Silent Wall and Desk Clock

Silent Wall and Desk Clock

Silent Clock

This is a silent Clock for wall mounting or to place on a flat surface. It is designed from the ground up to be easily printed so you should have no problem with it – only a single part needs supports (the wall hanger). The maximum required print area is 180 mm x 180 mm (I used my Prusa mini as upper limit)
The clock is designed around common parts readily available online like a 5V Stepper motor, a Arduino nano and a common RTC and bearings. A more specialized component is the silent step stick which is the ultra quiet stepper driver. However you can try these common stepper drivers for 3d printers and see if they are sufficiently quiet.

Many of the parts are designed to support two-color printing via M600 command (changing filament mid print) by incorporating stepped design accents (mostly the gears and the clock face). For materials you can print everything in PLA if you wish. I myself printed the Wall Hanger (M25), the cable strain relief (M28) and the legs (M26, M27) in PETG. The remainder was mostly printed in galaxy black and pineapple yellow PLA.

I’m not an artist, I tried my best to create something simple but neat looking. If you want to make your own clock face I can create a drawing with the required mounting points.

For the two or three people in the world which like me prefer a counter clockwise spinning clock there is a variant of the clock face in the files folder. To spin the clock backwards only a single line in the code has to be edited.

The clock is set by disengaging the spring loaded gear of the stepper motor and tuning the handles manually. The RTC clock chip is only used as very precise 1 Herz Clock source.

Part List

All components have an identifiers. Parts to buy have the prefix “B” and all parts you have to make/print are marked with the prefix “M”. The screw types are not very well optimized, I just used what I had at hand at the time. At some parts you may get away with shorter/longer bolts.
I hope you can overlook the frequent occurrence of “watchface”, I only found out later that this is not an actual English word – sorry about that.
The fact that M20 is called Battery holder can be ignored for now. In theory this clock can be conveniently battery powered, however the run time is still way too bad. Maybe I will release a retro-fit design in a few moths to fix that and make battery powered operation feasible.

Parts to buy

Part Number Quantity Part Name Description
B01 5 B01_Bearing7/22/8 Standard Bearing
B02 1 B02_Stepper_Motor Stepper Motor 28BYJ-48 ULN2003
B03 1 B03_Arduino_nano Arduino Nano
B04 1 B04_Stepper_driver Silent Step Stick
B05 1 B05_RTC_PCB Real Time Clock AZDelivery RTC DS3231
B06 1 B06_coil_tensioned Small coil
B07 2 B07_M5x20 M5x20 Screw, any head
B08 1 B08_M5x24 M5x24 Screw, any head
B09 1 B09_M5x35 M5x35 Screw, any head
B10 2 B10_M4x8_flathat M4x8 Screw, flat head
B11 13 B11_M4x10_flathat M4x10 Screw, any head
B12 1 B12_M3x30 M3x30 Screw, any head
B13 32 B13_M3x12 M3x12 Screw, any head
B14 6 B14_M3x8 M3x8 Screw, flat head
B15 2 B15_M3_washer M3 Washer
B17 2 B17_M2x8_flathat M2x8 Screw, flat head

Parts to print

Part Number Quantity Part Name Description
M01 1 M01_Base Base Plate of the device
M02 1 M02_gear_a Gear a
M03 1 M03_gear_b1 Gear b1
M04 1 M04_gear_b2 Gear b2
M05 1 M05_gear_c1 Gear c1
M06 1 M06_gear_c2 Gear c2
M07 1 M07_gear_d1 Gear d1
M08 1 M08_gear_d2 Gear d2
M09 1 M09_gear_e Gear e
M10 4 M10_Bearing_cap_M5 Cap to screw in M5 bolt
M11 1 M11_Motor_arm Arm to swivel the stepper motor
M12 1 M12_Motor_mount Part to mount the stepper motor
M13 1 M13_mount_stand_gears_d Connects base with d-gear mount
M14 1 M14_mount_arm_gears_d Holds in place bearing of d-gears
M15 1 M15_e_bearing_adapter Standoff to mount minute handle to gear
M16 9 M16_WF_Holder Holds the Watchface in place
M17 3 M17_WF_clamp Watchface Mounting gear
M18 1 M18_WF_TRBR_clamp Clamp to fix watchface sub-parts
M19a 1 M19CW_c_Watchface_BR Watchface top right
M19b 1 M19CW_a_Watchface_TL Watchface botton right
M19c 1 M19CW_d_Watchface_BL Watchface bottom left
M19d 1 M19CW_b_Watchface_TR Watchface top left
M20 1 M20_Battery_Holder_Mount Mouting Point for PCBs and Batteries
M21 1 M21_PCB_mount_Arduino Mount for the Arduino nano
M22 1 M22_PCB_mount_RTC_Stepperdriver Mount for RTC and Stepperdriver
M23 1 M23_Handle_h Hour Handle
M24 1 M24_Handle_m Minute Handle
M25 1 M25_Wall_mount Wall Hanger
M26 1 M26_Desk_Stand_Left Desk Stand Left
M27 1 M27_Desk_Stand_Right Desk Stand Right
M28 1 M28_Cable_clamp Strain relief for USB cable

