Hollow clock 2 - silent and smooth

prusaprinters

<p><strong>Silent and smooth : stepper motor version of "Hollow Clock", </strong><a href="https://www.thingiverse.com/thing:4747403"><strong>https://www.thingiverse.com/thing:4747403</strong></a></p><ul><li>Easy operation : super-easy time adjustment</li><li>Easy print : printable without supports (except optional cover.stl)</li><li>Easy assembly : gears can be set by just sliding in</li><li>Cheap : used stepper motor is very popular and cheap (around 3USD with amp circuitry)</li></ul><p>A bit smaller than original "Hollow clock" (rotor diameter : 200mm vs 160mm). Now it has no air gap between rotors.</p><p>Update Nov. 21, 2021 : "Hollow Clock 3" is released. <a href="https://www.thingiverse.com/thing:5142739">https://www.thingiverse.com/thing:5142739</a></p><figure class="media"><oembed url="https://youtu.be/TL-U4IecYIA"></oembed></figure><h3>Assembly</h3><p><strong>Necessary parts</strong></p><ul><li>28BYJ-48 5V stepper motor with ULN2003 motor driver amp board (3USD per unit)</li><li>Arduino nano or its compatible board (5USD per unit)</li><li>4 tapping screws (2 x 6mm)</li></ul><p><strong>Gears can be set easily</strong></p><ul><li>Reduction gear is set by just sliding in, using oblique axis guide.</li><li>Minute driving gear is held by the axis of stepper motor.</li><li>Hour driving gear is held by the minute gear axis.</li></ul><p><strong>For details, please look at the movie above</strong></p><ul><li>Please use a spacer if your screw is longer than 6mm or the screw will block the gears.</li><li>Check the smoothness of rotation using "stepper-test.ico".</li><li>Lubricate the gears and rotors if the clock does not work properly.</li></ul><p><strong>Circuitry</strong></p><ul><li>Arduino nano can be directly soldered to the motor driver amp board. Use D4 - D7 terminals to control the motor.</li><li>Connect GND and 5V to the driver board.</li><li>(optional) I cut the pattern to turn off the LEDs on the driver board.</li></ul><p><strong>Print</strong></p><ul><li>All parts can be printed out without support.</li><li>Remove debris and blobs around the parts well.</li></ul><p>If you turn off the indicator LEDs on the stepper motor driver board, cut the pattern as shown above, then connect necessary pins.</p><p>Troubleshooting:</p><p>From the comments to this thing, I noticed there are some different versions in the market. Some motor runs to the opposite direction.</p><p>If your motor runs to the wrong direction or generates noise with weak torque, please change the order of the numbers in code as</p><p>int port[4] = {7, 6, 5, 4};</p><p>to</p><p>int port[4] = {4, 5, 6, 7};</p><p>where the numbers are related to the pins of Arduino nano (D4 - D7).</p><p>If the motor does not run smoothly, or generates noise with weak torque, change the order to find better one. Stepper motor never breaks by changing orders.</p><p>Since a stepper motor consumes a lot of power, Arduino become unstable with low-voltage USB power source. To solve the problem, try to do the followings:</p><ul><li>Jump (short) the diode under the USB connector of Arduino nano (as left picture above).</li><li>Add a capacitor between 5V and GND (as right picture above). I used 10uF capacitor.</li></ul><p>or</p><ul><li>Use an independent 5V power source to the stepper motor amp.</li></ul><p>Mar 3, 2021 : Cover of the stepper motor and circuits are added. It is only for the standard circuits assembled as shown above. This part needs support when printing out.</p><p>With this body, you can use "Flying hands kit" which no longer connects the hour hand to the surroundings. <a href="https://www.thingiverse.com/thing:4768343">https://www.thingiverse.com/thing:4768343</a></p><p>Category: Gadgets</p>