Single Rotor Moiré Clock

prusaprinters

<p><strong>This clock shows both of minute and hour hands with a single rotating part.&nbsp;</strong></p><ul><li>It uses moiré effect to optically show the minute hand which rotates 12 times faster than physical rotation with hour hand.</li></ul><figure class="media"><oembed url="https://youtu.be/ubjwEHqmXWg"></oembed></figure><h3>How to make</h3><p><strong>Parts</strong></p><ul><li>Stepper motor 28BYJ-48 and driver board comes with</li><li>Micro computer (Arduino nano, etc.) to control the stepper motor</li><li>2mm x 10mm tapping screw* 2</li></ul><p><strong>How to make</strong></p><ul><li>Print all parts with supplied posture. Supports are not necessary.</li><li>Use opaque material for cover and rotor. Use transparent or translucent material for the rear cover.</li><li>Confirm the smoothness of the rotation of the rotor.</li><li>Find the top of the cover, as illustrated below.</li><li>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.</li><li>Insert the rotation axis of the motor to the rotor.</li><li>Attach the pillar with 2 x 10mm tapping screws.</li><li>Insert the foot of the pillar to the stand. If the stand is loose, please use welding or glue.</li></ul><p>To set the time, switch for fast forward function is necessary.</p><h3>Principle</h3><ul><li>Both cover and rotor have many holes with repeating pattern.</li><li>Cover has 11 periods a round, and the rotor 12 periods.</li><li>Therefore, moiré rotates 12 times faster than the actual (physical) rotation.</li><li>The rotor speed is as same as the hour hand (two rotations per day).</li></ul><p>About moiré <a href="https://en.wikipedia.org/wiki/Moir%C3%A9_pattern">https://en.wikipedia.org/wiki/Moiré_pattern</a></p><p>This clock uses the principle described in the section "Speedup of movements with moiré", <a href="https://en.wikipedia.org/wiki/Line_moir%C3%A9#Speedup_of_movements_with_moir%C3%A9">https://en.wikipedia.org/wiki/Line_moiré#Speedup_of_movements_with_moiré</a></p>