Carbon Fiber Bodywork

I put the second layer of fabric down performing the same proceedure, then placed the core material, which is 2mm thick. I don't need to be concerned about the amount of resin, since the vacuum bagging proceedure will remove any excess resin. Even still, I was conservative with the epoxy out of habit :huh: I spread a thin layer of resin on the foam before placement as well as on top.

I layed the last two layers of fiberglass in the same mannor as the first, pouring the epoxy resin over the fabric and working it around with the squeege. I didn't really find much info on the specific steps when placing a core material in a laminate, so I was winging it here. After finishing the laminate, I noticed air pockets under the fabric along the core layer. I really didn't think anything of it. I figuered that the vacuum operations would remove remove any and all air from the laminate, and the fiberglass would conform nice and tight to the core. More on that later- I then placed a sheet of perforated release ply over the layup. This will allow the excess resin to plead through to the bleader fabric, but leave a smooth finish on the part as the perforations are every 1/4"

Then I layed out the sealing tape on the aluminum plate. I quickly learned that this is incorrect, unfortunately after the fact I folded up some of the fabric store bleeder (important tip- have all your materials precut and ready for the layup. I forgot about the bleeder fabric, and had to cut it at the last minute. Not what you want to be doing when working with a perishable product)
Another tip, don't start your sealant tape at the corner, and bend the sealer around the corners vs making a new strip for each side- both will invite an air leak.

So with the layup complete, I cut out a piece of bagging film, installed the vacuum fitting and sealed it to the aluminum plate. When putting on the bagging film, you want to have excess bag, so that the film can conform to the laminate (not so dificult when you're doing a flat panel). That will require pleats in "non stretch" bagging film like this stuff.

When I put the sealing tape on the aluminum, I didn't have anything to seal the pleats. Tip- put the tape on the bagging film, that way the pleats are easily sealed

Ok, the moment of truth. I plugged in the vacuum pump and in less than 10 secconds it removed the air from my "mold". I discovered one leak at one of my pleats. It was easily patched with a small piece of sealing tape.

It's easy to see the excess resin being pulled up throught the perforated release film and into the bleeder cloth

Here on the vacuum gauge you can see I'm pulling 26.5 inches of mercury.

A rough, but close estimation of pressure is 2 inches of HG = 1 PSI. So I'm pulling approximately 13 PSI of force on this laminate. The layup is 10" x 13" or 133 square inches. Thats giving me 1730 lbs of pressure :blink:

After a few hours I got impatient, shut down the pump and stripped the mold.

Ignoring the remianing bleeder cloth along the bottom right, you can see it looks a little on the dry side over a large part of the laminate...basically where is looks white instead of black

With the laminate pulled from the "mold", 3 errors, either in jugment or proceedure, were observed. The first was the dry appearance of the top layers of fiberglass. Once I cut the laminate open, I discovered that the source of the discoloration was not a lack of resin, but a lack of adhesion to the core material....not good. 2nd was air pockets trapped along the edge of the core material. I had hoped the vacuum bagging would automatically remove all the air and force the fiberglass fabric to conform to the core, but I was mistaken The 3rd flaw wasn't obvious until I removed the laminate, then BAM! there it was in all its harsh critisism-

This air pocket was trapped between the core and bottom 2 layers of fiberglass. I had squeeged the core, but I didn't use a roller....because I didn't have one.....:dry: Also the foam is a closed cell matrix that traps any air under it.

So, a recap of the lessons learned on experiment 1: Lets try a core material made for composite laminates. If the core material has any thickness to it, I need to either bevel the edge to allow the fabric to conform easier or lay in a fillet of low density filler to fill the gap. The low density filler would be made of the epoxy resin and microspheres (tiny glass baloons). Last, I need to make or buy a roller to make sure I force as much air as possible out of the laminate so I don't get those nasty air pockets

I didn't feel like ording a laminate roller and waiting for it to be shipped, so I made one. I'm sure I could have done the same thing with a wooden dowel, but I had some 3/4" aluminum round stock and an old paint roller laying around, so I made one

I cut the aluminum on the lathe, and just chopped and threaded the paint roller to accept the new roller. Looks just like a pro roller...kinda :laugh:

Experiment #2! I am incorporating Coremat as the laminate core material in an effort to eliminate my first 2 problems. The Coremat has perforations in it to allow the transfer of resin and air through it, but is designed not to absorb much resin. It is also compressable, so I am hoping that the edges will squish down, removing the trapped air along the edge. I'm also going to try and make the pleats line up with the edges of the coremat. Maybe I can get the pleats force into the edges and push any air out......maybe.

I forgot to show the what the PVA looks like whe delaminating the mold. It's basically a very thin plastic-

On the second layup, I'm going to forgo the PVA, and just wax the aluminum. I'm a little nervous, since I don't want to permanently glue a bunch of fiberglass to my aluminum, but it's supposed to work. Oh, and I don't have any dedicated mold release wax, so I used car wax. It shouldn't be THAT much different, right?

I mixed up some more epoxy. This time, instead of placing the fiberglass on the mold dry and pouring epoxy on top, I poured the resin on the plate first

Using my trusty bondo squeege, I spread it out

And went to work laying out the fiberglass and whetting it out as usual. I need to learn to not be so stingy with the resin on the first layers. You'll see why later.