Class: SolidRuby::Assemblies::PrintedGear

Inherits:
Gear show all
Defined in:
lib/solidruby/assemblies/gear.rb

Overview

Acts the same as Gear, but does produce printable output

Instance Attribute Summary

Attributes inherited from Gear

#height, #hub_dia, #hub_height, #module, #teeth

Attributes inherited from Assembly

#hardware, #skip, #transformations, #x, #y, #z

Attributes inherited from SolidRubyObject

#attributes, #children, #siblings, #transformations

Instance Method Summary collapse

Methods inherited from Gear

#distance_to, #ratio

Methods inherited from Assembly

#*, #+, #-, #add_to_bom, #color, #colorize, #description, get_skip, get_views, #part, #scad_output, #show_hardware, skip, #threads, #transform, view, #walk_tree

Methods inherited from SolidRubyObject

#&, alias_attr, #debug, #debug?, #mirror, #place, #rotate, #rotate_around, #save, #scale, #to_rubyscad, #translate, #union, #walk_tree, #walk_tree_classes

Constructor Details

#initialize(args = {}) ⇒ PrintedGear

Returns a new instance of PrintedGear.



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# File 'lib/solidruby/assemblies/gear.rb', line 71

def initialize(args = {})
  super
  @pressure_angle = args[:pressure_angle] || 20
  @clearance = args[:clearance] || 0.0
  @backlash = args[:backlash] || 0.0
  @twist = args[:twist] || 0.0
  @teeth_to_hide = args[:teeth_to_hide] || 0.0

  @rotation = args[:rotation] || 0.0 # rotation in teeth
end

Instance Method Details

#iang(r1, r2) ⇒ Object 



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# File 'lib/solidruby/assemblies/gear.rb', line 119

def iang(r1, r2)
  Math.sqrt((r2 / r1) * (r2 / r1) - 1) / Math::PI * 180 - degrees(Math.acos(r1 / r2)) # //unwind a string this many degrees to go from radius r1 to radius r2
end

#output ⇒ Object

ported from publicDomainGearV1.1.scad



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# File 'lib/solidruby/assemblies/gear.rb', line 87

def output
  p = @module * @teeth / 2.0
  c = p + @module - @clearance # radius of pitch circle
  b  = p * Math.cos(radians(@pressure_angle)) # radius of base circle
  r  = p - (c - p) - @clearance # radius of root circle
  t  = (@module * Math::PI) / 2.0 - @backlash / 2.0 # tooth thickness at pitch circle
  k  = -iang(b, p) - t / 2.0 / p / Math::PI * 180 # angle to where involute meets base circle on each side of tooth

  points = [
    [0, -@hub_dia / 10.0],
    polar(r, -181 / @teeth.to_f),
    polar(r, r < b ? k : -180 / @teeth.to_f),
    q7(0 / 5, r, b, c, k, 1), q7(1 / 5, r, b, c, k, 1), q7(2 / 5, r, b, c, k, 1), q7(3 / 5, r, b, c, k, 1), q7(4 / 5, r, b, c, k, 1), q7(5 / 5, r, b, c, k, 1),
    q7(5 / 5, r, b, c, k, -1), q7(4 / 5, r, b, c, k, -1), q7(3 / 5, r, b, c, k, -1), q7(2 / 5, r, b, c, k, -1), q7(1 / 5, r, b, c, k, -1), q7(0 / 5, r, b, c, k, -1),
    polar(r, r < b ? -k : 180 / @teeth.to_f),
    polar(r, 181 / @teeth.to_f)
  ]
  paths = [(0..16).to_a]

  res = SolidRubyObject.new
  (0..@teeth - @teeth_to_hide - 1).each do |i|
    res += polygon(points: points, paths: paths).linear_extrude(h: @height, convexity: 10, center: false, twist: @twist).rotate(z: i * 360 / @teeth.to_f)
  end

  res -= cylinder(h: @height + 0.2, d: @bore).translate(z: -0.1)
  res.rotate(z: @rotation * 360.0 / @teeth)
end

#polar(r, theta) ⇒ Object 



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# File 'lib/solidruby/assemblies/gear.rb', line 115

def polar(r, theta)
  [r * Math.sin(radians(theta)), r * Math.cos(radians(theta))] # convert polar to cartesian coordinates
end

#q6(b, s, t, d) ⇒ Object 



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# File 'lib/solidruby/assemblies/gear.rb', line 127

def q6(b, s, t, d)
  polar(d, s * (iang(b, d) + t)) # point at radius d on the involute curve
end

#q7(f, r, b, r2, t, s) ⇒ Object 



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# File 'lib/solidruby/assemblies/gear.rb', line 123

def q7(f, r, b, r2, t, s)
  q6(b, s, t, (1 - f) * [b, r].max + f * r2) # radius a fraction f up the curved side of the tooth
end

#show ⇒ Object 



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# File 'lib/solidruby/assemblies/gear.rb', line 82

def show
  output
end