Week 08

Electronic production

• Group homework:
  • Characterize thedesign rules for your internal PCB production process: document your machine configuration.
  • Document the workflow for sending a printed circuit board to a board factory.
  • Document your work on the group work page and reflect on what you learned on your individual page.
• Individual task:
  • Build and test a microcontroller development board that you've designed.

Group Objective

During this week, the complete electronic production process was developed, from the design of the PCB to its manufacture, assembly and functional validation. The main focus was the creation of a board compatible with the XIAO ESP32-C3 microcontroller, comprising both the digital flow and the physical manufacturing process.

Likewise, it was sought to characterize and understand the design rules and the PCB production flow through the use of digital manufacturing tools, documenting the configuration of the Roland SRM-20 machine, the milling parameters and the file preparation process for internal and industrial production, in order to analyze how each configuration influences the quality, precision and final performance of the electronic board.

Link to the group assignment https://fabacademy.org/2026/labs/lima/Weeks/Week8/Week8.html

Learning Achieved

Through the group assignment, I learned how the PCB production process works, from machine configuration to board fabrication. I understood the importance of calibration, milling parameters, tool selection, and file preparation to achieve accurate and reliable results. I also learned the workflow for both in-house PCB manufacturing and industrial board production, improving my understanding of electronic fabrication processes.

Individual Assignment

Individual Goal

Fabricate, assemble and test a development board based on the XIAO ESP32-C3 microcontroller, applying the complete electronic production flow from toolpath generation in Mods Project to milling, soldering and functional validation of the PCB, to understand the integration between digital design, physical manufacturing and programming of electronic systems.

• Configuration of theMonofab SRM-20 milling machine
• UsingProject Mods
• PCB Manufacturing Parameters
• Flow for industrial production

My Process

SRM-20 Machine Configuration

The Roland Monofab SRM-20 milling machine, a precision machine for PCB prototyping, was used.

Initial setup in Mods:

• Program Selection:
  Roland → SRM-20 → PCB PNG
• Upload the PNG file of the design
• Tool Selection:
  • Traces: 1/64 cutter
  • Outline: 1/32 cutter

Key learning:

An error in the port or flow control prevents the connection to the machine.
Digital configuration is first validated before physical failures are assumed.

Milling with software modifications

Step 1

I downloaded the image in PNG format corresponding to the design of the Card, which I would use to perform the milling.

Step 2

I entered the modsproject.org page and right-click opened the program.

Step 3

I selected "Open Program".

Step 4

I chose the "Mill PCB 2D" option to set up the milling of the board.

Step 5

The interface appeared where I had to configure all the technical parameters.

Step 6

Within the program I did the following:

• I uploaded the PNG image of the design.
• I selected the 1/64 thin milling cutter for milling the tracks.
• I turned on the output to generate the cut file.
• I set up the X, Y, and Z axes to define the starting point.
• I clicked "Calculate" to generate the .rml file that I would later load onto the SRM-20.

4. Trajectory Generation

The toolpaths were generated from the PNG design.

Parameters used:

• Cutting depth: 0.012 inches
• Offset: 1 or more passes
• Tool: 1/64 for tracks

This defines how the machine will remove the copper.

Machine calibration

Calibration was one of the most critical steps.

🔧 Process:

X/Y axis:

• Manual positioning
• Definition of Origin

Z-axis:

• Manual cutter adjustment
• Slight surface contact

If the burr goes too low → breaks If it is high → does not cut

PCB Milling

The milling was carried out in two stages:

🔧 Process:

1. Track Milling (1/64)
2. Tool Change
3. Contour Milling (1/32)

🔧 Considerations:

• Constant monitoring
• Avoid vibrations
• Verify material fixation

. Assembly & Welding

Manual welding of the components was performed.

Despite not being perfect, the welding was functional.

In the Arduino IDE, I go to tools and select the board and the XIAO processor

• The crystal I used for the PCB is 20 MHz, so I select an external 20 MHz relog.

• Next, I chose the "Xiao SP 32", for this I chose the Programmer.

