Slot-based connectors for crown side guards

nhf/touhou/shiki_eiki/crown.py

@@ -3,6 +3,7 @@ from nhf.build import Model, target, assembly, TargetKind
 import nhf.utils
 
 import math
+from typing import Optional
 from dataclasses import dataclass, field
 from enum import Enum
 import cadquery as Cq
@@ -11,6 +12,8 @@ class AttachPoint(Enum):
     DOVETAIL_IN = 1
     DOVETAIL_OUT = 2
     NONE = 3
+    # Inset slot for front surface attachment       j
+    SLOT = 4
 
 @dataclass
 class Crown(Model):
@@ -20,9 +23,15 @@ class Crown(Model):
     base_circ: float = 538.0
     # Upper circumference, at the middle
     tilt_circ: float = 640.0
+    front_base_circ: float = (640.0 + 538.0) / 2
     # Total height
     height: float = 120.0
 
+    # Front guard has a wing that inserts into the side guards.
+    front_wing_angle: float = 9.0
+    front_wing_dh: float = 40.0
+    front_wing_height: float = 20.0
+
     margin: float = 10.0
 
     thickness: float = 0.4 # 26 Gauge
@@ -33,6 +42,13 @@ class Crown(Model):
     side_guard_hole_diam: float = 1.5
     side_guard_dovetail_height: float = 30.0
 
+    side_guard_slot_width: float = 22.0
+    side_guard_slot_angle: float = 18.0
+    # brass insert thickness
+    slot_thickness: float = 2.0
+    slot_width: float = 20.0
+    slot_tilt: float = 45
+
     material: Material = Material.METAL_BRASS
     material_side: Material = Material.PLASTIC_PLA
 
@@ -43,6 +59,9 @@ class Crown(Model):
         assert self.facet_width_upper / 2 > self.height / 2, "Top angle must be > 90 degrees"
         assert self.side_guard_channel_radius > self.radius_lower
 
+        assert self.front_wing_angle < 180 / self.facets
+        assert self.front_wing_dh + self.front_wing_height < self.height
+
     @property
     def facet_width_lower(self):
         return self.base_circ / self.facets
@@ -59,6 +78,16 @@ class Crown(Model):
     def radius_upper(self):
         return (self.tilt_circ + (self.tilt_circ - self.base_circ)) / (2 * math.pi)
 
+    @property
+    def radius_lower_front(self):
+        return self.front_base_circ / (2 * math.pi)
+    @property
+    def radius_middle_front(self):
+        return self.radius_lower_front + (self.radius_middle - self.radius_lower)
+    @property
+    def radius_upper_front(self):
+        return self.radius_lower_front + (self.radius_upper - self.radius_lower)
+
     def profile_base(self) -> Cq.Sketch:
         # Generate the pentagonal shape
 
@@ -383,12 +412,42 @@ class Crown(Model):
             (0,0,dx + self.side_guard_dovetail_height),
         ).moved((0, 0, -dx))
 
-    def side_guard(self, attach_left: AttachPoint, attach_right: AttachPoint) -> Cq.Workplane:
+    def side_guard_frontal_slot(self) -> Cq.Workplane:
+        angle = 360 / self.facets
+        outer = Cq.Solid.makeCone(
+            radius1=self.radius_lower_front + self.thickness,
+            radius2=self.radius_upper_front + self.thickness,
+            height=self.height,
+            angleDegrees=angle,
+        )
+        inner = Cq.Solid.makeCone(
+            radius1=self.radius_lower_front,
+            radius2=self.radius_upper_front,
+            height=self.height,
+            angleDegrees=angle,
+        )
+        shell = (
+            outer.cut(inner)
+            .rotate((0,0,0), (0,0,1), -angle/2)
+        )
+        # Generate the sector intersector
+        intersector = Cq.Solid.makeCylinder(
+            radius=self.radius_upper + self.side_guard_thickness,
+            height=self.front_wing_height,
+            angleDegrees=self.front_wing_angle,
+        ).moved(Cq.Location(0,0,self.front_wing_dh,0,0,-self.front_wing_angle/2))
+        return shell * intersector
+
+    def side_guard(
+            self,
+            attach_left: AttachPoint,
+            attach_right: AttachPoint,
+        ) -> Cq.Workplane:
         """
         Constructs the side guard using a cone. Via Gauss's Theorema Egregium,
         the surface of the cone can be deformed into a plane.
         """
-        angle_span = 360 / 5
+        angle_span = 360 / self.facets
         outer = Cq.Solid.makeCone(
             radius1=self.radius_lower + self.side_guard_thickness,
             radius2=self.radius_upper + self.side_guard_thickness,
@@ -426,15 +485,20 @@ class Crown(Model):
         #    )
         #)
         result = shell * profile# - channel
-        for i in [-2, -1, 0, 1, 2]:
+
-            phi = i * (math.pi / 14)
+        # Create the slots
-            hole = Cq.Solid.makeCylinder(
+        for sign in [-1, 1]:
-                radius=self.side_guard_hole_diam / 2,
+            slot = Cq.Solid.makeBox(
-                height=self.radius_upper * 2,
+                length=self.height,
-                pnt=(0, 0, self.side_guard_hole_height),
+                width=self.slot_width,
-                dir=(math.cos(phi), math.sin(phi), 0),
+                height=self.slot_thickness,
+            ).moved(
+                Cq.Location.rot2d(sign * self.side_guard_slot_angle) *
+                Cq.Location(self.radius_lower + self.side_guard_thickness/2, 0, 0) *
+                Cq.Location(0,0,0,0,-180 + self.slot_tilt,0) *
+                Cq.Location(-self.slot_thickness,-self.slot_width/2, -self.slot_thickness/2)
             )
-            result = result - hole
+            result = result - slot
 
