint making a seamless finish at the point of overlap.

To make the lay up easier in the corners I'm snipping small nicks into the material. I'm

only doing this where the material is overlapping so that it won't excessively weaken the part

or be visible on the surface. Again here I'm using the same prepreg laminating tool mentioned

earlier to ensure that this special surfacing prepreg is pressed down firmly against the

mould surface. Small snips are used again in

the corners to allow the main material to

be folded into the mould with minimal distortion. A real benefit of working with prepregs is

the way the intricate layups like this can be carefully assembled step by step with the

prepreg tacking itself into place on the mould surface and staying in position. Again the

backing layer we're laying down here is tacky enough to stick nicely to the surface layer.

We position it carefully and then apply pressure to stick it down firmly. Excess reinforcement

is easy to trim away using scissors or a knife. That's the prepreg carbon laid into both these

two parts. You can see on this one we've put the carbon completely level with the flange

there. Whereas on the other half we've left about 15mm on the top. That 15mm flap will

be folded in, but then we'll join the two together when we come to the vacuum bagging

stage. I'm going to put a few small snips into the carbon around the corner here to

allow the flaps to be folded in without creasing. We'll fold these over and give them a quick

press so that they align in to the mould and get the lid section on before they have chance

to straighten up. Now we've got these two moulds parts bolted together you can see the

extension that we left on the lower part of the section will overlap over the upper part

making a very strong bond between the two. With the layup complete we're now going to

move on to the vacuum bagging. it uses a completely conventional vacuum bagging stack so we're

using the materials that come in the kit. Starting

with the unperforated release film follow

by breather layer and then We'll put that into an envelop release bag. The purpose

of this release film is to provide a non stick impervious barrier between the prepreg material

and the breather layer which we will be adding next. Prepregs have perfectly measured resin

to fibre ratios and so we don't want the breather to absorb any resin from the laminate. Which

is why always use unperforated release film with these prepregs. Ensure the film covers

the whole surface of the part without any tight spots of bridging using some tape to

hold it in place. Don't worry about overlaps and creases as these will not have an adverse

effect on the part. Check again carefully for any bridging particularly in the corners.

So now we're onto the breather layer. Which again we're going to put in to the mould in

the same way we did the release film. The breather cloth is there to maintain air paths

through the bag. it should be positioned across the whole surface of the mould and then held

in place with some tape. To eliminate the chances of any of these sharp mould edges

or the bolts themselves puncturing the bag we're also going wrap the back of the mould

in some breather. This will offer a reasonable degree of protection. Now we're going to use

the vacuum bagging film from the kit to make an envelope bag. So a bag that all of this

goes inside and then seal it. To seal the bag you want to go slightly beyond the fold

in the film. Then lay your sealant tape flat onto the bag. Then that fold, once the backing

tape has been removed, can be doubled back on itself and will provide a perfect seal.

It makes life a lot easier at this point if you also apply the seal to the other side,

but obviously don't seal the bag up completely. Lift the whole mould and the extra breather

surrounding it into the vacuum bag. Through bag connector is the next thing, easily forgotten.

So we put one insert on the inside there. Then pinch a small amount of the bag, snip

it, place that side of the insert through the bag and then firmly tighten the two together.

Now that both the part and the through bag connector are where they should be inside

the bag peel off and seal the tape that we positioned earlier. We're now ready to pull

a vacuum. So all we need to do is take the composites vacuum pump. Connector our high

temperature silicone hose to it and then to the through bag connector. Switch the pump

on and we'll gradually pull down the bag whilst positioning it. Being such a complicated shape

it is perhaps a little difficult to see what's happening here as we first begin to pull

down the vacuum. Essentially what I'm doing is feeding all of the surplus bag inside the

mould through the aperture in the base and then pushing this surplus of bag up into the

neck of the airbox. Whilst at the same time pushing more surplus bag into the neck through

the other side As the bulk of the air is removed from the bag you'll want to periodically close

the vacuum valve to provide sufficient time to reposition the bag. It is essential that

by the time the bag starts to tighten up it has been carefully positioned and jostled

in to place so that it's properly in to all of the corners of the mould. Without any bridging

or tighter areas. You can see here where the vacuum bag that's been pushed into the neck

from the inside meets the bag that's been pushed in from the outside. We need to make

sure that there is no bridging around the outside of this area too. With the bag fully