Parts which can be printed together in one operation:

  • M02_M03_M04_M06_M07_M08_M09
  • M10_M12_M13_M14_M15_M20_M21_M22
  • M16_M17_M18

Additional parts

  • USB Cable to power the clock (USB 2.0 is sufficient)
  • USB Charger
  • maybe two small felt pads to not scratch the wall painting when wall mounting
    The current draw is less than 500mA so any USB charger should work

Prerequisites to build this clock:

  • Soldering iron
  • Basic electronics skills to wire everything up
  • Knowledge on how to flash an Arduino with the provided code
  • M3, M4 and M5 thread cutters
  • Small wires to interconnect the electronic components
  • Pliers and scalpel or small box cutter to cut PCB trace of stepper motor (see Assembly Note 1)
  • Small flat head screwdriver and Multimeter to adjust motor current

Assembly

I created an animation which shows step by step how to assemble the clock. It is quite fast paced, just pause it at every step. In the video there are a few callouts to Assembly notes, these are covered here:

Assembly Note 1:

Stepper Motor Modification:
To make the clock as quiet as possible the normally unipolar stepper motor 28BYJ-48 ULN2003 is modified to be bipolar. João Brázio from the website Ardufocus shows how to do it. Basically you want to cut a single PCB trace (check with multimeter afterwards that the trace is cut)
https://ardufocus.com/howto/28byj-48-bipolar-hw-mod/

You can remove the end of the cable with the connector, we don’t need it, as well as the red cable in its entirety.

Assembly Note 2:

Wire up Arduino, Stepper driver and stepper motor.

Face the Arduino with its USB plug upwards (as in the video) and face the motor connections of the silent step stick in the direction of the stepper motor (M1A .. M2B). Connect the wires as shown in the wiring diagram:

Arduino Stepper Driver Stepper Motor
D11 EN
D12 DIR
D13 STEP
3V3 VIO
5V VM
GND GND near VM
M2B Dark Yellow
M2A Pink
M1A Bright Yellow
M1B Blue

Optionally you can remove the small resistor besides the red pwr LED so that the Arduino does not glow in the dark (recommended).

Assembly Note 3:

Wire up the RTC:
First, if you bought the cheap AZDelivery RTC DS3231 like me with a battery instead of an rechargeable battery you want to remove the diode between the IC and the four-pin connector. A forced charging with this diode of a non-rechargeable battery is a fire hazard.
We have to cut off the six-pin pinheader because the RTC would otherwise be too tall to fit under the clock face. Remove the battery while doing so to prevent accidental shortcuts. Plug the battery back in after removing the pinheader.

Now you can wire up the RTC:

Arduino Stepper Driver RTC
D2 SQW
A4 SDA
A5 SCL
GND near VIO GND
VIO VCC

Optionally you can remove the small resistor besides the red pwr LED so that the RTC does not glow in the dark (recommended).

Now is also a good time to flash the Arduino with the provided firmware:
https://github.com/mariuste/SilentWallandDeskClock

Shout-outs:

I want to thank Nico Schlueter for providing the awesome free gear making plugin “Helical Gears Plus” for Fusion 360. I created all gears in this design with it:
https://apps.autodesk.com/FUSION/en/Detail/Index?id=1259509007239787473&os=Win64&appLang=en

For preparing the release of this design I used the Fusion 360 Plugin Bommer by Jesse Rosakia and James Ray extensively. As the name implies it is very useful to create semi complex Bills of Material which allowed me to track my progress in various stages of the design.

To safe some time I used the following libraries in my code. They are available in the Arduino library manager
“StepperDriver” by Laurentiu Badea v1.3.1

“DS3231” by Andrew Wickert, Eric Ayars, Jean-Claude Wippler, Northern Widget LLC v1.0.7

Print Settings

Printer: Prusa Mini
Rafts: No
Supports: No
Resolution: 200
Infill: 20
Filament brand: Prusament
Filament color: Galaxy black, Pineapple Yellow, Orange
Filament material: PLA, PETG

Credits:

mariust

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File File size
zip Silent+Wall+and+Desk+Clock 11 MB

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