We’ve seen backyard casting, and for the most part, we know what’s going on. You make a frame out of plywood or two by fours, get some sand, pack it down, and very carefully make a mold around a pattern. This is something else entirely. [FarmCraft101] is casting a bronze cannon. Sure, it’s scaled down a bit, but this is the very limit of what sanity would dictate a single person can cast out of molten metal.
This attempt at casting a cannon is more or less what you would expect from a backyard bronze casting experiment. There’s a wooden flask and a greensand mold, everything is tamped down well and there’s a liberal coating of talcum powder inside. This is a large casting, though, and this presented a problem: during the pour, the halves of the flask were only held together with a few c-clamps. This ended poorly, with molten bronze pushing against the mold and eventually flowing onto the garage floor. Doing this alone was perhaps a bad idea.
The failure of the mold meant some math was necessary, and after some quick calculations it was found that more than 300 pounds pushing the sides of the mold apart. A second pour, with the sides of the flask bound together with nylon straps, was much more successful with a good looking bronze cannon ready for some abuse with a wire wheel.
This is only the first video in the series, with the next videos covering the machining and boring out of the barrel. That’s some serious craft right there.
Continue reading “Casting A Cannon Is A Lot Harder Than You Think”
Briefly, the process is to first bake the pine cones to remove any moisture. Then they get coated in a heat-activated resin for stabilizing, which is a process that infuses and pre-seals the pine cones for better casting results. The prepped pine cones go into molds, clear resin is mixed with coloring and poured in. The resin cures inside a pressure chamber, which helps ensure that it gets into every nook and cranny while also causing any small air bubbles introduced during mixing and pouring to shrink so small that they can’t really be seen. After that is cutting, then sanding and polishing. It’s an excellent overview of the entire process.
The original whistles are a peek into a different era. The bell type whistle has three major components: a large bell at the top, a cup at the base, and a central column through which steam is piped. These whistles were usually made by apprentices, as they required a range of engineering and manufacturing skills to produce correctly, but were not themselves a critical mechanical component.
