This thread has been in such desperate need of an update, you might say it's starting to "mold".
The past year has been pretty hectic, particularly with my wife and I finally buying a house, so this project has certainly taken longer than I had planned. That being said, I'm very pleased with the results and hope to give you a detailed look into my process for molding and shell casting...
First, let's take a look at the buck, which was made by myself and forum member christphen. I took these photos shortly before covering the buck in clay prior to building the fiberglass support jacket (and yes, I rebuilt the fiberglass jacket to make it support the mold better before pouring the silicone).
I'd also like to give a shout-out to Vince, who gave me some invaluable advice throughout this proect. Thanks, chief!
I fixed a few details that were bugging me; first, I widened the space between the ribs on the Gun Mount, and added texturing to the side of the Power Cell (which I know isn't technically accurate, but it just didn't look right or consistent without it).
After bolting the master to the board, I sealed the edge with clay and proceeded to cover the entire thing in plastic wrap and about 3/4" of non-dry clay. When prepping your clay, you should roll it out into sheets about 3/4" thick and cut it into slabs. Also, don't forget to add the 1" thick perimeter after the initial surface is laid; this is critical for your mold to grip the sides of the support jacket.
Before proceeding, it might be a good idea to talk about these razor throwing cards I made...
What you see here is nothing more than cheap playing cards covered in aluminum tape (which is extremely useful stuff, by the way). These will be used to form the barrier that separates each half of the fiberglass support jacket. I opted for three pour spots made from 3" PVC couplers, which will also serve as additional keys once the mold is done. They should be positioned at the highest points of the buck.
A quick note on the pour spouts - while you can use pretty much anything for these, avoid cups or tubes that have a taper to them - this makes it more difficult to get the mold flush into the jacket when you need to reassemble the whole thing after casting a shell.
I can't stress the importance of keys - pretty much every vertical wall should have them. I made them about 1/2" thick and 1.75" wide. There's no significance to the red clay; the store was out of white, and I thought the white and red combination gave it slight Ecto-1 look...
After I had enough keys and had smoothed the clay out as best as I could with a damp sponge, it was time to lay the fiberglass for the support jacket. Never a fun job, but I've done enough fiberglassing that it doesn't really bother me anymore. However, here are a few tips for first-time fiberglass builders:
1. Fiberglass is dangerous; don't inhale it. Use a respirator in an outdoor or ventilated environment.
2. You'll need a ton of disposable chip brushes, rubber gloves, and mixing containers. All of these can be obtained at the dollar store (assuming you're not ordering in bulk and doing this full-time).
3. Lay down some sort of covering on the ground/floor. A big cut-up cardboard box works great.
4. In warmer weather, the fiberglass resin will cure faster; as a rule of thumb, give yourself about ten minutes per 8 oz. batch. Of course, your working methods and amounts will vary.
5. When fiberglassing over the clay, lay about 1.75" of gaffer's tape around the perimeter; this will help prevent the fiberglass from bonding to your board.
6. As you build up your layers (using more of a stabbing motion that actual brushing on the resin or mesh), wait for it to dry and inspect for holes, thin spots, etc. I used a sharpie to highlight these points to ensure that I didn't have any weak spots in the support jacket.
A self-portrait before starting on the next layer...
I seem to have forgotten to take any more photos of the support jacket in progress, so we'll jump ahead to its completion.
Now just bolt the two halves together, add several 1/8" OD air holes, seal the center seam with clay or hot glue, coat the interior of the jacket in petroleum jelly, bolt the entire jacket down to the board, seal the perimeter with clay, and you're ready to go!
As for the bolts, don't cheap out; use 1/4-20 thumb bolts with butterfly nuts - this will make assembling and disassembling the shell much faster.
Since the silicone pouring is a very precise and nerve-wracking experience, I didn't get any good photos, so we'll jump ahead a bit. After removing the support jacket, which came off with surprisingly little fighting, it was time to peel back the mold...
Now for the moment of truth...
I'll go into the actual casting portion of the project in my next post...