Help with carbon doors

General Composites Discussions Composites Talk
#1

Im making carbon lower doors for a side by side. Im fairly new at composites

My parts are not turning out very well, and do not appear to be getting sucked down into every corner of the mold.

3k 270gsm carbon
wetted out (with Adtech 820 resin/slow hardener) in between two sheets of plastic and epoxy squeegeed with a bondo spreader
Freekote 770 mold release
Fiberglass mold with gelcoat from ACP

Process:
Treat mold with release
Lay in pre wetted carbon
Lay in peel ply cut into strips
Lay in breather cotton in strips
Put in vacuum bag - green stretchlon film
Pull vacuum and push everything into corners and cracks
Demold
Be disappointed

I like the matte carbon look for these doors so I cant hide my few flaws with clear.

Any help is greatly appreciated!

Thanks!

#2

Thats a pretty good result for a composite newbe. You can fix it with clear and than use a matt clear for the finish layer.

#3

Thanks.

I put in ALOT of time on these pieces.

Id like to avoid spraying anything on the part and just figure out what Im doing wrong.

What am I doing wrong?

An old guy with no composite experience suggested I make a male mold to stick inside of my current mold to asure the carbon gets forced down into every crack and corner of the mold.

Hows that sound?

#4

Why are you peel plying the back ?
You don’t appear to be using a release film ? P3 halar should solve your problems as at the moment your pulling too much resin out
Lot easier than spending hrs clear coating

#5

Thanks F1rob

I dont know exactly why Im using peel ply…Im new to this.

I put cotton breather material on the part so im told I need to use peel ply to keep it from sticking.

I have perforated release film. I cant remember off the top of my head the size of the holes or the spacing.

My first thoughts we that I was sucking too much resin out. So can I use this release film and still put breather material on top? I forsee it sticking everywhere there’s a hole in the release film.

I agree. All this time trying to fix a part post mold is rediculous and deff tests a persons patience.

I might add…

Due to me being unable to get the carbon to toutch in every spot, I have been putting 1 layer of carbon in, then vacuum bagging

Then i add 3mm coremat and another layer, and re-bag.

I would love to be able to do it all in one process.

Thanks again F1rob…I will use release film with holes in it next time and see what happens.

#6

P3 has tiny holes,you might get a few tiny breather fibres stick but quick rub with 180 grit looses them
Breather over all of your release
You should be able to do them in one hit.peel ply is used when you do 2 shot and you want a rough surface to stick to
If you still want to do 2 shot use the peel but p3 an blanket on top of that
30 years ago when there weren’t the thin resins about that make resin infusion possible for the home laminator nearly everything was wet lay vac an with a little practice you can get parts as good as or better than infusion
Not bad for a 1st try thou

#7

A part made by wet layup better than infusion? No chance. May be a worse i fusion compared to a good wet layup.
The question is if you vac bag your part why not infusion?

#8

I tried infusion…but I couldnt even do a flat part. The resin just ran over the top of the part and wouldn’t wet everything out

#9

Time,money,convenience to name a few !
Depends what you want to do, if I was doing lots of small parts for production would cast silicone patterns an mount on a board,put my flow paths in an make a mould for infusion
If your a guy in a garage doing a set of door you can do it wet lay vac and get the results you want
You can get those results with infusion but takes more outlay and time

#10

Well,the goal is to make about 10 sets for now.

#11

I would change to infusion! Will give you a perfect quality and will not take more time. If you need help contact me.

#12

Worth mentioning that a raw carbon part will discolour over time as epoxy is not UV stable, only an issue for parts subject to direct sunlight which I suspect your doors will be.

If you are bagging the parts then I think Resin infusion is definitely the way to go imo

#13

Do you have a picture of the setup you used? The resin almost certainly ran over the top due to the setup with the flowmesh.

#14

For UV stability there are additives that stop yellowing. And yes they work perfect!

#15

Additives?

#16

My adtech 820 resin says its UV stable.

Here is a link with some pics of my infusion set up.

http://www.compositescentral.com/showthread.php?t=10219

Spriral tubing running the width of the part on both resin and vacuum sides

First attempt the resin ran out of the ends of the spiral tubing and straight down both sides, never wetting out the middle at all.

Then I covered the ends with tape and it helped. Although the resin did not wet out the carbon completely and just ran across the top of the part.

The part was only about 1ft by 1ft square with very slight angles.

#17

Mti hose is the answer and your friend. I’ve been using nothing but the Mti hose and adtech 820 for a few years now.

#18

Is that the non resin permiable hose?

It let’s air thru but stops the resin?

And then your feed line goes directly on the part?

Can I then get away with not having to worry about a catch pot?

Thanks

#19

you need to plan the resin path, spiral tubing to flow across the path IF required on smaller parts I rarely use spiral tube, but you do need an infusion mesh over the part… i usually leave the exit path without any mesh to encourage it to wet everything else out before exiting.

#20

Thats how I would do it, red is resin inlet (I would use Blade Runner Infusion line) and blue is air out (I would use MTI hose).
Flow media all over the part but let the flow media end about 2cm before the MTI hose.
Seal 1st bag on mould flange and second bag envelope bag, than you are save.

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