Casting Loads

[Keith Hayes]

After the success with the mine prop loads a while back, I have been itching to cast something else. Never mind 3d printing,  let's go old school with rubber molds and casting resin!

Climax needed some large timbers, about 12x12s as near as I can figure. These would eat up a bunch of basswood,  so how about a casting? I got some 3/16ths square balsa at the local art supplier and made my master. According to photos these are about 20-foot-long timbers. After the glue set, I emphasized the edges by scoring with a knife.

I reused my styrene mold bathtub from the mine prop project. Micro Mark makes the 2-part rubber for the mold. Mix 1:1--easy!

When the rubber is ready,  overnight,  you are ready to cast. Micro Mark also sells the 1:1 resin. I have been casting in a block of 1/2" square balsa to save on resin and lighten the loads a bit. I place an old business card over the casting and hold it with a weight. The I manipulate the balsa into place with a Peavy (a knife blade or tweezers). After about 30 minutes the casting is ready to remove. This material starts clear, but dries white.

In the time it has taken to draft this post, I have already made another set of castings! I will sand the base flat and then prime and paint. I have seen the timbers shipped both on flats and in coals. Don't know how many loads were shipped at a time, but I will make 4-6 to provide a steady supply for management to keep on building. Dunnage and bracing will be made from basswood strips.

More when the parts really cure and I get them finished.