This Planetary Gear Glock Is a Wonder of Mechanical Design

There are many methods humanity has devised over the years to track the passage of time. From sun dials, to hourglasses, to water clocks, we have always tried to figure out ways to more accurately mark the passage of time. Until the digital era, mechanical or electromechanical clocks were the most precise timekeeping devices that people had access to. Anyone who has seen the intricate gears of a Swiss watch knows just how complex mechanical timepieces can be. In celebration of those classic clocks, Looman_projects built this Planetary Gear Clock that combines traditional mechanics with modern and precise digital electronics.

As Looman_projects points out in the Instructables tutorial that they wrote for this project, mechanical clockworks are nearly impossible for the average hobbyist to make at home. The gears needed for a truly mechanical clock are just too small and detailed for most people to fabricate, as they’re usually produced at tiny scales using incredibly precise machine tools. This clock, on the other hand, uses a large planetary gear set to move the hour and minute hands. Because the gears are nice and big, they can be fabricated using tools that are much easier for makers to access—most importantly, a laser cutter or 3D printer.

Planetary gear sets have four distinct parts: the outer ring gear, the planetary pinions that circle around inside of the ring gear, the planetary carrier that keeps those separated, and finally the sun gear at the center. By altering the relative sizes of the gears, you can change their RPM (Rotations Per Minute) relative to the input shaft. In this case, the input comes from a stepper motor driven by an Arduino board. An RTC ensures that the time is kept accurately, and a Hall effect sensor double checks to make sure the revolutions are kept in sync. The gears are sized so that sun gear makes one revolution once every 12 hours, while the planetary carrier, which doubles as the minute hand, makes one revolution once every 60 minutes. If you want a clock that is fascinating to watch, this project is definitely worth tackling.