Triangle

FreeCAD to KiCAD PCB outline export

* Select face that you want as PCB outline
* Make sure face is aligned with the view
* With KiCAD StepUp plugin: project selected face to 2D
* Convert 2D object to sketch
* Export sketch to PCB layer

* [Arranging PCB components in a circle with a script](http://kevincuzner.com/2017/04/28/arranging-components-in-a-circle-with-kicad/)

• Postprocessing

  • Chamfer alignment stickouts at the bottom (0.8mm)
  • Chamfer bottom of the triangle (1mm)
  • Fillet the 3 corners of the triangle (1mm)

LED Sphere

• Isosahedron: 20 triangular faces

  Progression: 1, 1+3 = 4, 4 + 5 = 9, 9 + 7 = 16, 16 + 9 = 25, 25 + 11 = 36, 36 + 13 = 49

  • 1 triangle -> 1 triangle: 20 faces
  • 1 triangle -> 4 triangles: 80 faces
  • 1 triangle -> 9 triangles: 180 faces
  • 1 triangle -> 16 triangles: 320 faces
  • 1 triangle -> 25 triangles: 500 faces

Possibilities:

* 80 faces, but divide each face into 16 LEDs -> 1280 LEDs
* 80 faces, but divide each face into 25 LEDs -> 2000 LEDs
* 80 faces, but divide each face into 36 LEDs -> 2880 LEDs
* 80 faces, but divide each face into 49 LEDs -> 3920 LEDs

• 20 faces printed.

  • 2-sided triangle: 3 LEDs -> 60 LEDs
  • 3-sided triangle: 6 LEDs -> 120 LEDs
  • 4-sided triangle: 10 LEDs -> 200 LEDs
  • 5-sided triangle: 15 LEDs -> 300
  • 6-sided triangle: 21 LEDs -> 420
  • 7-sided triangle: 27 LEDs -> 540
  • 8-sided triangle: 35 LEDs -> 700

Plug-in LEDs

• WS2812D-F8: $0.11 for 100+

  • inner diameter: 8.0mm, outer diameter: 9.2mm
  • datasheet
  • LCSC
  • 3.5V -> 5.3V
  • Needs capacitor and 75 Ohm resistor between VDD/GND per LED

• 75Ohm resistor

• 100nF cap

References

• Geodesic(k) LED Spheres

  • Build instructions

• Construct an icosahedron

• Construct an icosahedron in FreeCAD

• Construction of regular icosahedron within a given sphere

  "From this it is manifest that the square on the diameter of the sphere is five times the square on the radius of the circle from which the icosahedron has been described, and that the diameter of the sphere is composed of the side of the pentagon and two of the sides of the decagon inscribed in the same circle."

  Dsphere^2 = 5 * (Rpent^2)

  Rpent = sqrt(Dsphere^2/5) = Dsphere/sqrt(5) = 2 * Rsphere / sqrt(5)

• Ad Quadratum Construction and Study of the Regular Polyhedra

• Freecad scripting tutorial

• Freecad Topological data scripting

FreeCAD comments

• Base.Vector getAngle -> radians, all other functions -> degrees

• Simply viewing actions, such as aligning view to face are not present out of the box

• aligning a object along an axis is broken.

• Location of buttons in the toolbar always changes

• Add spheres for orientation

• FreeCAD over OpenSCAD: interactivity

• The number of LEDs must be chosen so that there's room in the center for a screw.

• When doing an align operation on a object that was created by an assembly of multiple identical components, first create a Compound of it in Part. Otherwise, the align seems to happen on the main component, not on the additional copies.