Triaxial Numechron Clock

prusaprinters

A mechanical digital clock with three digit wheels on different axes (X, Y and Z) from each other.Visually crazy but practicalDriven by a single stepper motorAll parts are designed within 180 x 180mmEasy time adjustment by manual (physical) operationHigh visibility with large digit charactersNov. 6, 2023 : I noticed that I uploaded wrong .ino file (program) that does not match to the photo of circuitry. I uploaded correct version.VideoHow to makeNecessary partsAssortment of 2mm tapping screws28BYJ-48 geared stepper motor and driver board comes withAny microcontroller (Arduino, ESP32, Raspberry Pi, etc.)PrintPrint all parts with supplied posture.Support structure is not needed except "10min-rotor.stl".Remove debris and blobs well, especially around the axis and sliding surfaces.Use the material in different color for digit texts.Digit parts are difficult to distinguish each other. Especially, "6" and "9" are confusing (but the shape is not identical). Curvature of back surface of the digits are different for hour, 1s and 10s place of minutes.Attach digits to the rotorsYou can attach digits to the rotors with glues (ex. superglue) or plastic welding.I recommend the welding method because it is easy, fast and beautiful. Use temperature control soldering iron to set it to low temp (250 centigrade) to avoid the fume of the material.Holes on the rotors are arranged for each digit. Please confirm whether the position is correct or not before fix the digits.Assembly of the right frame unitAttach "int-gear.stl" and "hour-driver.stl" to the hole of the "frame-right.stl".Attach the two adjustors to the frame.Attach "1min-rotor.stl" to the frame using "1min-holder-1.stl" and "1min-holder-2.stl".Please make sure that all parts rotate smoothly.Assembly of the 10s place of minutesAssemble "10min-driver.stl" and "10min-rotor.stl". The direction of the parts are regulated by the trapezoidal shape of the keys between connecting parts.Align two markers on the gears facing each other.Please make sure that the 10min-adujustor is put on the 10min driver.Assembly of the remaining partsAttach the stepper motor and "motor-gear.stl".Assemble the hour rotor with left side frame.Attach the remaining parts with screws.CircuitryUse your favorite microcontroller to drive the stepper motor.Sample program (numechron.ino) is for Arduino. Otherwise, drive the motor 1536 steps per minute.Housing of the arduino nano and driver board can be found at https://www.thingiverse.com/thing:5145523If the motor rotates to the opposite direction, change the source code fromint port[4] = {7, 6, 5, 4};toint port[4] = {4, 5, 6, 7};Operation (time adjustment)Hour and 10min rotors can be rotated by your hand. Forward rotation only .The program for Arduino drives the motor immediately after reset. Therefore, you can proceed 1 minute by reset button .Alignment of the 1min rotor can be also possible by the reset button. Press the reset button when the digit comes to the correct position.80% Shrunk VersionPrint all parts in 80% scale.Use modified models (download from Instructables) for "frame-base.stl" and “motor-gear.stl” because the stepper motor is not shrank. These models should be also shrank to 80% scale when printing.If "1min-holder-1.stl" is too thin, use "1min-holder-1-thicker.stl" instead.note : Since the number of optional files increase, it might be now confusing to add them here. So please download optional files from step 8 and 9 at Instructables. Tuning of the Clock SpeedThe clock of Arduino is not as accurate as common clocks. Please tune the value to improve the accuracy of your clock.Measure the error of your clock. Adjust your clock correctly and wait for 24 hours, then Measure the error of your clock in seconds.Input the error value (in second) for the value named COMPENSATION_SECONDS at line #3 in the source code. If your clock gains (too fast), enter positive value, and vise versa.Compile and flash your program to your microcontroller.Update historyNov. 4, 2023 : “motor-gear.stl” is modified to add a 1mm collar, for the case of loose fit to the motor axisNov. 18, 2023 : Code is improved to directly input the compensation value of clock speed in seconds.Nov. 18, 2023 : Optional files are deleted to avoid confusion. Please download them from Instructables.Category: Gadgets