Vacuum Bagging Carbon Fiber On $50

!±8± Vacuum Bagging Carbon Fiber On

Tools Needed:

Cashew/Paint Can

2" Aluminum Stock

1/4" Copper Pipe

2 1/8 NPT to Barb Fittings

Charcoal

Vacuum Hose

Zip Ties

Misc Bolts

Glad ForceFlex Bags

Polyester Fill

Duct Tape

Sponge

Resin System

Composite Mat

Mold

Vacuum Pump

Because no one likes the the fiberglass parts on ebay, and you want something more unique than just a cheap part wrapped in graphite, you have decided to make your own parts. But where do you start? Vacuum bagging equipment is somewhat specialized, and expensive. Thats what makes this how-to unique. Instead of using specific equipment, I have in the shop, I will do this how-to assuming you have nothing to work with. For only dollars I will show you how to build a basic vacuum bagging system with common items. All you have to supply is the resin and fiber. While some elements of this how-to are not the best professional practices, it will get the job done. Keep in mind that this guide is intended for the DIY'er on a budget and requires no hard to obtain items.

The core of any system is of course the pump and the bag. The vacuum pump can be sourced off ebay or any auto store. The same pumps used to suck the oil out of dipsticks will also work for our task here. These vacuum pumps will draw decent vacuum with enough flow for small to medium vacuum projects. With shipping/tax you can usually get these for ~ . If you are only going to do a few small parts, you can run the pump directly to the bag. However, if you want the pump to have a longer service life, or you opt for a more expensive pump and wish to protect it, you will need a resin/VOC trap. VOCs, or volatile organic compounds are a byproduct of the resin curing. Pumping them through your motor is not a good idea. This is why you need to construct a scrubber.

The core of your scrubber will be a paint or cashew can. I find the shorter cashew cans resist imploding better, but any metal can with a metal lid will work. If you have it, you can even use PVC pipe. The first thing to do is reinforce the lid so you can add vacuum ports. Cut a 2" section off your piece of aluminum stock. Then coat the back of the piece with epoxy. Before it can dry bolt it in place with 4 small bolts in the corners. A dab of epoxy on each bolt will assure there are no leaks.

Allow the epoxy to cure at least 8 hours. With the epoxy cured you can now drill 2 holes and chase them with a 1/8 NPT tap. Now install the two fittings. Pipe-dope will make sure there are no leaks, but you can also use the same epoxy you used in the earlier step. Take a 16" piece of copper pipe and drill several very small holes in the last 10" of it. Then crimp the bottom end shut and bend it into a coil. You do not need to worry about the smoothness of the bends as long as you don't kink it shut.

Now put the copper coil into the can and fill the can ~2/3 with charcoal pellets. You can find charcoal at any aquarium store for a few dollars. Now connect a short section of rubber hose between the copper coil and and the barb. I used safety wire to hold it in place but you can also use zipties. With everything connected you can now close up the can.

Before going into any detail lets cover the basics on what we have done and what we will do. So far we have created a VOC scrubber to help protect our pump. In the next steps we will connect the pump to the filter, and finally our scrubber to the bag with the mold and materials inside.

You do not have to use glass or steel stock for the base of your bag, but it makes it easier. If you are not using a rigid bottom just make sure you add enough pleats so your bag does not bunch around the mold.

Traditionally a PVA bag would be used. But since you cannot buy PVA just anywhere, we are using polyethylene. Glad ForceFlex trash bags are 100% polyethylene and are available pretty much anywhere. Using duct or flash tape, tape the the bag down to 3 sides of your base. Leave one side open so you can add the molds and material later. Now is a good time to cut a small hole in the bag and insert the vacuum hose from the scrubber. Tape the hose in place and insure there are no leaks. If everything is correct, you should be able to fold the bag shut and turn on the bump. Within a few seconds the bag should empty. If the bag does not empty you have a leak that needs to be tracked down and corrected.

Now coat your mold with mold release. If you do not have any mold release, lay a piece of polyethylene across the mold.

Now add 1 layer of your mat with enough extra to stick out at least 6mm from the mold. Completely wet out the first layer with whatever resin you decided to use. Because you have several additional steps to complete still, I suggest potting your resin for at least 11 minutes. Now lay one more layer of mat onto the wet resin.

To make removal easier I suggest laying another piece of polyethylene over the wet mat. Before doing this though, poke 2-3 holes per inch in the polyethylene to allow resin to be pulled through. The final layer is a layer of polyester fill. Aquarium stores also sell this for a dollar or two. This layer assure, that all the details of the mold are preserved, and that excess resin is wicked away.

The mold and material are now ready to go in the bag. Make sure you do not knock the mat and resin off the mold onto the top of the bag.

Because we are not using the vacuum bag specific connectors, the bag will want to suck to the hose end and stop the pump from drawing down the entire bag. The easy fix for this is fold a sponge or a wad of paper towels over the hose end. The pump will have no problem drawing through the sponge which will act as a resin trap to catch any excess resin.

You should leave the pump on at least long enough to allow the resin to set. During this time check from time to time for leaks. Should you locate any, tape will usually seal them up.

Once the resin is set you can turn off the pump and cut open the bag. If everything went as planned, all the layers should peel apart easily.

You may have excess resin around the two ends. This can be removed in a few seconds with sanding. Most parts will need some touch up sanding after coming out of the mold which will leave them with a semi-gloss look. Should you desire a high gloss finish, it can be achieved with a single coat of acrylic clear.