Fiberglass Molding

I've been watching one of Windy's videos about making fiberglass cowls. What are other's experiences doing this? What sort of mold material do you use? Is the liquid silicon stuff that Windy uses easily available?

I haven't seen Windy's tape, but I made a carbon cowl for my Impact and seven for the B-17. I vacuum bag them in female molds. Casting epoxy works dandy for the mold. You may even get away with plaster. I used silicone on the B-17 cowls. Silicone is flexible, so you can get the part out, but one unforeseen problem is that the vacuum pushes the weave into the mold and leaves a bumpy surface that has to be filled.

The most useful advice, I think, is: Don't use dope or lacquer on the plug or mold. When you do and it gets stuck, remember that I told you so.

Hi Howard,

Where do you get the silicon for the mold? West Systems? I planned to go to West Systems (since they are in Tacoma) to buy the epoxy. I may try plaster. Hadn't thought of that. I wanted something that will hold up. It seemed the nice thing about the silicon was that you didn't have to use release agents or mess with a lot of that sort of stuff.

Thanks,

Holding up is no problem unless the plug or part gets stuck in the mold.

The silicone is Silastic E. Dow Corning, I think, makes it. I got it at a place just south of downtown Seattle: Atlas Supply, 1736 4th Ave. S., 206-623-4697. I recommend casting epoxy, though, with Frekote 700 release agent.

Howard

I've followed your work on the B17 with great interest--congratulations--but you mention vacuum pumps and bagging.

What sorts of pump should we look at and how do you bag your pieces?

Thanks, Geoff

I contributed only a small fraction to The Bomber. It was an honor to get to participate.

I use a Gast vacuum pump from CST (http://www.cstsales.com/). Generally for wet-layup parts, I use Shell Epon 815 resin with DETA hardener. I put perforated .001" or .002" Teflon film next to the part, then some bleeder cloth, then a .002" nylon bag with plenty of pleats. I get most of the stuff from Boeing Surplus, but CST and others have it, too.