Week03 | Computer Controlled Cutting

Laser Lab Safety

Before operating the EPILOG LASER FUSION cutter at Oulu’s Super FabLab, we participated in a comprehensive lab safety training session conducted by Behnaz. The training covered the following important topics:

1. Awareness of fire hazards and emergency response procedures (e.g., identifying the location of fire extinguishers).
2. The importance of proper ventilation and fume extraction systems.
3. Safe handling of materials to prevent exposure to toxic fumes.
4. Guidelines for machine maintenance and safe operating practices.
5. During the cutting process, always stay alert and keep your eyes on the laser cutter.

Fire Safety

In case of fire, the following steps should be followed when using a fire blanket:

1. Check and read the device tutorial, especially the safety section.
2. Turn off the power or gas source if possible.
3. Pull the tabs to release the blanket.
4. Approach the fire carefully with the blanket as a shield.
5. Cover the burning object completely.
6. Leave the blanket in place until the object cools down.
7. If a person is on fire, wrap them in the blanket, help them lie down, and call for assistance.

This is a fire blanket, designed to stop small fires by smothering them:

General Safety Rules

During the laser cutting and engraving process, the following safety rules should always be applied:

• Ensure that the air input and output systems are open (see the instructions on the wall near the machine).
• Never cut unknown materials.
• Always consult the list of allowed and prohibited materials.
• Never leave the machine unattended during operation.
• After finishing a job, wait at least one minute before opening the lid. This allows toxic gases and smoke to be extracted from the machine before they enter the room.

Proper ventilation and fume extraction are essential because the laser cutter produces smoke and microscopic particles while burning material. Without sufficient airflow, these fumes can accumulate in the workspace, making the air unhealthy to breathe and leaving residue inside the machine. The extraction system removes smoke quickly, keeps the workspace safe, protects users’ lungs, and helps maintain the machine in good condition.

Vent tubes	Vent holes

We should also wait approximately one minute before opening the lid after a laser cut.

Behnaz also reminded us not to press the Emergency Stop button unless an instructor explicitly instructs us to do so. The emergency stop is intended only for serious situations, such as a large fire. Pressing it immediately cuts all power to the machine, including the cooling system, which can potentially damage the laser tube. Therefore, it should only be used when there is no safer alternative.

---

Power and Speed Effects: Raster and Vector

Before measuring cutting parameters, it is important to understand the concept of kerf.

Kerf is the width of the material removed by a cutting process. In simple terms, it is the slit or gap created by a saw, cutting torch, or laser beam. Because the laser beam has a finite width, it removes a small amount of material during cutting.

If kerf is not considered during design, the final parts may not fit together properly. To compensate:

• Internal dimensions should subtract the kerf value.
• External dimensions should add the kerf value.

Basic Preparation Before Laser Cutting

Before starting the cutting process, several preparation steps are required:

1. Set the laser beam origin point on the material to minimize material waste.
2. Perform a focusing test.
3. Place the material sheet on the cutting bed and ensure it is flat and not warped.
4. Turn on the laser system.
5. Prepare the design file and configure it for cutting.

Vector Cutting Test

To evaluate the effect of laser power and head speed, we performed several cutting tests using 3 mm thick MDF. Simple shapes such as rectangles and circles were used.

As a reference, the default settings of the laser cutter in the Oulu Super FabLab are:

• Power: 100
• Speed: 80

For vector testing, we used the following parameters:

• Default speed S12
• Additional speeds tested: S7, S17, S30
• Power levels tested: P80 and P20

The results of the different power and speed combinations are shown below:

Raster (Engraving) Test

The following tests were performed for raster engraving.

Default values for the Epilog 75W laser cutter:

• Power: P100
• Speed: S80

Additional parameters tested:

• Power levels: P70 and P40
• Speed levels: S90, S40, S20

Focus Testing

A focus test is a calibration procedure used to determine the optimal distance between the laser lens and the material surface. At this distance, the laser beam becomes most concentrated, producing the smallest possible spot size and the highest cutting efficiency.

Initially, performing this test can be slightly difficult, but with experience it becomes easier to identify the correct focal position.

We performed the test by cutting a series of small squares while slightly adjusting the Z-axis height of the laser head.

By conducting this test, we observed that proper focus is critical because an unfocused beam spreads out and reduces power density. This results in:

• Wider kerf
• Poor edge quality
• Incomplete cuts
• Increased material waste

Maintaining the correct focus ensures maximum cutting efficiency, precision, repeatability, and overall machine performance.