How to Make a Carbon Fiber Car Bonnet/Hood – Part 1/3


Hello and welcome to this Easy Composites
video tutorial. In this series which is probably the most ambitious we’ll ever take on we’re
going to be answering the question that we get asked more often than any other, which
is how to make you’re own carbon fibre vehicle panels like this car bonnet that you see here.
In the tutorial we’re going to be showing you every single step along the way including
making the mould, making the parts, bonding the parts together, trimming and finishing
to enable you to make your own incredibly light, incredibly strong perfectly finished
carbon fibre panels. We really hope you enjoy it. The first step in our process is to take
this original steel bonnet which we’re using as our pattern. We’re going to add barriers
all the way around the outside of it so that when we make our mould we actually created
a mould with a flange on, and that flange will add stiffness to the mould and it will
also give us plenty of opportunity to position the bagging consumables and things for the
resin process. Before we actually apply any barriers to this part we’re just going to
take the opportunity to put down a full background layer of release agent. We’re using Easy Lease
which is a chemical release agent and of cause this is what’s going to stop the gel coat
from sticking to the part but while we’ve got the bonnet in this state it’s much easier
to ensure that we’ve got everywhere covered and then we’ll probably do another application
later on. Making barriers can be tricky. The technique that we’ve developed is to use corrugated
signboard for the barriers themselves and the bond those to the underside of the part
using hot melt glue. So the first thing to do is to use masking tape to actually make
a template around the edge of the part and then we’ll transfer that onto the signboard
and cut the barriers themselves. So with the masking tape all the way around the edge of
the part it’s a case of just marking up where we’re actually going to make the barrier pieces
in separate sections and we also at the same time just draw on the angle that we’re going
to cut the barrier sections at and finally number them so we can identify them. So we’re
going to have a cut line here and a cut line coming off at this angle here. Then this will
all be one piece and we’ll have cut lines on the barrier about there. The masking tape
comes off the part extremely easily. So we’re just going to start it off and then cut it
into the parts that we’ve identified, being careful not to rip the tape. So we’re transferring
this line here onto the board. We know the angles that we want to make the barriers at.
Once we’ve marked out all these templates we’re just going to cut them out with a sharp
knife and then position them around the outside of
the part. we’re working on the underside of
the bonnet now where we’re going to be positioning this barrier. Now the way we’re going to do
that is we’re going to apply masking tape to the edge on the underside of the bonnet
here and then we’re going to be using hot melt glue on the masking tape and then on
the barrier. the reason for the masking tape is so that this barrier is quite easy to remove
when we’re done with the process. So we can get started with that with the masking tape.
We’ve got masking tape all the way along this top edge so now it’s time to use hot melt
glue gun we’re going to just put a bead of glue all the way along the top edge and then
stick the barrier to it. We’ve now flipped this bonnet over just before we do the wax
we’re actually going to use a release tape to actually just seal these joins, or a breaker
tape and that’s just going to prevent again any of the gel coat from running down into
the gap. So we just take the tape and tape the seam and because it’s a release tape the
resin and the gel coat won’t stick to it. So the next step is to us a yellow filleting
wax to actually create a bead all the way around the edge between the bonnet onto the
flange and what that will do is stops the gel coat from running under and locking in
and also gives us a nice smooth transition so that when we’ve got the mould the parts
themselves are going to release nicely and they’re not going to get caught up or mechanically
locked on this edge. So we’ve put the filleting wax all the way around the outside now and
you can see from this close up what we want to do is always be sure that when you put
the wax down you’ve got what’s called a draft angle and that’s going to mean that when we
remove the part of separate the part and the mould that there’s not going to be a mechanically
lock. We’re now ready to put the proper coat of release agent onto the bonnet and we’re
going to apply two coats of the Easy Lease all the way over the surface of the panel.
Now the filleting wax doesn’t requite a release agent and in fact will actually get dragged
off by the release agent if we’re not careful so we’re not going to apply any release agent
to the wax. We are going to apply the release agent onto the barrier itself just in case
there’s any contamination. It is made from polypropylene so it shouldn’t stick but just
in case it does we’re going to give it a coat over as well. We’ve now left this a good half
an hour to fully dry off and we’re actually going to apply two coats of wax all the way
over the top of this the steel bonnet part. Now usually we wouldn’t use a wax on top of
a release agent. A chemical release agent generally works on its own however in the
case of going from a pattern to the mould itself we want to be absolutely sure that
we’re not going to have any problems with the release and so having the chemical release
agent and the wax although it’s a slightly unusual combination is going to ensure that
we do have no release problems. We’re now buffing off the wax having left it about five
or ten minutes and you just really want the lightest possible pressure when you’re doing
this just using a micro fibre cloth here and just skimming over the surface and you can
see the shine start to emerge. Right so we’ve now left the wax to fully harden off which
is roundabout half an hour or something like that and so it’s actually time to make the
mould itself. So we’re going to be using a very versatile tooling system called Uni-Mould
and the Uni-Mould system comprises a tooling gel coat which is a vinylester tooling coat.
