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3. Computer Controlled Cutting

This week, I learned many things related to laser cutting, including how the machine works and how to determine the optimal speed and power settings for both cutting and engraving. I also learned about kerf—what it is and how to measure it. Additionally, I implemented a simple press-fit design using different types of joints: fillet, chamfer, and a standard joint. The fillet joint provided the best fit, as it was easy to insert into the comb. Moreover, I gained deeper insights into parametric design and how to create it using CAD software.

Laser Cutting

1. Group Assignment

Our lab instructor introduced us to the safety instructions and demonstrated how to use the Trotec Speedy 400 laser cutter along with its accompanying software.

Safety Instructions

Before operating the laser cutter, we were instructed on essential safety measures, including:

  • Wearing protective eyewear to prevent exposure to laser reflections.
  • Ensuring proper ventilation to remove fumes produced during cutting.
  • Regularly cleaning the lens and mirrors to maintain cutting precision.
  • Avoiding the use of highly flammable or hazardous materials in the laser cutter.

1.1 Testing MDF (4mm)

Cutting and Engraving

My teammate and I selected a template to test the laser cutter’s performance on a 4mm MDF plate for both cutting and engraving.

To determine the best power and speed settings:

  1. We first fixed the speed at 1 and varied the power from 20% to 95%.
  2. After comparing the results, we identified the best cut—the one that was almost completely cut through but not overburnt.
  3. We then fixed this optimal power value and adjusted the speed to refine the settings further.

the pest power and speed for cutting the MDF 4mm was 55% and 0.27 respectively.

We followed a similar procedure for engraving by adjusting the power while keeping other parameters constant.

That was bad because the speed was slow, so we made it faster and got a good result!

the pest power and speed for engraving the MDF 4mm was 40-80% and 50 respectively.

Kerf Measurement

To measure the kerf (the material lost due to laser cutting), my teammate designed 12 squares and arranged them in a row. After cutting, we measured the total gap left behind and divided it by the number of cuts, then divided the result by two (since kerf affects both sides of a cut).

Kerf = 0.4/13 = 0.03/2 = 0.015mm

This provided us with the kerf value for 4mm MDF.

1.2 Testing White Acrylic (3mm)

Cutting white acrylic posed a challenge due to its reflective properties, which made it difficult for the laser to penetrate.

  1. We initially followed the same process as with MDF, fixing the speed at 1 and varying the power from 20% to 95%. However, the laser failed to cut through as the speed was too high.
  2. We adjusted the power to 40%, which resulted in an improved but still incomplete cut.
  3. By reducing the speed and fine-tuning it between 0.125 and 0.35, we finally achieved a clean cut at 40% power, 0.25 speed, and 1000 Hz frequency.

This testing helped us determine the best settings for cutting 3mm acrylic effectively.

1.3 Testing Press-Fit Joints

To test press-fit tolerances for 4mm MDF and 3mm acrylic, we designed a comb with 11 slots ranging from 4.25mm to 3.75mm for the MDF 4mm, with increments of 0.05mm between each slot. Additionally, we created a 4mm hole in a square piece to test how well the material would fit into the slots.

For the comb design, I used parametric equations, ensuring that each hole size was mathematically linked to the next with an increment or decrement of 0.05mm. This approach allowed for easy adjustments and precise fits in future designs.

By testing different combinations, we found that the best fit was at 3.95mm. This was the most secure press fit without requiring excessive force.

2. Press-Fit Kit Design

I designed multiple press-fit components using SolidWorks, focusing on simple yet engaging shapes suitable for children.

These components can be assembled into various structures, such as:

Car

Giraffe

Table and Multi-Layered Table

Space Orbit Model

Drone

These designs demonstrate how parametric modeling and laser cutting can be combined to create customizable, interactive kits for education and prototyping.

I used the Roland GS-24 machine to make a laptop sticker. I explored how it cuts materials; it is a very simple machine. I decided to cut the Fab Academy logo to put on my laptop, so I opened the logo in Inkscape. Then, I printed it and ensured that the dimensions of the printed object matched the design.

Challenges and Troubleshooting

During laser cutting, we encountered an issue where the nozzle and lens were misaligned, causing the machine to fail in cutting objects properly.

Steps Taken to Fix the Issue:

  1. We carefully realigned the nozzle and lens to ensure the laser beam was correctly focused.
  2. We checked and cleaned all mirrors to remove dust and residue that might affect the laser’s intensity.
  3. After these adjustments, the machine performed as expected, producing clean and precise cuts.

This troubleshooting experience highlighted the importance of regular maintenance in ensuring the laser cutter operates efficiently.

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