Electronic
Production

At Fab Lab Ulima we use the Roland Modela Pro II MDX-540, a precision CNC milling machine used for rapid prototyping through subtractive manufacturing processes. Subtractive manufacturing works by removing material from a solid surface using cutting tools, following paths generated by digital fabrication software.

The machine allows us to:

Different milling tools are used depending on the type of operation during the PCB fabrication process.

Different materials can be used to fabricate printed circuit boards, each with different mechanical and thermal properties.

For this process, we used the Roland Modela Pro MDX-540 to machine the PCB following a precise step-by-step workflow to ensure accurate engraving and clean board cutting.

During Week 6, I designed my first PCB — but it wasn't good enough. For the Week 8 assignment, I decided to completely redesign the board. In the first version, I integrated many components directly on the PCB. After analyzing the circuit more carefully, I realized that several of these components could instead be connected using available free pins through headers.

Including them directly on the board was unnecessary and caused copper traces to cross each other, which could lead to fabrication problems during the milling process.

Before & After

Before — Version 1 (Week 6)

After — Redesigned (Week 8)

To redesign the PCB, I analyzed all the components and classified them according to their type and signal. The microcontroller used is the XIAO ESP32.

Pin Requirement Summary

The same procedure was followed to create three SMD pin connectors: 1×3, 1×4 and 1×6. Each one went through the same four steps described below.

1

Configure Component Properties

The component editor opens where the Name and Prefix fields are filled in on the right panel. The Añadir símbolo button is pressed to link an existing symbol and Nueva huella to create the footprint.

2

Verify Symbol and Associate the Footprint

The left panel shows the component structure in three levels: component, symbol and footprint. Each part can be edited separately by clicking on it.

3

Edit the Footprint in the Footprint Editor

Fusion 360 automatically switches to the HUELLA tab, where the 6 SMD pads are visible, numbered 1 to 6, vertically aligned on the top copper layer.

4

Link Pins to Pads

The Connect 1X06SMD window opens showing three columns: Pin, Platform and Connection. The Conectar button is pressed six times — once per pin — to complete the mapping. Finally Aceptar is pressed and the component is ready to use in the PCB design.

In Autodesk Fusion 360, go to the Manufacture tab and select the CAM Processor. From there, click on "Generate Gerber Files".

Save the files in an empty folder. Automatically, all the necessary files are generated. The most important ones are:

Since the PCB design was created in Autodesk Fusion 360, the files were exported as Gerber files. For the individual assignment, I used FlatCAM to generate the G-code for the CNC milling machine.

Then, I simulated the G-code using NC Viewer at ncviewer.com, which allowed me to visualize the cutting layers and verify that there were no extra paths or unwanted dots in the design.

In the ceramic test, the traces ended up being too thin. This happened because we used a very sharp milling bit, and during the Z-axis calibration, since the material is brittle, the tool went slightly deeper than expected and removed more material from the traces. Because of this, some of the paths became too narrow, which could affect the connectivity of the circuit.

The fiberglass test had a better finish with cleaner, more consistent trace widths.

After milling, the components were soldered onto the board.

I used a multimeter to check the continuity of the traces and verify that the soldering was done correctly before uploading and testing the programming code from Week 4.

The following code was uploaded to the board to test the basic LED + button functionality:

// Pin definitions
#define LED_PIN  8   // D8 = GPIO8
#define BTN_PIN  9   // D9 = GPIO9

bool ledState = false;      // Current LED state
bool lastBtnState = HIGH;   // Last button state

void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(BTN_PIN, INPUT);
  digitalWrite(LED_PIN, LOW);
}

void loop() {
  bool currentBtnState = digitalRead(BTN_PIN);

  // Detect falling edge (button PRESS)
  if (lastBtnState == HIGH && currentBtnState == LOW) {
    ledState = !ledState;                    // Toggle state
    digitalWrite(LED_PIN, ledState);
    delay(50);  // Debounce
  }

  lastBtnState = currentBtnState;
}