Mechanical Digital Clock (24 hours)

This is a mechanical digital 24-hour clock. It is driven by a single motor (or by hand) and uses geneva drives and camshafts to display the correct patterns on four mechanical seven segment displays.

Non-printed parts

• 46x Square M3 nuts
• 50x M3x6 screws (or longer)
• Plastic glue
• Electronics (see below)

Digits

In addition to the files in this model, you need to print four mechanical seven segment displays. From left to right, the digits are:

• Seven Segment Display with the cam_0-2_CW.stl camshaft
• Large 24h Seven Segment Display with the cam_0-23_CCW.stl camshaft
• Seven Segment Display with the cam_0-5_CW.stl camshaft
• Seven Segment Display with the cam_0-9_CCW.stl camshaft

Motorization and electronics

The electronics setup for the motorization will depend on which particular parts you want to use. I provide some information about my setup for reference but this is not a comprehensive tutorial. The motor mount part fits a Nema 17 stepper motor and the electronics enclosure fits a 400-point breadboard. These are the parts I used:

• Seeduino XIAO
• Nema 17 Bipolar 1A 13Ncm 42 x 20mm Stepper Motor
• TMC2209 Stepper Motor Driver
• 12V 2A Power Supply with a 5.5 x 2.5mm DC Plug
• LF50CV voltage regulator to power the Arduino
• push buttons and pull down resistors

Assembly

1. Attach two dots to the separator with glue. Insert four square nuts and glue them in place.
2. Insert 3 square nuts into the gearbox
3. Place the four digits next to each other
4. Put the gearbox on top of the digits and insert 8 screws
5. Place the separator between the digits and attach it with 2 screws
6. Turn the assembly upside down and attach the bottom cover with 10 screws
7. Insert 2 square nuts into the motor mount
8. Attach the motor to the motor mount with 4 screws
9. Attach the motor mount to the gearbox with 2 screws
10. Use an axle to turn all four digits to 0. The second display has 3 different zeros, you need the one that comes after a 3.
11. Put down the four gears and make sure that the alignment line points to the front
12. Place an axle into each gear
13. Insert a square nut and a screw into the motor gear, but don't tighten the screw
14. Attach the motor gear and tighten the screw
15. Optional: Electronics box
    1. Insert 5 square nuts into the bottom part of the electronics box
    2. Place a breadboard with all your components into the boxHere is another photo for wiring details:
    3. Attach the top cover with 3 screws
    4. Push it into the main assembly and attach it with 2 screws
16. Put the top cover on the gearbox and fasten it with 3 screws