• Using a solder paste dispensing needle, we apply solder paste to each SMD component pad to begin the PCB assembly process.
• Next, we added all the SMD components in their place using a ESD Tweeser.
• The circuit was then placed on the Reflow Hotplate, which heats the PCB from below to the solder paste melting temperature. All SMD components are connected to their pads as soon as the PCB reaches the solder paste melting temperature, which is typically 200° C.
• Turning the Board over, we started the THT Components assembly by first placing the Lithium ion cell holder using a solder iron.
• Next, we solder the pads to secure the other THT components, such as the switch, JST connection, and USB Type C port, in their proper locations.

We utilized a 3.7V 2000mAh Li-ion cell as the power supply, which was connected to the lithium cell holder in the proper polarity.

After pressing the ON button and the device turns on, we measure the output voltage with a multimeter and observe that it is 5.1V, indicating that the circuit is working.

We attached an XIAO M0 microcontroller to the circuit and uploaded the code below to see if it worked or not.

The JST wire connector for the motor is then inserted into the circuit JST connector.

const int motorPin1 = 0; // Pin connected to H-bridge input 1
const int motorPin2 = 1; // Pin connected to H-bridge input 2
const int ledCW = 3; // Pin connected to LED for clockwise direction
const int ledCCW = 4; // Pin connected to LED for counterclockwise direction
void setup() {
pinMode(motorPin1, OUTPUT);
pinMode(motorPin2, OUTPUT);
pinMode(ledCW, OUTPUT);
pinMode(ledCCW, OUTPUT);
}
void loop() {
// Turn motor ON in one direction (clockwise)
digitalWrite(motorPin1, HIGH);
digitalWrite(motorPin2, LOW);
digitalWrite(ledCW, HIGH); // Turn on CW LED
digitalWrite(ledCCW, LOW); // Turn off CCW LED
delay(3000); // Wait for 3 seconds
// Change direction (counterclockwise)
digitalWrite(motorPin1, LOW);
digitalWrite(motorPin2, HIGH);
digitalWrite(ledCW, LOW); // Turn off CW LED
digitalWrite(ledCCW, HIGH); // Turn on CCW LED
delay(3000); // Wait for 3 seconds
}

This code controls an H-bridge motor driver to turn a motor in clockwise and counterclockwise directions for 3 seconds each. LEDs indicate the direction of the motor's rotation, with ledCW lighting up for clockwise and ledCCW lighting up for counterclockwise.

The system is turned on and the motor begins to spin in a single direction after the power button is pressed. After three seconds, it reverses course for an additional three seconds, repeating the cycle.

Now that the circuit is operational, we may proceed with the gearbox body assembly procedure.

• Let us begin with the midsection assembly, which starts with the DC gear motor being inserted into the Gear Motor Holder part.
• The motor stopper, a tiny part that holds the motor in place, is then used. It is tightened with two M2 screws on the midsection.
• The Gear A is now attached to the motor shaft.

• Now that we have the gear assembly, we put the first set of gears—which contained gears A, B, and C—into position first, followed by set two, which included gears D and E.
• We install the top layer part, which has openings for the input and output gears as well as for Gear B, to secure all of the gears in place.
• To keep Gear B in place, we fastened it with an M6 bolt.
• We attached the 3D printed spacers from the four sides, which would be positioned between the middle and top layers. M6 bolts were used to put them in place.

On the Bottom layer, we position the circuit and secure it in place using Three M2 Screws

• First, we connect the JST wire connector of the DC motor to the JST connector on the circuit to begin combining the Mid Gear assembly and the bottom layer.
• After attaching the 3D-printed spacers to the M6 bolts, we positioned the bottom layer and used four M6 nuts to secure it.
• The gearbox assembly is finished.

The finished product of this build is a functional Gearbox 3D. Made from scratch, we used only 3D-printed gears in this build, and since there is tolerance between the gear and the body, they operate smoothly. No bearings were needed. Bearings for individual gears can be used to smooth things out and reduce the frictional losses, but that is a topic for a later update.

For now this project is working and can be totally powered by the onboard lithium cell.

What we will be doing with this gearbox is mounting a kinetic sculpture to the top of it, which will be mounted on a wall. Kinetic sculptures are works of art that use motion and balance to create dynamic and eye-catching pieces. In this case, we are using two blades with a unique pattern; two of them are ready, and one is mirrored of the other.

One blade will be attached to the clockwise rotating shaft, and another blade will be placed to the counterclockwise rotating shaft. Two blades moving in opposite directions provide an intriguing pattern that is visually euphoric.

The next project will be a brief tutorial on how to construct a kinetic sculpture using the gearbox built in this article.

For now, this project is finished and needed no further revision.

All the details regarding this project, including files, are attached, which you can download.

Leave a comment if you need any help regarding this project. This is it for today, folks.

Thanks to Seeed Studio Fusion for supporting this project.

You guys can check them out if you need great PCB and stencil service for less cost and great quality.

And I'll be back with a new project pretty soon!