4. Computer controlled cutting

Group assignment requirments

This week, our group explores our laser cutting machines’ essential features, like focus, power, speed, and kerf. We aim to understand these aspects thoroughly and document our findings.

The group assignment for this week is the following:
- Characterize your lasercutter’s focus, power, speed, rate, kerf, joint clearance and types.
- Document your work on the group work page and reflect on your individual page what you learned about characteristics of your printer

Laser cutting machine specs

• Machine name: Trotec Speedy 400
• Machine max power in Watts: 120W
• Machine bed size (work area): 1016mm x 610mm
• Machine type: CO2
• Toolpath generation software used: Trotec JobControl

Safety

Safety measures include: - Fire extinguisher located within reach - Clear signage indicating safe distances - Safety goggles must be worn at all times during operation

Focus

The focus position of the laser cutting machine is the relative position between the focus and the upper surface of the workpiece, based on the machined material surface.

First, we created multiple horizontal lines in Inkscape and then colored them according to the 16 different colors recognized by the Trotec laser software.

Next, using the Trotec software, we adjusted the z-offset for each color by 1mm increments. The z-offset was changed using the metal focus tool distance as the reference point. We started from the initial focus point and gradually incremented the z-offset, going up to +10mm and down to -5mm.

During this process, we observed the laser beam’s behavior and noted the point at which it achieved the smallest size possible, indicating the optimal focus distance. Through meticulous testing and adjustment, we determined that the best focus distance for our laser cutter was found to be 25mm. This ensured optimal performance and precision during laser cutting and engraving processes.

Power and speed

We began by creating a 4x4 grid of squares in Inkscape, with each square outlined in a different color from the 16 available colors recognized by the Trotec laser cutter. Each color represented a unique set of power and speed settings.

We meticulously adjusted the settings for each color to have varying power and speed combinations. To systematically explore the capabilities of the laser cutter, we altered the power settings of the rows in increments of 10%, ranging from 100% to 70%. Additionally, we adjusted the speed settings in increments of 0.2, ranging from 0.1m/s to 0.7m/s.

Then we repeated the test for another set of power values, also adjusting by increments of 10%, starting from 60% to 30%.

The material used for the test was MDF, with a thickness of 3.3mm. This specific material and thickness were chosen due to it being commonly used in real-world cutting applications.

After executing the test cuts, we manually recorded the speed and power settings used for each square before inspecting the results. Through careful observation and analysis, we identified the optimal combination of power and speed settings for our laser cutter when working with MDF material of 3.3mm thickness.

-100% power, 0.3 speed.

Rate

The rate at which the laser pulses or fires. For this material, we used a rate of 1000 Hz.

Kerf & joint clearance

Cutting kerf is the amount of material that is removed by the cutting process. This information is crucial when designing joints since the design used must account for the cutting kerf to be able to fit properly.

We utilized the kerf test generator available at this link. This tool allowed us to generate a file containing comb-like structures with various slot thicknesses, simulating different kerf sizes. The file was customized to suit our material thickness and testing requirements.

After generating the file, we proceeded to cut two comb structures using our laser cutter. Each comb had multiple slots with varying thicknesses. We carefully observed and tested each slot to determine the best fit with our chosen speed and power settings.

Through testing, we found that the slots with a thickness of 3.1mm provided the best fit for both combs. This observation allowed us to calculate the cutting kerf, which was determined to be 0.1mm (calculated as half of the difference between the material thickness and the best fit slot thickness).

By understanding the cutting kerf and optimizing our laser cutter settings accordingly, we ensure precise and accurate cuts, vital for achieving high-quality results in our laser cutting projects.

Sources

The information referenced in this page was found in the following sources:
Source 1
Source 2
Source 3