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Week 3: Computer-controlled Cutting

Week 3 Assignment:

  1. Group Assignment

    1. Do my lab’s safety training
    2. Characterize your lasercutter’s focus, power, speed, rate, kerf, joint clearance, and types

  2. Individual Assignment

    1. Cut something on the vinyl cutter
    2. Design, lasercut, and document a parametric construction kit, accounting for the lasercutter kerf
    3. Extra credit:
      • Design it to be assembled in multiple ways
      • Include elements that aren’t flat
      • Engrave as well as cut

GROUP ASSIGNMENT

We gathered together to complete the group assignment. Our instructor demonstrated how to use the laser cutting machine and the vinyl cutter.

Laser Cutting

Chaihuo Makerspace’s laser cutter information:

  • Type: HANS YUEMING LASER CMA1610 (CO2 laser cutting machine)

  • Description: The Han’s Yueming laser cutting machine is a high-precision industrial laser processing device capable of cutting various materials—including metal, acrylic, and wood—quickly, cleanly, and with excellent detail. It is widely used in industrial manufacturing, model making, and advertising fabrication.

  • Focal Length: 50, 63.5mm

  • Laser Power: 80-130W
  • Cutting Speed: 0-36000 (mm/minutes)
  • Engraving Speed: 0-64000 (mm/minutes)
  • Rate (Positioning Accuracy): <0.05mm

  • Cutting Thickness: 0-25mm (depending on material)

  • Voltage: AC220V, 50Hz

  • Work Area: 1600x930mm
  • The environment where the equipment is located should be dry, free from smoke, dust, pollution, vibration, strong electricity, and other intervences

Safety Rules:

  • Open the door to allow proper ventilation and air circulation
  • Turn on the fan/dust removal equipment to remove smoke and toxic gases
  • Turn on the chiller (cooling water method) to cool the machine and prevent overheating
  • Familiarize with the location and operation of the emergency stop button and the fire extinguisher in case of emergency
  • During equipment operation, operators must constantly monitor the equipment’s status. If any abnormality occurs, all power should be immediately cut off, and appropriate measures should be taken
  • Do not stand too close; stay behind the yellow line
  • Do not open the cover while the equipment is in operation
  • After the laser cutting process finishes, wait at least 2 minutes before opening the cover to ensure you do not inhale any smoke or toxic gases
  • All power must be turned off before personnel leave

The Laser Cutting Process

  1. The door must remain open at all times during the process:

  2. Turn on the fan/dust removal equipment:

  3. Turn on the chiller:

  4. Turn on the laser cutting machine:

  5. Turn on the computer:

  6. Open the file on the computer:

  7. (On the computer) Adjust the settings: layer parameters, work parameters, the number of cutting passes, and etc. (different layer colors correspond to different work parameters, allowing you to adjust each shape with different settings):

  8. Set up the laser origin: adjust it using the Up, Down, Left, and Right buttons, then press Origin:

  9. (On the Computer) press Port and then Connect to verify that the USB connection from the computer to the machine is established

  10. (On the Computer) press Go Scale to check the size of the laser cutting area -> the laser head will move around the boundary, allowing you to verify that the cutting area is correct

  11. (On the Computer) press Start to begin the laser cutting process

  12. Stand behind the yellow line all the time while waiting for the cutting process to finish:

  13. After the laser cutting process finishes, wait at least 2 minutes before opening the cover

  14. Take the finish product from the laser cutting machine:

  15. Lastly, remember to turn off all machines and close the door before you leave!

Creating the Design (for Calculating the Kerf)

The OnShape File link

I designed a rectangle with 8 slots, with widths varying from 2.5 mm to 3.2 mm.

Firstly, I set up the variables/parameters (for example, Cut_2 = #Cut_1+0.1mm; Cut_7 = #Cut_6+0.1mm):

Next, I inserted a variable for each of the lengths (when adding a variable, be sure to include # at the beginning):

The gaps between the widths were too small, so I changed the values in the variable table (from 10 mm to 15 mm),

and they updated automatically:

After completing the final design, I exported it as a DXF file (right click on Sketch 1 -> Export as DXF/DWG):

Note

The size was not included in the design. Next time, engraving the original dimensions directly onto the piece would provide a clear reference.

Calculating the Kerf

  1. We measured the actual width with digital caliper (the material is 3mm Basswood):

  2. We wrote the original and actual width on the piece:

  3. From this we can find the kerf size:

    Original (mm) Actual (mm) Difference (mm)
    2.5 2.63 0.13
    2.6 2.8 0.20
    2.7 2.87 0.17
    2.8 3.01 0.21
    2.9 3.19 0.29
    3.0 3.32 0.32
    3.1 3.37 0.27
    3.2 3.43 0.23

    The difference average is = 1.82 / 8 = 0.22mm

    The kerf is 0.11mm (0.22/2 = 0.11mm)

Note

Kerf refers to the width of material removed by the laser during the cutting process.

  1. We printed two identical pieces and tested which joint width produced the strongest press-fit connection. The joint with the original width of 2.7 mm produced the best-fitting connection:

Vinyl Cutter

Chaihuo Makerspace’s vinyl cutter information:

  • Type: Cricut Explorer
  • Description: Precision cutting equipment for paper, vinyl, fabric, and other materials, designed for crafting, decorating, and custom design projects

The Vinyl Cutter Process

The process is quite simple. First, download and install Cricut Design Space. Then, connect your computer to the Cricut machine and upload your images to the software. Place the paper on the Cricut mat, select the appropriate cutting settings, and follow the on-screen instructions to complete the process.

INDIVIDUAL ASSIGNMENT

Parametric Construction Kit

My Mistake

Since we know from the group assignment that the joint with an original width of 2.7 mm produced the best-fitting connection, I created the design based on this, so I didn’t include the Kerf value in the variable/parameter table in OnShape.

The OnShape File link

  1. First, I put the variable/parameter values on the table. Then, I created a circle and put the value = #CircleDiameter:

  2. I drew the joint and put the value for its length = #Length and width = #Width:

  3. I duplicated the joint with Circular Pattern. Then, I also created the chamfer for each joint and put the value = #Chamfer. Chamfers make the joints easier to assemble.

  4. Lastly, I wrote ‘hi’ on one piece so it could be engraved later using the laser cutting machine, and cloned the circle:

This is the laser cutting final result:

Settings

I used the following Work Parameter settings for both the shapes and engraving:

  • Max Factor: 95.00%

  • Min Factor: 75.00%

  • Work Speed: 20.000 mm/s

These settings cut through the 3mm Basswood very well.

Press-fit vs Chamfer Joint

I printed these pieces before, but it didn’t turn out well because I didn’t realize the setting was for double printing instead of a single print. Nevertheless, I was still able to use the pieces to test the difference between a press-fit joint and a chamfer joint.

Press-fit joint:

Chamfer joint:

Conclusion

The press-fit joint is more difficult to assemble and disassemble, but it provide a stronger connection. The chamfer joint is easier to assemble and disassemble, but it may not be as strong as the press-fit joint. The choice between the two depends on the specific requirements of the project, such as whether ease of assembly or strength is more important.

Vinyl Cutter

I cut my 2D design for my final project using Cricut Explorer

I tried to print the game console on paper before, but it failed. I think it was because the design was too small and complex. Or maybe the paper is too thin?