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• Testing Macro Drawings

  GOAT INDUSTRIES • 3 hours ago • 0 comments

  First Macro drawing for FreeCad is just to check it can be done easily. It works. Here is the first Macro:

  import FreeCAD as App
  import Part
  import math
  try:
      from PySide import QtCore
  except ImportError:
      from PySide6 import QtCore
  
  doc_name = "Chain_Sprocket_13T_15T_Simulation"
  doc = App.newDocument(doc_name)
  
  # --- 1. System Parameters ---
  t1 = 13 # Left Sprocket Teeth
  t2 = 15 # Right Sprocket Teeth
  pitch = 9.525
  roller_diameter = 6.35
  bore_diameter = 10.0
  plate_thickness = 5.3
  num_links = 32 # Increased chain length to accommodate larger sprocket
  
  # Chain Link Specs
  inner_width = 5.72
  pin_diameter = 3.28
  link_plate_thickness = 1.3
  
  # Calculated Radii
  R1 = pitch / (2 * math.sin(math.pi / t1))
  R2 = pitch / (2 * math.sin(math.pi / t2))
  root1 = R1 - (roller_diameter / 2.0)
  root2 = R2 - (roller_diameter / 2.0)
  
  # --- 2. Iterative Solver for Exact Center Distance (C) ---
  # A closed chain requires a geometrically perfect loop length.
  L_target = num_links * pitch
  C = 85.0 # Initial guess
  for _ in range(50): # Newton-Raphson method for exact distance
      theta = math.asin((R2 - R1) / C)
      L_calc = 2 * C * math.cos(theta) + R1 * (math.pi - 2*theta) + R2 * (math.pi + 2*theta)
      C -= (L_calc - L_target) / (2 * math.cos(theta))
  
  # Final Path Geometry Variables
  theta = math.asin((R2 - R1) / C)
  L_str = C * math.cos(theta)
  L_arc1 = R1 * (math.pi - 2 * theta)
  L_arc2 = R2 * (math.pi + 2 * theta)
  L_total = L_arc1 + L_arc2 + 2 * L_str
  
  # Tangent Points defining the path layout
  T1top = App.Vector(-R1 * math.sin(theta), R1 * math.cos(theta), 0)
  T1bot = App.Vector(-R1 * math.sin(theta), -R1 * math.cos(theta), 0)
  T2top = App.Vector(C - R2 * math.sin(theta), R2 * math.cos(theta), 0)
  T2bot = App.Vector(C - R2 * math.sin(theta), -R2 * math.cos(theta), 0)
  
  # --- 3. Dynamic Sprocket Generator ---
  def create_sprocket(name, teeth, R_pitch, R_root):
      R_outer = R_pitch + 2.3 # Scaled OD
      base_cylinder = Part.makeCylinder(R_outer, plate_thickness)
      scale_y = 0.85 
      
      # Parameterized Wedge Cutter to adapt to different radii
      p_root = App.Vector(R_root, 0, 0)
      p_A = App.Vector(R_pitch - 1.6, 2.77 * scale_y, 0)
      p_B = App.Vector(R_pitch - 1.6, -2.77 * scale_y, 0)
      p_M_up = App.Vector(R_pitch + 1.75, 4.5 * scale_y, 0)
      p_M_low = App.Vector(R_pitch + 1.75, -4.5 * scale_y, 0)
      p_3 = App.Vector(R_pitch + 5.1, 5.5 * scale_y, 0)
      p_4 = App.Vector(R_pitch + 5.1, -5.5 * scale_y, 0)
  
      arc_root = Part.Arc(p_B, p_root, p_A).toShape()
      arc_up = Part.Arc(p_A, p_M_up, p_3).toShape()
      arc_low = Part.Arc(p_4, p_M_low, p_B).toShape()
      line_out = Part.LineSegment(p_3, p_4).toShape()
  
      wedge_wire = Part.Wire([arc_root, arc_up, line_out, arc_low])
      wedge_solid = Part.Face(wedge_wire).extrude(App.Vector(0, 0, plate_thickness + 2.0))
      wedge_solid.translate(App.Vector(0, 0, -1.0))
  
      sprocket = base_cylinder
      for i in range(teeth):
          cutter = wedge_solid.copy()
          cutter.rotate(App.Vector(0, 0, 0), App.Vector(0, 0, 1), i * (360.0 / teeth))
          sprocket = sprocket.cut(cutter)
          
      bore = Part.makeCylinder(bore_diameter / 2.0, plate_thickness + 2.0)
      bore.translate(App.Vector(0, 0, -1.0))
      
      obj = doc.addObject("Part::Feature", name)
      obj.Shape = sprocket.cut(bore)
      obj.ViewObject.ShapeColor = (0.2, 0.2, 0.2)
      return obj
  
  sprocket_1 = create_sprocket("Sprocket_13T", t1, R1, root1)
  sprocket_2 = create_sprocket("Sprocket_15T", t2, R2, root2)
  sprocket_2.Placement.Base = App.Vector(C, 0, 0)
  
  # --- 4. Chain Link Geometry ---
  def create_link_plate(thickness, z_offset):
      r = 4.0
      cyl1 = Part.makeCylinder(r, thickness, App.Vector(0,0,z_offset))
      cyl2 = Part.makeCylinder(r, thickness, App.Vector(pitch,0,z_offset))
      box = Part.makeBox(pitch, r*2, thickness, App.Vector(0, -r, z_offset))
      return cyl1.fuse(cyl2).fuse(box)
  
  inner_plate_z1 = plate_thickness/2 + inner_width/2
  inner_plate_z2 = plate_thickness/2 - inner_width/2 - link_plate_thickness
  p1 = create_link_plate(link_plate_thickness, inner_plate_z1)
  p2 = create_link_plate(link_plate_thickness, inner_plate_z2)
  r1 = Part.makeCylinder(roller_diameter/2, inner_width,...

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