Clock made with “24 clocks”

Description

For several years I saw an artist making a display using a lot of analog clocks. The idea has been with me a long time. 5 years ago I built a similar clock using servo motors, however the result was not exactly as accurate as I was hoping. Thus, time for a next try.

Project summary

In this project I tried to build a new display/clock using clocks. One digit was constructed by using 6 “clocks”. The whole project required a considerable CAD design with some programming. 

My responsibilities

• CAD design - prototyping and suitable solution finding

• Printing the clock

• PCB design and component selection

• Building, testing and programming the clock

Results

This project took some time to implement. On several occasions the project waited several months before I was able to continue and therefore the total time is a very long one.

The project started with the CAD design. It took me several iterations till I was happy with the operation of single 2 dials. The whole one digit has 6 “clocks” and 12 dials that need to be rotated. Due to limitations from the 3d printer and stepper motor size I was not able to reduce the overall size. Thus, in the end the whole 4 digit clock is relatively large.

The hardware design took me several months of trial and error including several breaks. Eventually I was so far as to order the PCBs. I planned to control the 4 digits with 1 MCU as I have done with several other projects. However, this time I had large EMI issues. First I tried to reduce the EMI by using very good twisted and shielded cables, unfortunately without much improvement. Eventually I think there is more than just EMI that affects communication. 

After a few months of break I decided to control each digit separately with its own MCU. I wanted to communicate between the MCUs by using I2C, nevertheless my wiring was not good enough and I had to look for another approach. Then I tried the ESP-Now protocol and was able to control the dials as intended (look at another project called: “Controlling several MCUs wirelessly”).

In the end the project took much longer and much more effort than anticipated, especially in the areas where least expected. Overall I'm happy with the outcome and the display works. What could be improved is the calibration of the dial movements. Due to inaccuracies there is some movement between the gears and that causes some inaccuracy.

Used tools

SW: Arduino IDE, Fusion 360, Easy EDA, 

HW: ESP32, Stepper motor, 3d printer, PCB