This solar system model (sometimes called an orrery) was a passion project of mine for several years. It features 8 planets orbiting the sun at (roughly) the correct relative orbital speeds. The model is driven by just one power functions XL-motor, and all the orbital periods are set in the gearbox in the base of the model (the [average] accuracy of the model is 96.5%). The outputs of the gearbox are connected to the ends of the planetary axles that run vertically through the centre of the main structure. These are connected to a gear train on each platform which drives the rotation of the planetary rings which are themselves sandwiched between non-rotating rings, forming a kind of bearing to which the planetary arms are attached. The planetary rings are able to rotate smoothly by placing 1 stud round tiles in the groove of the rings (credit to Lego Technic Engineering for this brilliantly simple idea - https://www.youtube.com/watch?v=vnZKlIbSX1M). The planetary arms were one of the hardest aspects of the model to get right, as I wanted to keep them simple, strong and aesthetic. After trying right angled and then curved arms (these looked really cool but simply weren't strong enough) I settled on straight arms set at an angle simply by resting on axles.
Working on this model was the perfect balance of challenging and rewarding, and I'm really pleased with how it turned out.
This is a big model. Make sure you have enough space to display it! The base is 40cm x 40cm and the height of the model is 93cm. The furthest planet, Neptune, lies 50cm from the Sun so when the model is running it sweeps out a circle with a diameter of a metre.
The high quality instructions were made in BrickLink Studio and are made up of 417 steps (many of which are repeated). The building process is laid out logically - you will start by building the gearbox, the base and the main structure separately before connecting them all together. Then it's on to adding the rings, and finally the planets and their arms. You can see a sample of the instructions in the gallery above.
If you have any questions or feedback I'd love to hear from you. You can reach me through email: email@example.com