We’re going to use 13 because it’s how many times our Moon orbits us (Earth) in one year. We can control this whole movement with a really simple 2 cog set up.įirstly, we need a value we can base our cog calculations on, this needs to be a whole number, as it will equal an amount of teeth on a cog.
We’re going to focus on the Earth’s orbit around the Sun, and the Moon’s orbit around Earth. Lets first look at how cogs work in an orrery. We will go over it many times through this how-to. It’s simple and we’re going to take it step by step. I based the solar system model around the design of his Orrery, and it functions in a very similar way, however our calculations are going to be slightly different. Now before we get into the 3D side of things, I want to give a shout-out to Dragonator on the Instuctables forum. Now for our 3D Orrery it’s possible to cheat it completely as we don’t need to be restricted by the real world limitations of cogs, but where is the fun in that? I thought a fun experiment would be to have functioning gears that drive the positions of the planets, as they would in reality. It’s basically a mechanical model of the solar system, usually driven by a system of gears and cogs.
