opel-cad/opel_pin.py

from build123d import *
from ocp_vscode import show

# ==========================================
# --- MASTER PARAMETERS ---
model_size = 31.0  # Outer diameter of the ring
overhang = model_size * (3.0 / model_size)     # How many mm the bolt sticks out past the ring
# ==========================================

# --- Derived Parameters ---
outer_diameter = model_size
inner_diameter = model_size * (25.4 / model_size)
thickness      = model_size * (2.3 / model_size)

pin_diameter   = model_size * (3.1 / model_size)
pin_length     = model_size * (10.8 / model_size)
pin_spacing    = model_size * (14.0 / model_size)
pin_height_offset = model_size * (1.55 / model_size)
fillet_radius  = model_size * (0.15 / model_size)

# --- Lightning Bolt Proportions ---
W = (outer_diameter / 2) + overhang
bound = model_size 
H_outer = model_size * (3.1 / model_size) 
H_inner = model_size * (0.5 / model_size)
X_point = model_size * (5.8 / model_size)
X_inner = model_size * (2.7 / model_size)

with BuildPart() as opel_pin:
    # 1. Base Ring
    with BuildSketch() as ring_sketch:
        Circle(outer_diameter / 2)
        Circle(inner_diameter / 2, mode=Mode.SUBTRACT)
    extrude(amount=thickness)

    # 2. Lightning Bolt Profile (Aggressive Z-Shape)
    with BuildSketch() as bolt_sketch:
        pts = [
            (-bound, H_outer),           # 1. Top-left outer edge
            (-bound, -H_inner),          # 2. Bottom-left outer edge of upper bar
            (-X_inner, -H_inner),        # 3. Inner bottom corner (cuts right, past center)
            (-X_point, -H_outer),        # 4. Sharp bottom-left point (diagonals back left)
            (bound, -H_outer),           # 5. Bottom-right outer edge
            (bound, H_inner),            # 6. Top-right outer edge of lower bar
            (X_inner, H_inner),          # 7. Inner top corner (cuts left, past center)
            (X_point, H_outer)           # 8. Sharp top-right point (diagonals back right)
        ]
        z_shape = Polygon(*pts)

        # Fillet the 2D corners of the Z shape so the inner zig-zag isn't infinitely sharp
        fillet(z_shape.vertices(), radius=fillet_radius)
        
        # Cleanly slice off the overhangs
        Circle(W, mode=Mode.INTERSECT)
    extrude(amount=thickness)

    # ==========================================
    # ---> THE FIX: Fillet ALL top edges <---
    # 1. Grab the highest face on the Z-axis (the newly merged face of both ring + bolt)
    top_face = opel_pin.faces().sort_by(Axis.Z)[-1]
    
    # 2. Grab ALL edges of that top face (no filtering)
    all_top_edges = top_face.edges()
    
    # 3. Apply the 3D fillet to the entire border
    fillet(all_top_edges, radius=fillet_radius)
    # ==========================================

    # 3. Mounting Pins (on the back face)
    bottom_face = opel_pin.faces().sort_by(Axis.Z)[0]
    
    with BuildSketch(bottom_face) as pin_sketch:
        with Locations((-pin_spacing, -pin_height_offset), (pin_spacing, pin_height_offset)):
            Circle(pin_diameter / 2)
            
    extrude(amount=pin_length)

# --- Export for 3D Printing ---
# This saves a STEP file in the same folder as your python script
export_step(opel_pin.part, "vintage_opel_pin.step")

# --- Send to OCP CAD Viewer ---
show(opel_pin)