I led a team of engineering students to design, fabricate, and install a working scale model of the Solar System on the ceiling of our residence hall.
Design and engineering
An orrery is a mechanical model of the Solar System, stylistically depicting the relative orbits of any number of heavenly bodies. A grand orrery is one which includes all the inner and outer planets, as known at the time of construction.
The planets all orbit the sun at the correct relative speeds, sped up approximately 2000 times to make their motion visible to the casual observer. In our model, Mercury orbits the sun once each hour, Earth orbits in about 4.5 hours, and Pluto (which we included for sentimental reasons) takes 43 days.
We also endeavored to make our Grand Orrery physically reflect the average orbital distances and the planetary radii, using rather severe logarithmic scales for both.
In keeping with the traditions of historical orreries, our Grand Orrery needed to be both a functional mechanical system, and an elegantly decorated piece of art. We chose to make the gears from brass for both its self-lubricating properties, and its visual flair. Each gear pair was adorned with individualized artwork, some pertaining to the specific planet it drove, others hiding meaningful messages to future students.
I designed and modeled the Grand Orrery in Solidworks, developing a multi-tiered system architecture, which utilized mainly off-the-shelf components (stainless-steel tubes, thrust bearings, keyless bushings, and more) to support our custom-designed gears. We fabricated the custom parts using a CNC mill, water-jet cutter, and various other tools in the engineering school shop.
We installed the Grand Orrery in May 2012, and it is still happily spinning away on the ceiling of Andrews Hall to this day. Be sure to check it out if you find yourself in Boulder, CO.