Electronics Production

🐲 1. Project Overview

For this week’s production assignment, I milled the circuit board I designed earlier during Electronics Design week. The board is built around the XIAO ESP32C3 microcontroller and includes multiple SMD Grove connectors, which makes it easy to plug in different input and output devices using Grove cables.

I also added a pushbutton and a built-in LED directly on the PCB. This makes quick code testing a lot easier without needing to wire up anything extra. The board was specifically designed to support the kind of input/output setup I’ll need for my final project — so producing it this week was an important step toward bringing the full idea to life.

🐲 2. Toolpath Generation

To get started with milling, I used the circuit I fully designed in KiCad during Electronics Design week. All the preparation steps—like schematic and footprint linking—were already covered back then, so now I just needed to get everything ready for production.

I exported the design as SVG files, since SVGs are easy to handle in multiple software tools. Specifically, I created two separate SVG files: one for the circuit trace paths, and another for the board outline cut. I used Inkscape to cleanly separate the layers and export each part individually.

🧰 Using modsproject.org for Toolpath Generation

I used modsproject.org to generate the actual milling paths for the Roland SRM-20 machine in our lab. Here’s how it went:

Trace paths: V-bit with 30° angle
Outline cut: 1/16" flat endmill

It’s important to know what bits are available in your lab before generating the toolpaths. If you're unsure, ask your instructor or search online for recommended bit sizes for PCB milling.

🔧 Steps for Generating Toolpaths

Open modsproject → Programs → Open program → Roland → SRM-20 Mill → mill 2D PCB

Upload the inner trace SVG, make sure the dimensions match the outline SVG exactly
Check Invert because traces are milled around the lines

Enter V-bit parameters manually, click "Send calculated settings"

Set low speed and set X/Y/Z to 0 (to be set manually later)

Click Calculate to generate the .rml toolpath, then View to inspect

Repeat the same for the outline SVG:

Don't invert this one

Use 1.59mm diameter (1/16") and appropriate cut depths

🐲 3. Milling the Board

I used an FR4 board because it's sturdier and longer-lasting than FR1. My bit choices were:

30° V-bit for inner traces
1/16" flat bit for the outline

To set up the Roland SRM-20:

Applied double-sided tape to secure the board

Manually set X, Y, Z axes to 0 near the bottom-left corner

Opened the .rml files and started milling!

🐲 4. Stuffing & Soldering

Soldering went great. I used a TENMA Digital Solder Station and HiFlo Rosin-Activated Core Solder Wire. Here are the components I soldered:

Component	Value/Type	Notes
Microcontroller	XIAO ESP32C3	Through-hole headers
Grove Connectors	SMD 4-pin	Plug-and-play
Resistors	0Ω, 100Ω, 10kΩ	Bridging, pull-up
LED	Green (SMD)	Feedback
Button	SMD push-button	Input testing

🐲 5. Debugging and Testing

I used a multimeter for continuity testing before powering the board. I checked all the power lines, the button, and LED paths.

Then I flashed the following code to test the LED and button:


#define LED_PIN 10
#define BUTTON_PIN 0

void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
}

void loop() {
  if (digitalRead(BUTTON_PIN) == LOW) {
    digitalWrite(LED_PIN, HIGH);
  } else {
    digitalWrite(LED_PIN, LOW);
  }
}

The test was successful — pressing the button turned the LED on!

🐲 6. Problems & Fixes

Nothing was wrong with the soldering or wiring, but I realized I should’ve matched my trace widths more closely to the bit size. Milling took a lot longer than expected because the machine had to trace each line multiple times at slow speed. Next time, I’ll:

Match trace width to tool diameter
Set more efficient cut depths and speeds
Avoid unnecessary multi-pass paths

🐲 7. Final Files

✅ grove_shield.kicad_sch – Schematic from KiCad
✅ grove_shield.kicad_pcb – PCB layout
✅ inner_mill.svg – For trace milling
✅ outline_cut.svg – For outline cutting
✅ inner_path.rml – Generated toolpath for traces
✅ outline_path.rml – Toolpath for cutting the board
✅ led_button_test.ino – Test code
✅ Grove_1x04-90Degree.kicad_mod – Custom SMD Grove connector footprint

Everything is documented and organized for easy reuse, sharing, or improvement.