CHRONOS Annual Clock - IoT Circular Calendar

The CHRONOS Annual Clock is a sophisticated perpetual circular calendar. It allows users to think about time in a new way, with the annual cycle of seasons, solstices, equinoxes, and months read by a hand that indicates not the minute or the hour but the day. 

On startup, the ESP32 microcontroller inside CHRONOS will connect to your WiFi network and get the current date and time from the internet. The motorized hand is moved to the point on the clock face representing the current date. The hand continues to rotate forward slowly as the days go by, lending a new perspective on the passage of time.

The face of the CHRONOS Annual Clock resembles a conventional clock but varies in important details. This is because CHRONOS is keyed to the physical phenomena that inform timekeeping.

The start of Summer* is at the top of the clock face where 12 or 24 would be, and Winter is opposite. The Solstices were chosen as the key points due to their importance as astronomical and geophysical events.

* Available in reverse for those in the Southern Hemisphere.

CHRONOS has a classically styled cabinet that was designed to look great when printed with Wood PLA. It can be built in several attractive styles using the included parts. A style gallery is included in the Assembly Guide so you can find the look for you!

How to Read the CHRONOS Annual Clock

Day Ring (outer ring)

The space between marks around the circumference of the face denotes a group of 5 days. The marks themselves are the divider between days and, therefore, denote a midnight (e.g., the midnight separating the 5th & 6th of a given month). The width of the hand at its end is approximately the same as a day sector.

Months with 31 days have a day sector at the end of the month. February 29 is included on the clock face; it is skipped over when it is not a Leap Year.

You'll soon be able to look at CHRONOS and say, “today's the 10th” or whatever date it is with practice.

Zodiac Ring (middle ring)

More than decorative, the hand is an analog for the Sun’s yearly journey through the Houses of the Zodiac.

Season Ring (inner ring)

This ring shows the typical dates of the solstices and equinoxes. December 21 is the most stable date for the 21st century; equinoxes and the Summer Solstice have more variation. 

Before You Get Started:

• Important: Download the CHRONOS Assembly Guide PDF and read it all the way through before starting.
• A complete Bill of Materials including both printed and non-printed parts is included in the Assembly Guide PDF.
• Some familiarity with hobbyist electronics and microcontrollers is assumed. No soldering is required but it may be helpful.
• Be sure to download both the main print profile and also at least one of the offered clock faces. These are available either in English or with symbols for an International audience; and with the seasons marked for the Northern or Southern Hemisphere.
• Advice from Bambu Lab for those with P1- and X1-series printers on maximizing print volume.

Examples created with Bambu Lab PLA Basic in Bronze and Silver; Bambu PLA Wood in Classic Birch, White Oak, and Rosewood; AMOLEN Rosewood Wood PLA; and ELE'GOO Bronze Silk PLA. For best results, use a stainless steel 0.2 nozzle for clock faces. 

Frame rivets courtesy of Parametric push-in rivets. https://makerworld.com/en/models/1136154-parametric-push-in-rivet

Updates

• June 17 2025 - Added Precision Faces for CHRONOS. The Precision Faces are graduated for each day of the year. Your calibrated CHRONOS will show the current day date to a high degree of accuracy.
• May 05 2025 - Added Chronos code as a text file attached to this model for the benefit of MakerWorld CN users unable to reach my GitHub. Copy and paste into Arduino IDE.
• April 27 2025 - The CHRONOS-QZ Quartz Clock Mechanism Conversion Kit is now available. (MakerWorld | MakerWorld CN)
• April 17 2025 - Added a print profile for a hand with a counter-hand. The shorter counter-hand indicates the season in the opposite hemisphere.