Now the reason we’re using vinylester is that that’s actually compatible with polyester
resin, vinylester resin but most importantly for us epoxy resin and it will guarantee an
excellent release of the parts out of the mould which you wouldn’t get with a normal
polyester gel coat. The Uni-Mould system then uses a coupling coat which is reinforced coupling
coat we actually add a lightweight chopped strand mat in with that which forms the connection
between the tooling gel and then the tooling resin itself. Applying the gel coat now we
can do this in either two thin coats or one thicker coat. We’d be targeting in a single
thick coat of a roundabout 0.8 mm. Now for a bonnet this size we’re looking at mixing
up a roundabout 700 grams of gel coat if you mix up too little and you come up short you
can always mix up some more. We’re using normal MEKP catalyst and a ratio of about 1.5 to
2 percent. So for 700 grams of the gel coat that would obviously be 14 grams at 2 percent
of the catalyst. Applying the gel coat is totally straightforward covering it and we’re
going for that approximately 1 mm which is a reasonably thick application. We’ve now
allowed this gel coat to cure to the right point. It’s certainly very much firmed up
but it’s still got a very slight level of tack which is the right point for a gel coat.
So in the Un-Mould system it’s now time to add the coupling coat. As we say we’ve got
a light chopped strand mat, we’re using a 225 gram here. This is really as heavy as
you would want to go at the coupling coat stage, you could go lighter and we’re going
to be wetting this through with the coupling coat. Again this is catalysed at a ratio of
about 1.5 to 2 percent we’re going to be catalysing it about 2 percent and we’re going to use
a full kilo on this layer. When the coupling coat has been fully catalysed it does actually
change to a darker colour so you can tell it’s ready to go. Now when you’re working
with he coupling coat it’s just like any chopped strand laminating so you apply the resin to
the part first and then drop the glass mat down onto the resin and then wet it through
from above. The light chopped strand provides reinforcement at this early stage but because
its a light mat it’s very easy to get it down into the contours of a mould which ensures
that you’re not going to have any voids between the gel coat and the main tooling reinforcement
and the coupling coat itself chemically is designed to act as an interface between this
vinylester tooling gel coat and the tooling resin itself. We’ve now allowed this coupling
coat to cure in our case its taken around three hours and it’s very much firm to the
touch but it got a slight tack and that’s the right point for us to go on with the main
reinforcement. Now because we’re using the Uni-Mould tooling system we’re going to be
putting down all of the reinforcement and the resin in one hit. The Uni-Mould tooling
resin is a filled resin system so it’s very important to thoroughly mix up the contents
and we’ll also give it a quick stir to make sure that any sediment or fillers are thoroughly
mixed in to the resin. With the resin catalysed at between 1 and 2 percent, we’ve used 2 percent
because it’s only a small mould we’re then going to apply the resin all the way over
the surface and start building up this chopped strand mat. So we want to work reasonably
quickly and get it all down in one hit. We’ve now allowed this to cure fully overnight as
you can see the colour of the mould has changed to a lighter shade indicating that the exotherm
has taken place and so we’re going to turn the mould over and without removing the bonnet
we’re going to look at making the moulding for the inner skin. Okay so we’re now going
to remove the temporary barriers that we put in place. And you can see the why we signboard
its released perfectly from the tooling gel coat. we’re going to be using the flange from
the upper mould as the flange for the lower mould and so what we’re going to do is leave
most of this filleting wax in place but we’re just going to ensure that it’s nice and smooth
so that its acts again as a fillet between the flange and the inner mould that we’re
going to make. So we’re looking at the underside of the bonnet now. We’ve got lots of holes
as you can see that have been cut out, die stamped out of this inner skin we need to
blank all of these of which we’ll be using release tape for and we’ve also got these
studs here that were for the hinge mechanism and the latch at the front. Now because we’re
happy to sacrifice the bonnet in this case we’re going to grind these off and again grind
the latch mechanism off. If you didn’t want to sacrifice the bonnet and you want to keep
it useable then you could blank these off using plasticize or something similar and
then make the mould around them but for simplicity we’re just going to grind them off. So applying
the release tape to mask off these holes on the underside of the bonnet. We just pull
the tape tight over the hole and press it down firmly. So where we’ve ground off this
latch mechanism we’re going to tape all the way over this using the release tape. And
the tape should be sufficiently strong that we won’t need any other reinforcement over
that area. So we’re applying the Easy Lease chemical release agent all the way over the
surface of the inside of this part and very importantly this time round on the flanges
as well. We’ll be applying two applications of the chemical release agent and then we’ll
