Vacuum Bagging Questions

General Composites Discussions Equipment Talk
#1

Hey guys,

New to the forums and have been doing a lot of reading and researching.

I’ve been playing around with wet-layups of composites by hand but now am ready to move into the vacuum bagging world.

So my setup so far…

Robinair 10CFM Vacuum Pump
CatchCan
Mini Fan to cool Pump
Robinair vacuum pump oil
Hoses/fittings
Tacky tape
Painters 2mil drop cloth for bags
Duct Tape
Breather
Perforated plastic
Nylon peel ply
MAX CLR Epoxy Resin system from Ebay

I want to be using my setup for car applications.

So far I want to just lay stock parts over with real carbon fiber.

The way I am setting up the bags is from bottom to top is:

Bag
Stock Car Part
Couple Layers of Carbon Fiber
Nylon PeelPLy
Perforated plastic
Bag

Is this correct? Also when I do a vacuum pull how do I achieve a nice glossy finish? I’ve done a couple of practice parts with the vacuum but I get very low resin/epoxy percentages in my CF due to the vacuum.

Any help or advice would be greatly appreciated.

Thanks

#2

if i were you i wouldn’t bag an overlay. the only time i have ever bagged an overlay was when it was to complex and the fabric i was using was way to stiff(18-19oz if i remember right). what i would do id build a simple flat panel and then work your way up from there. i would start learning how to build molds also. start off with simple easy to bag shape then move to more complex ones. just my 2 cents

#3

Could someone direct me to a step by step instructions on how to do what drifterificfc3s said.

A panel is straight forward with the wet lay up and no bag, but is it any different with a bag?

My whole purpose of doing vacuum bagging was to do complex shapes but I want nice products and finishes too. :slight_smile:

#4

The only way to get the smooth surface is having a quality mold with a perfect surface.

Otherwise, just PUR clear coat it after overlaying.

#5

whats “PUR” and is there a specific clear coat? What prep work needs to be done?

I just tried to do some small pieces with overlay and I basically get a strong low resin content carbon fiber overlay. Do I primer it? or sand it down at that point to make a smooth surface or should I just take it to a paint shop and have them shoot it?

#6

Automotive polyurethane clear coat.

Or try pouring PER clear casting or epoxy table coating on top of it…

#7

How do i get my parts to look like this guys :confused: :confused: :confused:

http://forum.e46fanatics.com/showthread.php?t=487566

HE’S SO GOOD AT IT!!! His work is unbelievable. :eek:

#8

It’s not THAT hard :wink:
Just laminate the fibre over the part, some peelply over it, sand it smooth whitout going trough the fibre. clearcoat. (and sand, and clearcoat, etc, untill your happy or done with it :wink: )

#9

That type of work requires more time than knowledge or talent. Basicly at a level of arts and crafts. Difference being the materials are expensive and can cause cancer.

#10

what do u mean by laminate? the peel ply i used left a dry carbon look when I just pulled a test part with small little hexes that left the same impression on the carbon fiber. How do I make it smooth and gloss straight out of the bag? I don’t mind sanding it smooth afterwards.

#11

the only reason to use peel ply is if you want to continue adding layers, or glue something on that surface, thats why you need it to be rough extured. if you want a shiny surface, you just use the perforated nylon. if you wanna bag overlays its fine, but bear in mind that wherever the bag has pleats, its gonna leave high spots of resin which are gonna be a bitch to sand.

#12

ahhh… now I see… its it better to cut up strips of the perf nylon and then bag to rid myself of those pleats?

also after the vacuum… and the part comes out… it wont have the shiny 3D effect due to the removal of the resin with the vacuum so I would have to do a wet lay up over that again correct? :confused:

#13

visouz I never vacuum bag overlay parts. The pressure can and will distort the shape of the part, the resin cures, and you are left with one mis-shaped part.

If you are overlaying and can at all do it… use clear polyester resin like surfboard resin. It cures fast which is good for overlay work. Epoxy is good too, but you end up having to wait long periods of time in between sanding. Polyester will set up and be sandable within several hours. I’m using clear epoxy b/c the odor and neighbors i don’t want to upset too much.

Try to stay away from general purpose or iso polyester resin for overlay work as it is amber-brown and can cause the c/f to look brown instead of black. Clear polyester surfboard resin is the ticket if you can find it.

#14

Plus the surfboard PER has surfacing agent (liquid wax) to aide in sanding and polishing.

#15

could i clear coat it afterwards and such to give it the nice 3D effect? would it turn yellow in the sun?

#16

Yes of course you can, although it has to be said that not all surfboard resins are wax free, the Silmar stuff isn’t - you have to buy a seperate wax additive for it otherwise it will remain tacky on the surface.

#17

…and you will have to use a solvent or surface cleaner to remove all wax residue prior to clear painting the part.

I have used PVA liquid to keep the air away from curing polyester resin. Same effect as a wax, but the PVA you spray on after the final coat of resin. PVA has to be washed off with water.

If you have ever used bondo body filler or similar body filler it has the same issue… even after the bondo cures it has a tacky surface that is difficult to sand. Bondo and it’s competitors have polyester resin in them.

#18

/\ /\ /\ very great points! /\ /\ /:slight_smile: