Electronics Production

Week 8 - Group Assignment

At Fab Lab Puebla, our in-house PCB production workflow is supported by two specialized machines: the Roland MonoFab SRM-20, a high-precision compact milling machine, and the xTool F1 Ultra, a dual-source fiber and diode laser system. We utilize these tools to characterize and compare mechanical milling versus laser ablation, allowing us to establish the specific design rules and tolerances required for reliable circuit fabrication.

Roland SRM-20

The Roland SRM-20 is a compact CNC desktop milling machine used for prototyping, PCB milling, and small mechanical parts. It removes material using rotating cutting tools.

Main Technical Characteristics

Work area: 203.2 × 152.4 × 60.5 mm
Table size: 232.2 × 156.6 mm
Spindle speed: 3,000 – 7,000 rpm
Feed rate: 6 – 1800 mm/min
Mechanical resolution:~0.000998 mm/step
Max workpiece weight:2 kg
Control interface:USB (RML-1 or NC code)

PCB Milling Characteristics (SRM-20)

Fabrication method: Mechanical milling that removes copper from a copper-clad board using rotating cutting tools.
PCB types supported: Single-sided and double-sided printed circuit boards.
Typical substrate materials: FR-1 (phenolic paper laminate) and FR-4 (fiberglass laminate).
Trace resolution: Usually between 0.15 mm and 0.3 mm.
Tool types used: V-engraving bits, End mills, and Micro drill bits.
Spindle speed: Typically 5,000–7,000 rpm.
Cutting depth: Usually 0.05–0.15 mm.

Compatible Materials — SRM-20

Material	Description	Common Uses
Modeling Wax	Soft machinable wax	Jewelry molds, casting models
Chemical Wood	Dense resin-based board	Functional prototypes
Acrylic (PMMA)	Transparent thermoplastic	Enclosures, panels
PCB copper boards	Copper-clad laminates	Electronic circuit boards

xTool F1 Ultra

The xTool F1 Ultra is a dual-laser engraving and cutting system combining a 20 W fiber laser and a 20 W diode laser for processing both metals and non-metals.

Main Technical Characteristics

Laser type: 20 W Fiber + 20 W Diode
Working area: 220 × 220 mm (up to 500 mm with conveyor)
Max engraving speed:up to 10,000 mm/s
Spot size: >0.03 × 0.03 mm (fiber), 0.08 × 0.1 mm (diode)
Motion accuracy:~0.00482 mm
Connectivity:USB / Wi-Fi

Laser Processing Characteristics (F1 Ultra)

Dual-laser system: Combines a 20 W fiber laser and a 20 W diode laser.
Fiber laser (~1064 nm): Optimized for metal engraving and marking.
Diode laser (~455 nm): Designed for non-metal materials.
High engraving speed: Up to 10,000 mm/s.
Camera positioning: Built-in camera for visual alignment.
Automatic focusing: Ensures optimal engraving quality.

Compatible Materials — xTool F1 Ultra

Material	Description	Common Uses
Stainless Steel	Corrosion-resistant metal	Tags, industrial marking
Aluminum	Lightweight metal	Electronics housings
Wood / Leather	Organic / Natural material	Crafts, accessories
Ceramics / Stone	Hard brittle material	Decorative engraving

Safety Measures

Both machines incorporate specific safety systems to protect the operator from mechanical and radiation hazards.

Roland SRM-20 (Mechanical Safety)	xTool F1 Ultra (Laser Safety)
Protective enclosure: Prevents chips and debris from leaving the workspace. Safety interlock system: Automatically stops if the cover is opened. Dust containment: Reduces exposure to fine particles during milling. Secure mounting: Prevents tool breakage from material movement.	Enclosed laser housing: Prevents direct exposure to the beam. Filtering window: Special glass blocks harmful laser wavelengths. Air filtration: Removes smoke and fumes via ventilation. Flame detection: Stops automatically if fire risk is detected.

Typical Operating Parameters

Standard settings for common operations on both machines:

Machine	Parameter	Typical Value/Range
Roland SRM-20 (PCB Milling)	Tool diameter	0.1 – 0.4 mm
	Feed rate	100 – 250 mm/min
	Cut depth	0.05 – 0.15 mm
xTool F1 Ultra (Laser Engraving)	Laser power	10 – 100%
	Engraving speed	100 – 10,000 mm/s
	Passes	1 – 10 (material dependent)

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Note: These parameters depend on tool geometry, material type, and required precision.

Roland SRM-20 Workflow and Characterization

monoFab parts

Front cover: A protective cover that must stay closed during coordinate adjustment and the milling process. It features an automatic safety interlock that pauses the job immediately if the door is opened, ensuring operator safety.
Power button: This is the main power switch for the machine.
Spindle: The spindle head houses the motor and moves across multiple axes to mill the PCB. This is the component where the cutting tool is securely mounted.
Workbench: The workbench provides a stable surface for securing the PCB during milling operations.

Minimum Clearance and Width

We used Neil’s trace test file to define our machine's parameters. The top section measures clearance from 1 mil to 20 mil, while the bottom section tests track width in the same range.

Mods

To make our PNG files compatible with the Roland SRM-20, we need to convert them into .rml files. We use the Mods platform to process the images and generate the toolpaths required for the milling machine.

Program

To select the correct program, open the Programs menu on the upper-left. Scroll down to find the SRM-20 mill section and select "mill 2D PCB".

Workspace

This is our Mods workspace. Although it might look complex at first, it is very easy to use by following just a few simple steps.

Read PNG

First, we need to select our PNG or SVG file. Keep in mind that the program will preserve everything in white and mill away the areas marked in black. Make sure your design is correctly inverted before converting it to the .rml format.

PCB defaults

Next, you need to select the PCB defaults node. You can choose "mill traces (1/64)" for engraving, "mill outline (1/32)" for cutting the board's edge, or "mill traces (10 mil)" for drilling holes. In this case, we selected the first option for the engraving process.

Mill raster 2D

We need to set the tool diameter, cut depth, and the number of offsets. Once configured, we click "calculate" and then "view" to visualize the toolpath. This step is essential to ensure the tool will pass correctly through all the traces without leaving unwanted copper.

Speed and Origin Configuration

Next, we need to set the cutting speed and calibrate the machine’s position. It is crucial to set all coordinates (X, Y, and Z) to the 0 origin to ensure the milling process starts exactly at the designated origin point.

Save rml file

Finally, we must enable the (on/off) option. Once we click "calculate", the .rml file will be automatically generated and downloaded.

VPanel

To control the MonoFab, we use the VPane for SRM-20 software. This interface allow us to move the tool along the X, Y, and Z axes using the on-screen cursors. Once the tool is positioned at a suitable starting point on the material, we use the Set Origin Point function to define our coordinates. Additionally, the Cursor Step option controls the movement increment.

Cut

Once the origin for all three coordinates is correctly defined, we raise the tool to a safe height to prevent any collisions. Next, navigate to the Cut menu and select the .rml file. To start the milling process, simply press the Output button.

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Results

After running the clearance and width test files, these are the results obtained on the SRM-20. This test is crucial to determine the machine's resolution and the limits of the tool being used.

Applied Parameters:

Tool Diameter: 0.1 mm
Cut Depth: 0.1016 mm
Cut Speed: 4 mm/s

Fig 1. Minimum Clearance and Width - Results

XTool F1 Ultra Workflow and Characterization

XTool F1 Ultra parts

Safety Door: The machine includes a safety door for protection during operation.
Ports and Power: Here is the power button. It features multiple ports to link the machine to the control software and connect various attachments.
Emergency Stop: it is equipped with a emergency stop button to stop all activity instantly.
Control panel: It has a small panel to control the machine's activities.
Smoke Extractor: It has a smoke extractor to keep the air clean.

Main menu

To edit your documents and send the data to the machine, we use the xTool Studio software. This program allows you to import your designs, adjust settings, and control the laser's position.

Create a new project in the upper-right corner button (green button).

Connect

We must first link the machine. Make sure the USB cable is connected from your computer to the machine. In the top right menu, you will see the machine icon; click the link menu and connect to it.

