Rock tumbler with timer

thingiverse

I was thinking of printing JT3D's Affordable Rock Tumbler but wanted a little more control so I decided to build one based on an Arduino. The main thing is the stepper motor and using its rpm and steps/revolution to get an approximation for how long it will run. ### Assembly You should be able to put it together by just looking at the pictures. One thing I decided to do is put bearings in the right side wheels and let them move freely. The drive side is fixed and the bearings sit in the frame. There's a replacement STL included for the right side of the frame if you decide to go that way. ### Barrel Insert The insert for the barrel is 153mm wide. I bought some anti-slip mat that I hot glued to the inside and then just put some glue on the edges and forced it in. I use a bunch of nails and rivets as my polishing media. ### Arduino Wiring I used an Arduino Uno and a Perma-Proto board to mount the electronics on. My power adapter is 9V 2A so there's a voltage regulator between the power cord and motor to get it down to 4.83V. I couldn't find the correct representations for the components so you'll have to check each part for how to connect them. Code --------------------- ```c #include <Button.h> #include <Stepper.h> #include <U8glib.h> const int potPin = A0; Button startButton(3); const int steps = 200; const int rpm = 80; Stepper stepper(steps, 4, 5, 6, 7); U8GLIB_SSD1306_64X48 oled(U8G_I2C_OPT_NONE); enum status { stopped, started }; status tumblerStatus; long stepsLeft; void setup() { stepper.setSpeed(rpm); startButton.begin(); tumblerStatus = stopped; stepsLeft = 0; } void loop() { oled.firstPage(); if (tumblerStatus == stopped) { do { drawStartPage(); } while (oled.nextPage()); } if (startButton.read() == LOW && tumblerStatus != started) { tumblerStatus = started; stepsLeft = getTotalSteps(); } else if (startButton.read() == HIGH && tumblerStatus == started) { tumblerStatus = stopped; stepsLeft = 0; } if (tumblerStatus == started) { if (stepsLeft > 0) { stepper.step(-1); stepsLeft--; } else { oled.clearDisplay(); oled.setFont(u8g_font_helvB12); oled.drawStr(10, 30, "Time's Up!"); delay(2000); tumblerStatus = stopped; } } } unsigned long getTotalSteps() { unsigned long potValue = getHoursToRun(); unsigned long stepsToRun = potValue * 60 * steps * rpm; return stepsToRun; } long getHoursToRun() { unsigned long potValue = analogRead(potPin); unsigned long value = map(potValue, 0, 1023, 1, 24); return value; } void drawStartPage() { oled.setFont(u8g_font_04b_03); drawLine("Rock Tumbler", 8); drawLine("v1.0", 16); oled.setFont(u8g_font_helvB08); drawLine("Run for", 28); char time[5]; sprintf(time, "%dh", getHoursToRun()); oled.setFont(u8g_font_helvB12); drawLine(time, 44); } void drawLine(char text[], int line) { int x = (oled.getWidth() - oled.getStrWidth(text)) / 2; oled.drawStr(x, line, text); } ``` Hardware --------------------- I've put what I used in parentheses: - Arduino + wires (Arduino Uno rev. 3) - 64x48 OLED (OLED Shield for WeMos D1 mini) - Stepper Motor driver (Adafruit TB6612) - Perma-Proto board (Adafruit Perma-Proto Half-sized, 82mm x 55mm) - Voltage regulator (Luxorparts, 4.5-28 V to 0.8-20 V. Based on MP1584) - Power Adapter (9V, 2A) - Button - Potentiometer - Power switch - 8mm Threaded rods - 8mm Nuts, lock nuts, lock washers - Bearings, 22mm x 7mm M8 - O-rings for the wheels Video --------------------- https://youtu.be/vNP2_rVvvXg