Help Needed with Carbon Project

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#1

Hi All,

I’m new to this forum and hoping to get some advice from you guys about a little carbon project I have been working on.

I came up with a design for a car body part that I have built from GRP and now I want to make a few more for sale but in carbon. I have done a little overlaying carbon work myself before but really don’t have the time or space to make these now.

I have a GRP mould made up of the part, and asked someone to make up a few carbon prototypes for me cheaply but as the part is quite long (about 1300mm x 200mm) he struggled to get bubbles out of the piece using the wet layup method. So much so there were lines of bubbles just above the carbon fabric in quite a few areas. He tried wet layup with and without vacuum bagging but no success. The part does have a few curves and a small recessed area but I would say the part is not a complex piece.

Eventually after weeks of going back and forth I was told that he cannot make the piece using wet layup without getting bubbles and that the only way to avoid bubbles completely was to use pre-preg. I know it is very difficult to avoid bubbles completely, but I just can’t accept large patches of bubbles – it just wouldn’t sell.

As I want to keep the cost down, I’m relunctant to go down the pre-preg route if possible.

My questions are…
Is it really not possible to get a reasonably good near bubble-free finish with wet layup?
Is this something I can do myself without vacuum bagging?
Alternatively, does anyone know someone near London (preferably near North London) who can help me make these cheaply?

Many thanks if you can help! :slight_smile:

EDIT: Font size too big!

#2

Welcome to the forums,

It is possible to get a bubble free wet layup but it takes skill and practice and a lot of luck. If you want consistently good parts you’re going to have to learn vacuum bagging. You might get a bubble free part but the amount of resin is going to be too high, even for a cosmetic part. It is now a well accepted fact that some sort of consolidation force is needed to produce a quality composite, whether it be atmospheric pressure, an autoclave, or a press. There are a few members on this forum that live in the UK who might be able to help you for a price.

Also in future posts please cut down on the excessive formatting. It makes your posts difficult to read.

#3

Have you got a photo of the mould or part i my be able to help,how are you putting to resin in / on the cloth?
iam in hampshire

#4

As darren said a photo of what you are talking about would be helpful.

Is this a part with tight corners? or some odd geomatory? shouldnt be a problem getting a part without air bubbles.

Is this being made with epoxy or polyester?

I make wet layed, vac bagged parts all the time for historic racing cars without problems.

#5

Thanks for your help. I knew that we really couldn’t get away from vacuum bagging but he was trying different techniques to see if he could stop the bubbles. Do you have any advice on preventing bubbles?

Apologies for the formatting earlier, I drafted my post on an Email then copy and pasted it in - for some reason it altered the formatting.

#6

It’s alright. To make quality parts you need to push the air out, either with a vacuum or positive pressure. Even then you might run into problems with bubbles. Aerospace standard for void content is usually around 1 to 3 percent. It also takes practice with layups and experience with your products. With some resins I am able to get perfect parts everytime. Other resins need careful mixing and degassing. If you’re having trouble I would suggest reading the threads and tutorials on this website. If you need parts quickly I would advise you to contact one of the members who posted above.

#7

Here are some photos of the part I would like to have made up. It’s about 4mm thick made up carbon and glass fibre and is mainly a cosmetic part.

At the moment, the guy helping me with these still has the mould, not sure when I can pick it up as he’s the other side of town from me.

Hopefully this will give you an idea of what I am talking about. (Ignore the grey coloured piece)

#8

have you looked into infusion??

#9

I would but I don’t have the space for the equipment (at the moment). Also, I don’t have any experience with infusion. If someone could make these cheaply for me I would prefer to pay someone to do it so I can concentrate on the design work.

#10

Ok, just picked up the mould.

darren/Matvd, what are your thoughts on this having seen the photos?

#11

4mm thick!

#12

Because i’m not using a lot of carbon ply i’m having to use fibreglass to give it some rigidity. Its a cosmetic part and i didn’t want it too thin. It was supposed to be about 3mm but it ended up being 4mm with hand layup

#13

Looks like an easy enough part,

Is the gray piece your mould? without any flange around the outside?

Are you just using the glass to reduce material costs? and has that part been made with epoxy resin?

#14

No, the grey piece is not the mould. It was just a plastic mock-up I made to check the fitment. I can get a photo of the mould if it helps. The mould was simply a gelcoat/GRP mould taken of the bumper with a small flange area around – which is not flat though as it was taken from a bumper. But there was enough area around it to allow for overrun and trimming etc.

He tried using epoxy and polyester resins. But as the recessed area will be near the exhaust pipe it needed to be heat resistant (only about 110°C or so), he suggested using something called crystic resin (correct me if wrong)?

Yes, the glass was just used to reduce material costs, if you have alternative suggestions I’d be happy to consider. The glass does make it a little heavier than I wanted but it was the only material we had that was cheap and gave it some additional rigidity.

Where are you based? I’m in North London? Your website doesn’t seem to be working.

#15

Here’s a quick photo of the mould.

#16

Im based in Norfolk next to the snetterton race track. Not sure what has happened to my website, some sort of server problem, but thankyou for making me aware of it.

I would think that wet lay with epoxy resin vac bagged shouldnt be a problem with this part.

#17

Web Site is back working now, my contact details are on there.

#18

Thanks, I’ve just sent you an Email.