Parameter Settings

Then, go to the Settings icon since we need to calibrate the machine before using it. Navigate to the Parameter Settings section and start the calibration for the IR Fiber and Blue Light Lasers.

Calibration

Follow the instructions provided by the calibration process. Place the paper in the center of the base plate.

Close the safety cover and press the green button on the machine's control panel. The lasers will then turn on and attempt to align with the crosses on the paper.

Coordinates

An image will appear showing what the machine recognized as the location of the crosses. You must ensure that the zero coordinates for both are centered on the crosses in the image. You can adjust them manually or use the auto-recognition feature.

Confirm

To see the changes made, press the Refresh button to confirm. Once you have verified that everything is correct, press Confirm to finish the process.

Upon lifting the safety cover, you must verify that the two lasers are perfectly aligned, with one positioned directly over the other. If they are not aligned, you must repeat the calibration process from the beginning.

Engrave Test

To test the laser's speed and power, we will perform an engraving test. First, ensure that the IR Fiber Laser is selected in the right-hand menu and that the engraving mode is set to unidirectional. You should also choose the number of passes you think are necessary, I set mine to 5. Then, go to the Shapes menu on the left and select any figure you want to use for the test.

Applications

Go to the Applications menu and select the Material Test Array option. From there, you will need to adjust the maximum and minimum values for both speed and power to create the test grid.

Automatic measurement

To position our grid correctly and ensure it fits on the material, you can use the Auto-measure and camera function located at the top. This feature provides a photo of your material, allowing you to place the design accurately within the workspace.

Design

To use a previously made design, we import our document. In this case, we also performed the minimum clearance and width tests. After selecting the design, several options will appear at the top to manipulate it; first, we must create a compound vector for our design.

minimum clearance and width tests

This is how the document looks once positioned on the image of the material. Remember that the laser will remove the areas marked in black and leave the white areas untouched. Based on our tests, these are the best parameters

Start process

Once everything is configured, we start the process. The software will display the path the laser will follow. Press Start, and it will prompt you to press the green button on the machine's control panel. Once the process is complete, it will be marked as finished, and you can lift the safety cover to retrieve your material.

Smoke extraction

Make sure the smoke extractor is turned on during the engraving process, as it will help keep the air clean by removing the smoke and fumes generated by the laser.

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Results

Here is the result for the Engrave Test.

Fig 2. Engrave Test

After running the clearance and width test files, these are the results obtained on the XTool.

Applied Parameters:

Laser type: IR Fiber
Power (%): 100
Speed (mm/s): 750
Passes: 10
Lines per cm: 300
Engraving mode: Unidirectional

Fig 3. Minimum Clearance and Width - Results

Comparison Between Both Machines

Feature	Roland SRM-20	xTool F1 Ultra
Fabrication method	CNC milling	Laser engraving/cutting
PCB capability	Yes (PCB milling)	Not ideal for PCB milling
Metal processing	Not supported	Yes
Waste produced	Chips and dust	Smoke and fumes
Typical use	PCB prototyping, small parts	Engraving, marking, laser cutting

PCB to a boardhouse

One assignment this week is to upload a PCB design to a board house, for which we use JLCPCB. For this step, remember that you must have a ZIP folder ready containing the Gerber files from your board design.

Select Order Now, and the menu will appear where you can upload your folder.

After you have uploaded your folder, you will see a preview of your board so you can confirm that everything is correct. It is important that the folder includes all the layers you want to appear on the PCB.

In this menu, we can customize our PCB by changing the base material, the thickness, the color, and many other parameters. We can also select the quantity of PCBs we want, with a minimum order of 5. For this project, I left the default parameters as they were appropriate for the design.

We add our order to the cart. Here, we can see the estimated cost and also modify the lead time, depending on whether we have minimum or maximum urgency for the boards to be ready.

Here you can select the shipping address, the shipping method, and finally submit the order.

After you have placed your order, you can log in to the website to track the manufacturing progress of your board. Once the PCB is finished, delivery typically takes between 5 to 7 business days, depending on the shipping company you chose and your delivery address. Finally, here is the result of the manufactured board.