be following up with two coats of wax making sure on this occasion that we thoroughly wax
the flange. Where you can see the upper moulding meeting the lower moulding and we’ve got this
gap here we need to thoroughly fill that with the wax fillet to prevent the tooling coat
from running under there and sticking. So we just put in a large bead of wax and then
smooth it out in just the way we’ve been doing elsewhere. So if we just take a quick tour
now of what we’ve done before we put the gel coat on. We’ve got release tape over all of
the catch mechanisms we’ve got any interior holes we’ve filled with release tape and again
we’ve cut those to be nice and neat. On these areas where we’ve got a bit of undercut on
the actual steel of the bonnet we’ve completely filled that with filleting wax as we did with
this awkward corner. And you can also see how we finished that middle edge. Okay so
we’ve just mixed up a new batch of the tooling gel coat and we’re just going to apply this
all the way over the surface of the inside of this mould just like we did on the top
mould. Again we’re going for that target 0.8 mm thickness which is a reasonably thick brush
application. now that the gel has cured we’re just going to put down another coupling coat
exactly as we did before. here again we’re using the 225 gram glass but another excellent
option for the coupling coat is something even lighter like a couple of layers of an
80 gram. So the coupling coat has no cured of and it’s time for the main reinforcement
again. Just like before we’ll be applying all of the reinforcement and the tooling resin
in one session. We’ll be using four layers of the 450 gram chopped strand mat. So that’s
the underside of this mould finished so we’ll allow this to cure fully overnight and then
tomorrow we’ll be trimming these and separating them. This mould has fully cured now so we’ve
marked up a trim line all the way round the edge equally spaced to where we know the bonnet
comes to. And so now we’re going to trim them apart to separate them. We’re going to be
using a jigsaw cutter to trim the two moulds and we’re using a permagrit blade which is
a tungsten carbide blade in the jigsaw. With the mould fully trimmed it’s now time to some
extent for the moment of truth and what we’re going to do is separate the upper and lowers
moulds. So to do it we’re going to be using a chisel and trying to insert it between the
two layers of gel coat and then just tapping that in with a hammer, I think we can hear
the moulds releasing. So we’re just going to insert lollypop sticks now. That’s sounding
good. So that’s our upper bonnet moulding done now and it’s just time to remove the
bonnet itself from this lower tool. We’ll be looking at doing this underside moulding
first because it’s actually slightly more complicated than the upper moulding. So the
first things that we’ll do are pretty self explanatory we’ll strip off any of the filleting
wax that’s on the underside of the moulding. We’ll also be looking at taking off any of
the release tape. And finally if there’s any blemishes such as this one here then we’ll
just be filling some gel into those areas. You’ll fine that a chemical mould cleaner
like this will quickly and easily strip off the filleting wax and any other contamination
from the mould surface. So this area that you can see here, I think the paint actually
wrinkled up on the underside of the bonnet and it’s left this blemish here so what we’re
going to do is chisel out all of the paint and some of the gel coat so that we’ve got
some fresh material and then we’re going to put some new tooling gel coat into this blemished
area and sand it smooth. So to make a repair like this what we do is we mix up just a small
amount of the Uni-Mould tooling gel coat a few drops of wax additive and the wax additive
prevents the gel coat from staying tacky on the surface where it comes into contact with
air like a gel coat would normally do. Once the gel coat has hardened up and you can see
that the wax additive that we included has meant that there’s no tackiness here then
we can start wet sanding and flatting. So we’ve flatted this out nicely now using the
wet and dry paper, we’re just finishing it off with a 1200 grit before we go on and use
polishing compound which we can either apply by hand or as we’re going to do using a polishing
wheel. Although both of these tools are now pretty much ready to use as they are to give
this a real professional finish what we’re going to do on this top mould is give this
a wet flat all over with a 1200 grit and then we’re going to polish it all over using an
intermediate polishing compound like this Mirka T10. The reason for wanting to give
it that flat on the surface is if you just catch the reflection here of the light you
can just see a very very slightly texture to the surface and that’s partly print through
from the chopped strand mat underneath and other just surface imperfections on the original
bonnet. We’ve now polished both of these moulds up to a high standard and so that actually
concludes the fist part in this video series. In the next instalment we’re going to be looking
at using both of these moulds to produce the parts themselves using the resin infusion
process. I really hope that you’ve enjoyed this video. For more information or to purchase
any of the products that we’ve used in this video please visit our website easycomposites.co.uk.