The front fenders created a whole new set of challenges. It was hard for me to get my mind around the negative space. I originally intended to do cavity pours like the rear fenders but the geometry of the part would require some fancy claying. Then I had a “duh” moment. I’m not making Entex front fenders, I making Slave I parts. The red line shows the approximate trim for Slave, the green is where I wanted my castings to go to ensure enough meat to trim down and align to the curve of the hull.
Sometime ago beaz posted a method for molding the Saturn V cans and F-4 Phantom engines for the X-wing. He used a brace system to support the silicone in the negative space. This creates natural pour space, great venting, and allows the second part of the mold to use much less RTV. Winner!
Here is what I came up with. If you look closely you will notice some mold features that show these did not turn out quite like I thought they would.
Clayed up master with styrene rod where support posts will go.
First part poured and clay removed.
It turns out one of my support posts was in a location that would not work (oops). Luckily I had intended to use three supports, I can make due with two. Here are the molds with supports.
Second part poured.
Here is what you do when your math goes bad and you mix up way too much silicone. Panic! :wacko Grab something, anything you can pour silicone over. Preferably something you want to make castings of. I grabbed the AMT C600 rails for the AT-ST. The pour time on the RTV after vac degassing and pouring the fenders was quickly running out. I didn’t even had time to figure out which was the correct rail needed for the AT-ST. Create a quick clay dam and stick in some styrene rod for keys. To be continued…
Back to the Entex fenders, master part removed. The support structure keeps the second part of the mold where it should be.
Castings.