Single Rotor Moiré Clock

This clock shows both of minute and hour hands with a single rotating part. 

• It uses moiré effect to optically show the minute hand which rotates 12 times faster than physical rotation with hour hand.

How to make

Parts

• Stepper motor 28BYJ-48 and driver board comes with
• Micro computer (Arduino nano, etc.) to control the stepper motor
• 2mm x 10mm tapping screw* 2

How to make

• Print all parts with supplied posture. Supports are not necessary.
• Use opaque material for cover and rotor. Use transparent or translucent material for the rear cover.
• Confirm the smoothness of the rotation of the rotor.
• Find the top of the cover, as illustrated below.
• Stack the cover, rotor and rear cover, then weld front and rear cover with soldering iron. I think you can use some glue also, but please be careful not to lock the rotation of the rotor.
• Insert the rotation axis of the motor to the rotor.
• Attach the pillar with 2 x 10mm tapping screws.
• Insert the foot of the pillar to the stand. If the stand is loose, please use welding or glue.

To set the time, switch for fast forward function is necessary.

Principle

• Both cover and rotor have many holes with repeating pattern.
• Cover has 11 periods a round, and the rotor 12 periods.
• Therefore, moiré rotates 12 times faster than the actual (physical) rotation.
• The rotor speed is as same as the hour hand (two rotations per day).

About moiré https://en.wikipedia.org/wiki/Moiré_pattern

This clock uses the principle described in the section "Speedup of movements with moiré", https://en.wikipedia.org/wiki/Line_moiré#Speedup_of_movements_with_moiré