Parametric construction kit
Laser cut parts that account for kerf and assemble in multiple ways.
What I did in Week 03
The work this week focused on understanding and using computer controlled cutting tools, especially the laser cutter and vinyl cutter, and documenting a parametric construction kit that can be assembled in multiple ways.
- Lab safety & characterization: trained on the laser cutter and characterized focus, power, speed, rate, kerf, joint clearance, and joint types.
- Parametric construction kit: designed and cut parts that account for laser kerf and allow multiple assemblies, including non-flat elements.
- Vinyl cutting: prepared and cut designs on the vinyl cutter using appropriate materials.
- Documentation: organized notes on tools, CAD workflow, joints, and laser parameters for future reference.
Assignments for the week:
- Do your lab's safety training and characterize your laser cutter's focus, power, speed, rate, kerf, joint clearance, and joint types.
- Cut something on the vinyl cutter.
- Design, laser cut, and document a parametric construction kit that can be assembled in multiple ways and accounts for laser kerf.
- For extra credit, include elements that are not flat.
Week 03 assignments and links
Here are the individual and group assignment pages for this week.
Computer controlled cutting tools
Computer controlled cutting covers a range of tools with different materials and applications.
Tools overview
- Knife cutters: including ultrasonic knives for precise cutting of thin and flexible materials.
- Laser cutters: use focused light energy, similar to a microwave source, to cut or engrave materials.
- Plasma cutters: create a plasma arc that melts through conductive materials, similar to welding.
- Water jet cutters: use a supersonic jet of water with garnet abrasive to cut glass, stone, or thick steel.
- Hot wire cutters: use heated wire to melt and shape foam, often for architectural trims.
- Wire EDM: enables very high resolution, high aspect ratio cutting in metals for machine components.
CAD and workflow notes
- Use Inkscape extensions to prepare files for laser cutting.
- The design is sent to the machine through a printer driver; different machines use different drivers.
- Mods is an open program that supports PNG and SVG input and can output directly to various cutters.
- More advanced cutters can control the cutting angle and tilt to improve edge quality.
Vinyl cutter materials
- Epoxy film electrical tape, which tolerates high temperature and can be used for soldering masks.
- Copper tape for cutting simple circuits and conductive patterns.
- Example project: Honghao Deng's work cutting circuits with knives.
Laser cutting fundamentals
Laser cutting depends on understanding kerf, material behavior, and how machine settings interact.
Joints and parametric design
A parametric model lets one parameter change propagate through the whole design, which is critical for adjusting kerf and material thickness.
Axial joints
- Chamfer: slightly misaligned edges that help compress the material for a tighter fit.
- Snap fit: a bump engages into a slot so parts snap together and stay in place.
- Flexure: a thin beam that bends or buckles to provide compliant motion or holding force.
- Pinned: a pin passes through parts to fix or allow controlled rotation.
Right-angle joints
- Finger joints: interlocking "fingers" that hold plates together but may not resist all loads.
- Snap joints: right-angle joints with features that snap into place.
- Wedge joints: wedges fit into tight tolerances to lock parts together.
Kerf and material behavior
Kerf is the material removed by a tool when it passes through a workpiece, and it must be considered in slot widths and joint clearances.
Flat sheets can be cut with patterns that allow them to bend, and repeated beams can create controlled parallel motion.
Laser types
- CO₂ laser: the most common laser cutter source, operating around 10.6 µm.
- Fiber laser: an optical fiber doped with metal, typically operating around 1–2 µm.
Settings and modes
- Focus: the distance from the lens to the material surface where the beam is smallest.
- Power: determines how much energy is delivered to cut through the material without burning it.
- Speed: how fast the head moves; it needs to be balanced with power to cut cleanly.
- Rate: controls how quickly pulses or passes are applied.
- Passes: number of times the laser goes over the same path to complete the cut.
- Vector mode: follows lines and curves to cut or score.
- Raster mode: scans back and forth to engrave filled areas like an image.
Safety notes:
- Safety around laser cutters is essential; always follow lab training and procedures.
- Cardboard works well on vinyl cutters and has a smooth cut and renewable source.
- Certain foods such as pasta can be cut when wet, but only in appropriate, food-safe setups.
Evidence (images)
Replace these placeholder images in images/week3/ with your own screenshots and photos from this week.
Vinyl cutter design
Prepared and cut designs with suitable materials like epoxy film and copper tape.
Laser characterization
Tests for focus, power, speed, rate, and kerf to find reliable settings.
Joint experiments
Axial and right-angle joint tests for the construction kit.
Next step
After characterizing the laser cutter and building a parametric construction kit, the next weeks will apply these skills to more complex assemblies and integration with other digital fabrication processes.