Class: CrystalScad::Gears::PrintedGear

Inherits:
Gear show all
Defined in:
lib/crystalscad/Gears.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

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

Attributes inherited from Primitive

#children

Attributes inherited from CrystalScadObject

#args, #transformations

Instance Method Summary collapse

Methods inherited from Gear

#distance_to, #ratio

Methods inherited from Assembly

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

Methods inherited from Primitive

#mirror, #rotate, #rotate_around, #scale, #transform, #translate, #union

Methods inherited from CrystalScadObject

#save, #to_rubyscad, #walk_tree, #walk_tree_classes

Constructor Details

#initialize(args = {}) ⇒ PrintedGear

Returns a new instance of PrintedGear.



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# File 'lib/crystalscad/Gears.rb', line 74

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

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class CrystalScad::Assembly

Instance Method Details

#degrees(a) ⇒ Object 



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# File 'lib/crystalscad/Gears.rb', line 122

def degrees(a)
  a*180 /  Math::PI
end

#iang(r1, r2) ⇒ Object 



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# File 'lib/crystalscad/Gears.rb', line 130

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/crystalscad/Gears.rb', line 90

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 = CrystalScadObject.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/crystalscad/Gears.rb', line 126

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/crystalscad/Gears.rb', line 138

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/crystalscad/Gears.rb', line 134

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

#radians(a) ⇒ Object 



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# File 'lib/crystalscad/Gears.rb', line 118

def radians(a)
  a/180.0 * Math::PI
end

#show ⇒ Object 



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# File 'lib/crystalscad/Gears.rb', line 85

def show
  output
end