Rotary digital clocks driven by a single motor.

• Now you do not need to buy reflective photosensor to find the origin of the rotors. It uses physical endstop which forces the motor to stall at origin.

Features:

• Photo sensor to find the origin is not necessary. Only popular parts (ESP32 micro controller and 28BYJ-48 stepper motor) drive the clock.
• It uses physical endstop which forces the motor to stall at origin.
• You can choose less noise version without click stop (numeric type only)
• WiFi setting via smartphone (SmartConfig of ESP32).
• Less part count. Only one non-moving parts (case, axis and foot are integrated into a single body).
• Three types of cased bodies are supplied. (numeric type only)

Several variants

• Slanted case for better visibility on a desk
• Numeric type clocks with click stops. Though it makes some noise, you can expect better digit alignment. Use STLs in "numeric-click" folder.

Difference from former design

Previous rotary clocks, [https://www.thingiverse.com/thing:4931539](https://www.thingiverse.com/thing:4931539) [https://www.thingiverse.com/thing:4939540](https://www.thingiverse.com/thing:4939540) , used a reflective photosensor to find the origin when power is on. This new design is simplified without the photosensor but it can be still initialized automatically. To realize that function, this thing has physical endstop (a blockage of rotation) and the motor is forced to stall when it reaches to that position. The torque of 28BYJ-48 motor is not so strong. Contrary to common DC motors, electric current passes through the stalled stepper motor is not so large. Therefore this method is perfectly safe.

How to make

You can choose with or without click versions for numeric digit type clocks. 

• Click version makes some noise when wheels rotate, but you can expect better text alignment. This version has a bump on the top of the axis, and rotors have corresponding dips. Use STL files in "numeric-clock" folder. 
• All four types (naked, round-case, square-case, slanted-case) are supplied. 
• There is no clickless version for the 7-segment type clock.

You need

• ESP32 based micro computer
• 28BYJ-48 geared stepper motor and driver circuit comes with
• Several 2x8mm tapping screws
• Wire, soldering iron, lubricants such as silicone oil

How to make

• Print parts with supplied posture. Only the cased bodies (round-case or square-case) need support at front windows.
• Remove blobs and debris well. Especially, the both sides of rotors should be smooth.
• Attach circuits and the motor into the axis with 2x8mm tapping screws.
• Stack all wheels. For numeric type clocks, place spacers among wheels.

WiFi setting

You can set SSID and password of your WiFi using smartphone app.

This function is named SmartConfig. The apps for setting are at

Android: [https://play.google.com/store/apps/details?id=com.khoazero123.iot_esptouch_demo&hl=ja≷=US](https://play.google.com/store/apps/details?id=com.khoazero123.iot_esptouch_demo&hl=ja≷=US)

iOS: [https://apps.apple.com/jp/app/espressif-esptouch/id1071176700](https://apps.apple.com/jp/app/espressif-esptouch/id1071176700)

The status of WiFi connection is indicated by the motion of the rotor.

• Large reciprocal motion : connecting to WiFi of past setting stored in non-volatile memory.
• Small reciprocal motion : SmartConfig mode. If 30 seconds of WiFi connection trial fails, it automatically moves to the the smartConfig mode (waiting for the setting from smartphone app.)

Please not that your smartphone should be connected to 2.4GHz WiFi.

Acknowledgement:

Thanks to airtcp. His original source code can be seen at the page of previous version, [https://www.thingiverse.com/thing:4931539](https://www.thingiverse.com/thing:4931539)

Note : For the things of this page, please use the codes "numeric.ino" or "7seg.ino" downloaded from this thing's page.

FAQ

Q1. Why don't you supply silent version of 7-segment clock?

A1. Actually I made it, and found that 7-segment clock with round axis and spacers between wheels has much friction. It tends to be stuck with weak torque of 28BYJ-48 motor. Therefore I used previous design with click stop by polygonal shaped axis and rotors.

Q2. A rotor is unintentionally rotated by the neighboring rotor.

A2. Please make sure that the touching surface of the neighboring rotor is very smooth. The position of the stepper motor is also very important. If the motor is not centered precisely, the second wheel is unintentionally rotated. It is also useful to increase the thickness of spacer if you are making the numeric type clock. For 7-segment clock, do not set the first wheel too tight. Some free space among rotors are necessary to suppress friction.

Q3. Can I use Wemos D1 mini or ESP8266 based board?

A3. I have not tried them yet because Wemos D1 mini and most ESP8266 based board can not be used in Japan legally.

Q4. I would like to set WiFi settings in the source code directly.

A4. Please take a look at the top of the source code. Turn off the flag named WIFI_SMARTCONFIG (at line 10), from true to false. In this case, you should write your SSID and password at line 14-15.

Q5. How to change the source code between 12H and 24H versions of 7-segment clocks?

A5. Please take a look at the top of the source code "7seg.ino". Turn off the flag named HOUR12 (at line 4), from true to false if you make 24H clock.

Q6. I would like to place the digits of numeric clock not at the right front but a bit upper position.

A6. Please take a look at the top of the source code "numeric.ino". Change the value named DISP_POS from 0 to 1. Currently the position of digits of 7-segment clock can not be changed.

Q7. It seems that the motor is rotating to the opposite direction.

A7. Please take a look at the source code Change the content of array named port[4] at line 30.

Q8. Numbers or segments are not well aligned.

A8. Some parameters to tune the alignment are prepared in the source code. One is the KILL_BACKLASH parameter which compensate the backlash of internal gear of the stepper motor. The other parameter is in the function setup(). When the motor pushes the rotor to the endstop, it will be distorted. The value at the comment "release pushing force to align all digits better" could be tuned to compensate it.

Q9. Which body do you prefer?

A9. Currently, the slanted body. At first I designed round body as minimal shape. However, it looks too tall, compared to the width of the clock, and the digits look too small. Therefore I designed square one to emphasis the frame around the digit windows to hide the impression of the big rotors inside. Slanted version is actually a 15deg tilted version of square body.

Related projects

Minimal Mechanical Digital Clock with Network Time Acquisition [https://www.thingiverse.com/thing:4931539](https://www.thingiverse.com/thing:4931539)

(former version of numeric type clock)

Rotary 7-segment clock [https://www.thingiverse.com/thing:4939540](https://www.thingiverse.com/thing:4939540)

(former version of 7-segment type clock. Detailed description on how to show 7-segment number with only 3 rotors are there)