Caterpillar Chain Wheel

chainwheel.py

#!/usr/bin/python
#
# Caterpillar Chain Wheel
# derived from OpenSCAD script from http://www.thingiverse.com/thing:8877
#

import sys
from math import *
from cadmium import *

width=7
edge=6
radio=93.5/2
drill = 3.5

disc = Cylinder(radius=radio, height=width)

holes = []
for i in range(edge):
  holes.append(
    Cylinder(radius=radio, height=width*2)
      .translate(0, radio*2-radio/4.5, 0)
      .rotate(Z_axis, i*360/edge)
  )
  holes.append(
    Cylinder(radius=radio/3, height=width*2)
      .translate(radio/5.5, radio*1.075, 0)
      .rotate(Z_axis, i*360/edge)
  )
  holes.append(
    Cylinder(radius=radio/3, height=width*2)
      .translate(-radio/5.5, radio*1.075, 0)
      .rotate(Z_axis, i*360/edge)
  )
for i in range(4):
  holes.append(
    Cylinder(radius=drill/2, height=2*width, center=True)
      .translate(
        0.75*(radio-5)*cos(2*pi/4*i),
        0.75*(radio-5)*sin(2*pi/4*i),
        0)
    )

star_wheel = disc - reduce(lambda x,y: x+y, holes)

center_holes = Cylinder(radius=21.5/2, height=20).translate(0,0,10) + \
    Cylinder(radius=4.2, height=30, center=True)
center_holes.translate(0,0,3)

chainwheel = star_wheel - center_holes

chainwheel.toSTL('chainwheel.stl')