A clock with a perpetual calendar mechanism that correctly handles all types of months, including February in a leap year, has been developed. Despite the weak torque of a quartz clock movement, an improved mechanism has been designed to mechanically realize this complicated function.

Features

• The calendar advances automatically, so you do not need to adjust it until March 2100. In the morning at March 1st, 2100, this clock will show Feb. 29th. So please raise the main arm once and all set, if you will be still alive and remember it.
• It uses a commercial clock movement, so it can work for a long time without an external power supply.
• The calendar is easy to adjust by directly rotating the clock hands.
• The rear surface is flat, making it easy to hang on a wall beautifully.
• The skeleton design exposes the mechanism inside, making it easy to assemble.
• There are no visible screw heads on the front side.
• This clock is easy to print, as all parts can be printed without support structures.
• You can make this clock using popular 3D printers that can print objects up to 180mm x 180mm (use the square back plate and separate main arm).

Subdials for non-English languages are available at
https://www.thingiverse.com/thing:5986655
(languages on request, but alphabetical characters only)

Contrary to the former design with stepper motor, it uses not rubber bands but a weight and the gravity. Therefore, the calendar mechanism works only when the clock is upright on the wall.