The concept of building a clock haunted me for quite a while. The only problem had been I had no idea of how to create a time measuring device that is unique, one of a kind. After all, humans make functional mechanical clocks for over 800 years, when Villard de Honnecourt created first practical escape mechanism.
It struck me during a trip I took in 2005 to Acadia National Park, Maine. The idea was simple. Make an arm with the hour dial spin around a stationary minute dial. Within a couple of minutes, I had it all drawn in my head. All the conceptual sketches and drawings were done by the time the plane’s tires touched the runway on my return to Chicago. The only remaining task to complete was to manufacture the prototype. The frame was milled out of aluminum and fitted with purchased bronze bushings. Precision shafts were cut to length, and plastic gears were pressed onto them. It took me about two months to complete the entire project, including custom made dials and hour hand.
To propel the clock and guarantee the accuracy of the device, a synchronous motor (class AB) controlled by the output frequency of the standard home power outlet was used.
Technical data: Input – synchronous motor - 20 RPM, 1 x worm gear set 1:40 ratio, 1 x worm gear set 1:30 ratio, Output – 1/60 RPM, The arm makes one revolution per hour
Hour dial – Two bevel gear sets transfer motion to a 24 tooth, 24 Dp (diametral pitch) spur gear. That gear meshes with identical 24 tooth spur that is mounted on the same shaft as the dial. The second gear’s role is to reverse the direction of rotation of the dial.
A 1:1 overall ratio allows the hour dial to stay in the same position regardless of the arm orientation.
Hour hand – Similar configuration as the dial but the 24 tooth gear has been replaced with a 23 tooth spur. Because of this, the hand lags the dial by 1/24 of the revolution every revolution, indicating passing hours. It completes a full rev. in 24 hours.