3D Printed Tellurion
I had worked on an Orrery/Tellurion project a while back, but never posted it as I wasn’t happy with how the whole thing worked.
I had other projects to work on, so I shelved it…Literally put it on the shelf, from where it stared at me, every day, until I recently decided to get back to it, and start from scratch with a new design.
So this is a Tellurion, representing the interaction of the Earth/Moon/Sun system. It’s entirely 3D printed, aside from ball bearings, a few metal shafts, and a lot of screws.
While not absolutely scientifically exact, especially due to the fact that it’s made of plastic, I tried to get it as close as possible in terms of gear ratios and movement.
The whole base of the tellurion is actually a 3-stage planetary gearbox designed to provide a 365.25:1 reduction ratio with a very small error margin. The Earth’s rotation is directly linked 1:1 to the manual input wheel through a series of shafts and miter gears, while the Earth’s orbit is carried by the final output of the planetary gearbox, with a lot of torque.
The Sun’s rotation is based on a 25.05:1 reduction from the Earth’s rotation (the yellow gear train), while the Moon’s orbit (dark blue gear train) uses a 29.5:1 ratio from the Earth’s rotation speed, representing the synodic period.
The Moon rides on a disc tilted at 10 degrees to show the inclination of its orbit form the ecliptic plane (close to 5 degree in reality, but that wouldn’t be very obvious). And the Moon keeps showing the same side towards the Earth.
The Earth is tilted 23.5 degrees, and additional gearing keeps the axis orientation fixed in space while orbiting the Sun, as it normally points to the North Star.
I’m happy with the result, and this took a lot of design work. The gears have very tight tolerances and the whole thing has a very low backlash, even though plastic gears will always produce some noise and some wobble.
It was all printed in PETG, except for the globes, which were printed in resin a while back, and hand painted.
Check out the YouTube video: