W04 Computer-Controlled Cutting

Laser Cutting
Laser cutting is a technology that uses a laser to cut materials, and is typically used for industrial manufacturing applications, but is also starting to be used by schools, small businesses, and hobbyists. Laser cutting works by directing the output of a high-power laser most commonly through optics. The laser optics and CNC (computer numerical control) are used to direct the material or the laser beam generated. A commercial laser for cutting materials involved a motion control system to follow a CNC or G-code of the pattern to be cut onto the material. The focused laser beam is directed at the material, which then either melts, burns, vaporizes away, or is blown away by a jet of gas,leaving an edge with a high-quality surface finish. Industrial laser cutters are used to cut flat-sheet material as well as structural and piping materials.

During my college days, one structure that always fascinated me was Buckmister Fuller’s Geodesic domes. So I decided to choose this for the press fit kit project.

To begin with, I started by learning more about the geometry involved in the design.

A geodesic polyhedron is a convex polyhedron made from triangles. They usually have icosahedral symmetry, such that they have 6 triangles at a vertex, except 12 vertices which have 5 triangles. They are the dual of corresponding Goldberg polyhedra with mostly hexagonal faces.

Geodesic polyhedra are a good approximation to a sphere for many purposes, and appear in many different contexts. The most well-known may be the geodesic domes designed by Buckminster Fuller, which geodesic polyhedra are named after.

An elliptical geodesic polyhedra

Instead of a spherical form I decided to go with an elliptical geodesic polyhedra.

It will have 12 pentagonal faces and 20 hexagonal faces. An Augment or kis operation is done to create triangle faces. I opted for the 3 frequency subdivision.

This will result in 60 triangles that form 12 pentagons and 120 triangles that form 20 hexagons,

The dimension of the Legs that forms the pentagon are 69.72mm, 69.72mm and 80.7mm at an angle of 55, 55, 71.

The dimension of the Legs that forms the hexagon are 82.49mm, 82.49mm and 80.7mm at an angle of 61, 61, 59.

Parametric design

The below image shows all the components involved in the parametric design.

Parametric constraints

The parametric constraints that I pre-defined are,

- Thickness: 3.85mm

- Kerf: 0.15mm

- Depth: 2.25*Thickness

- Cut: Thickness - (2*Kerf)

- Arm: Thickness + (2*Kerf) + 1.5

Preparing the file for Laser machine

The entire cut work was composed in 5 sheet of size 300mm x 600mm.