3. Computer-controlled cutting

Overview of week 3 assignment

1. Group assignment
   1. do your lab's safety training
   2. characterize your lasercutter’s focus, power, speed, rate, kerf, joint clearance and types
2. Individual assignment
   1. design, lasercut, and document a parametric construction kit, accounting for the lasercutter kerf, which can be assembled in multiple ways, and for extra credit include elements that aren’t flat
   2. cut something on the vinylcutter

1. Group assignment

For more information, see the Week 03: Group assignment page.

A. Safety training

1. Never leave the lasercutter during cutting
2. Flammable materials can ignite
3. Ensure the fire extinguisher is accessible
4. Verify Dust collection exhaust and Compressor are functioning
5. Do not process materials that produce toxic or corrosive gases (e.g., PVC)
6. Avoid direct exposure to the strong light

Check the laser settings before starting cutting!

UCP (lasercutter app) erases previous settings when importing a new file and reverts to default settings for acrylic, which can deliver too much power to different materials (such as cardboard) and cause a fire. By opening setting tab before importing data, previous cutter settings are preserved.

B. Characterization of the lasercutter

Lasercutter in FabLab Kannai: VLS Desktop VLS2.30
Manual: VLS Desktop User Guide Rev 2012-08.pdf

• Laser Material Processing Area (W x H): (406 x 305 mm)
• Laser oscillator: 30W, CO2 laser

There are 3 key parameters for press-fit lasercutting; Thickness, Kerf and Clearlance.

1. Cardboard thickness: 5.18mm
2. Kerf: 0.18mm
3. Clearlance: -0.1mm

2. Individual assignment

A. Parametric construction kit

While designing a parametric construction kit, initially, I found the concept of kerf for press-fit a bit confusing and wasn’t sure how to adjust the parameters. Below is a visual explanation of the concept.
Concept of Kerf for press-fit

Inspired by Flexture mechanism, I tried making something flexible out of cardboard. Below are parametric difinition on Fusion 360 using 3 lasercutting parameters.
3 parameters set in Fusion 360

Following are steps to use lasercutter after designing.

1. Export SVG using Shaper Utilities, move files to the laptop connected to the lasercutter, using USB drive
2. Import files with CorelDRAW, set colors to control lasercutter
   (Left click to set fill, right click to set line color)
   • Black fill for engraving
   • Red lines for cutting (Check lines are set to "Hairline" on the bottom tight corner)
3. Send data to UCP (Universal Control Panel) by Ctrl + P (To reuse previous UCP settings, open UCP setting tab first)
4. Prepare the lasercutter
   1. Set focus using "focus tool"
   2. Arrange data and check material has enough dimensions
   3. Setting
      • Material database
      • Manual control
   4. Check the safety procedure again

My first attempt was too wide and not very flexible, so I adjusted it a few times until it had some flexibility. However, I originally wanted it to be flexible with rotation, but it didn’t work out that way probably because of the nature of cardboard.
This kit can be constructed in different ways, including:

• Building flexible tower
• Flexible hanging object
• And TIE fighter

B. Vinylcutter

In FabLab Kannai, we used Silhouette Curio 2 vinylcutter. I tried cutting ISO symbol (ISO7010 - W004) and used it to sandblast my plastic bottle, follwing steps below.

1. Install Silhouette Studio, setup machine name
2. Import DXF data
3. Place a material on the electrostatic mat
   (not enough force, so I added masking tape to fix)
4. Set and lock the tool
5. Detect material thickness (button on the top right)
6. Set parameters
   Parameter to cut only adhesive sheet and left base film (or release paper)
   (In our case, Blade depth: 2, Force: 14, Speed: 8)
7. Test (test the parameters by cutting small piece at the corner)
8. Send and cut!

C. Sansblast

Using the adhesive sheet cut into the shape of the symbol, we tried sandblasting on a bottle following the steps below.

1. Attach “application film” on the top
   (Application film is used to place all the pieces of the symbol together as one piece)
2. Peel off the application film with the symbol from release paper
3. Attach the symbol on the bottle and mask the rest of the bottle
4. Turn on the compressor
5. Sandblast in the box (be careful not to scatter sand)
6. Remove the masking and clean... done

Don't stare at the laser, drink water! (but don't leave)

3. Design files

• Press-fit construction kit (F3D)
• Press-fit construction kit (SVG)
• Vinylcutter - ISO NOT compliant symbols (SVG)

Afterthought

• I was satisfied with the precision of lasercutter and the burnt smell but regretted my rushed design. After cutting, I saw improvements: adding press fits on all sides and diagonal slots for cross-shaped assembly.
• Cutting and sandblasting are FUN.
• Sandblasting the plastic bottle was pretty successful, but left some small scratches from the residual sand. Also, the extremely sharp corners of the symbol should have been rounded.