• Now I use a program that uses a button connected to PA2 (pin11) to turn on an LED connected to PA3 (pin10), based on the PCB designed.
• The next step is to write the program "Hi Attiny44" on the microcontroller. If all goes well, it will be a success.

HERO SHOT

Problems and solutions

Problem 1: PCB Traces Were Not Milling Properly

Solution: The depth of cut was adjusted and the levelness of the machine was checked before milling again.

Problem 2: Some components didn't fit properly soldered

Solution: A finer tip was used on the soldering iron and flux was applied to improve the quality of the welds.

Problem 3: The board was not recognized by the computer

Solution:
Revised USB connections and fixed soldering errors on power and communication pins.

Learning achieved

During this week, it was possible to understand the complete flow of electronic production, integrating the stages of design, manufacture and validation of a functional PCB. Learned how to prepare fabrication files using Mods Project and how to correctly configure the Roland SRM-20 milling machine for track and contour machining.

Likewise, the importance of the calibration of the axes, especially the Z-axis, was understood, since small errors directly affect the quality of the milling and the operation of the plate. Skills were also strengthened in SMD component welding, handling of electronic tools, and verification of electrical connections.

On a practical level, it was possible to manufacture and test a board compatible with the XIAO ESP32-C3 microcontroller, validating its operation through programming in Arduino IDE. This experience allowed us to understand the relationship between digital design, physical manufacturing and embedded programming within the electronic development process.

In addition, it was learned that electronic production is an iterative process where accuracy, correct parameter configuration and error resolution are essential to obtain functional and reliable results.

📋 Check-off List

1. ✅ Linked to the group assignment page?

Yes.

2. Yes, the link to the group work was included and the characterization of the PCB production process and configuration of the Roland SRM-20 was documented. ✅ Did you document how you created the toolpath?

Yes.

3. Yes, the use of Mods Project, PNG file upload, cutter selection (1/64 and 1/32), parameter settings, and generation of .rml files and cutting paths were explained. ✅ Did you document how you fabricated (ground, filled, welded) the board?

Yes.

4. Yes, the complete process of track and contour milling, axis calibration, tool change, and assembly using SMD welding was described. ✅ Documented that your dashboard is functional?

Yes, the operation was validated by programming the XIAO ESP32-C3 in the Arduino IDE and executing a code where a button controls an LED.

❓ Frequently Asked Questions

1. Do I have to include NC files?

Answer:
I don't need to include NC files in my submission. In my case, I documented the entire PCB fabrication flow using Mods Project and the Roland SRM-20 milling machine, including the generation of cut files (.rml) and milling settings for traces and contours. The important thing was to demonstrate the entire process, not attach machine files.

2. How do I know if my hob is working properly?

Answer:
I can check that my board is working properly by loading a program on the XIAO ESP32-C3 microcontroller. In my case, I used a simple code where a push button controls an LED connected to the PCB. If the LED responds to the button and the program runs without errors from the Arduino IDE, then the board is working correctly.

3. Do I have to send a printed circuit board to a board factory if I don't need one?

Answer:
You don't need to send the PCB to a factory. However, I do have to document the whole process as if it were going to be produced industrially. In my work I showed everything from the design in KiCad to the generation of manufacturing files, the milling in the SRM-20, the assembly and the final test of operation. The focus is on demonstrating the complete flow of electronic production.

4. What settings do I need to document?

Answer:
I must document all the parameters that directly affect the final result of machining and assembly. In my case I included:

• In CNC milling (SRM-20):
  • Tools used (1/64 for tracks and 1/32 for outline)
  • Cutting depth
  • Number of passes (offsets)
  • X, Y, and Z-axis calibration
  • Working Speed (defined in Mods)
• In PCB manufacturing:
  • Flow Settings in Mods Project
  • Generating .rml files
  • Bed leveling and Z-axis adjustment
  • In assembly:
    • Flux Usage, Soldering Iron Temperature, and Tin Type
    • Soldering Techniques for SMD Components

    These adjustments were key to obtaining a functional PCB and avoiding errors during milling and soldering.