SP9: Large Silent Desk Clock
This is an oversized version of the SP6 Silent Desk Clock with many enhanced features. The dial is easy to read without hiding the gears. It uses standard components with an accuracy of about a minute per year. The stepper motor driver is completely silent.
The overall size is 12.4" (31.5cm) wide by 11.8" (30.0cm) tall and 5.0" (12.7cm) deep. The largest components can be printed on a Prusa Mini or any printer with a 180x180mm print area. The total print time is just over 50 hours using 0.65kg of PLA filament.
The driver circuit uses standard components that are available worldwide. An Arduino Nano runs the algorithm. It plugs into a CNC Shield V4 with a TMC2208 stepper motor driver and a DS3231 precision real time reference clock. A standard NEMA17 stepper motor is used.
The clock was designed using the following criteria:
1) The clock needs to look good. The solid dial makes it really easy to read the time. The gears were extended beyond the frame to balance everything.
2) It must be accurate. The DS3231 precision real time reference clock has internal temperature and voltage compensation to stay hold an accuracy of about a minute per year. The algorithm is self-calibrating to lock the sweep second hand to the real time within a fraction of a second.
3) It must be silent. The TMC2208 stepper motor driver runs incredibly smooth and silent.
4) It must use standard components. All of the electrical components are readily available on Amazon or equivalent source.
This clock has easily become my new favorite design. The silent operation allows it to work in any room. The hands are easy to read, and it never needs winding.
Video of the Clock in Operation
Updated Motor Driver Video