         radius_attach = self.radius_lower + self.side_guard_thickness / 2
         # tilt the dovetail by radius differential
@@ -443,12 +507,15 @@ class Crown(Model):
         loc_dovetail_left = Cq.Location.rot2d(angle_span / 2) * Cq.Location(radius_attach, 0, 0, 0, angle_tilt, 0)
         loc_dovetail_right = Cq.Location.rot2d(-angle_span / 2) * Cq.Location(radius_attach, 0, 0, 0, angle_tilt, 0)
 
+        angle_slot = 180 / self.facets - self.front_wing_angle / 2
         match attach_left:
             case AttachPoint.DOVETAIL_IN:
                 loc_dovetail_left *= Cq.Location.rot2d(180)
                 result = result - dovetail.moved(loc_dovetail_left)
             case AttachPoint.DOVETAIL_OUT:
                 result = result + dovetail.moved(loc_dovetail_left)
+            case AttachPoint.SLOT:
+                result = result - self.side_guard_frontal_slot().moved(Cq.Location.rot2d(angle_slot))
             case AttachPoint.NONE:
                 pass
         match attach_right:
@@ -457,6 +524,8 @@ class Crown(Model):
             case AttachPoint.DOVETAIL_OUT:
                 loc_dovetail_right *= Cq.Location.rot2d(180)
                 result = result + dovetail.moved(loc_dovetail_right)
+            case AttachPoint.SLOT:
+                result = result - self.side_guard_frontal_slot().moved(Cq.Location.rot2d(-angle_slot))
             case AttachPoint.NONE:
                 pass
         # Remove parts below the horizontal
@@ -466,6 +535,12 @@ class Crown(Model):
             height=cut_h).moved((0,0,-cut_h))
         return result
 
+    @target(name="side_guard_1")
+    def side_guard_1(self) -> Cq.Workplane:
+        return self.side_guard(
+            attach_left=AttachPoint.SLOT,
+            attach_right=AttachPoint.DOVETAIL_IN,
+        )
     @target(name="side_guard_2")
     def side_guard_2(self) -> Cq.Workplane:
         return self.side_guard(
@@ -475,9 +550,15 @@ class Crown(Model):
     @target(name="side_guard_3")
     def side_guard_3(self) -> Cq.Workplane:
         return self.side_guard(
-            attach_left=AttachPoint.DOVETAIL_IN,
+            attach_left=AttachPoint.DOVETAIL_OUT,
             attach_right=AttachPoint.DOVETAIL_IN,
         )
+    @target(name="side_guard_3")
+    def side_guard_4(self) -> Cq.Workplane:
+        return self.side_guard(
+            attach_left=AttachPoint.DOVETAIL_OUT,
+            attach_right=AttachPoint.SLOT,
+        )
 
     def front_surrogate(self) -> Cq.Workplane:
         """
@@ -486,14 +567,14 @@ class Crown(Model):
         """
         angle = 360 / 5
         outer = Cq.Solid.makeCone(
-            radius1=self.radius_lower + self.thickness,
+            radius1=self.radius_lower_front + self.thickness,
-            radius2=self.radius_upper + self.thickness,
+            radius2=self.radius_upper_front + self.thickness,
             height=self.height,
             angleDegrees=angle,
         )
         inner = Cq.Solid.makeCone(
-            radius1=self.radius_lower,
+            radius1=self.radius_lower_front,
-            radius2=self.radius_upper,
+            radius2=self.radius_upper_front,
             height=self.height,
             angleDegrees=angle,
         )
@@ -501,7 +582,7 @@ class Crown(Model):
             outer.cut(inner)
             .rotate((0,0,0), (0,0,1), -angle/2)
         )
-        dx = math.sin(math.radians(angle / 2)) * self.radius_middle
+        dx = math.sin(math.radians(angle / 2)) * self.radius_middle_front
         profile = (
             Cq.Workplane('YZ')
             .polyline([
@@ -512,7 +593,7 @@ class Crown(Model):
                 (dx, self.height / 2),
             ])
             .close()
-            .extrude(self.radius_upper + self.side_guard_thickness)
+            .extrude(self.radius_upper_front + self.side_guard_thickness)
             .val()
         )
         return shell * profile
@@ -521,14 +602,20 @@ class Crown(Model):
         """
         New assembly using conformal mapping on the cone.
         """
-        side_guard = self.side_guard_2()
+        side_guards = [
+            self.side_guard_1(),
+            self.side_guard_2(),
+            self.side_guard_3(),
+            self.side_guard_4(),
+        ]
         a = Cq.Assembly()
-        for i in range(1,5):
+        for i,side_guard in enumerate(side_guards):
+            angle = -(i+1) * 360 / self.facets
             a = a.addS(
                 side_guard,
                 name=f"side-{i}",
                 material=self.material_side,
-                loc=Cq.Location(rz=i*360/5)
+                loc=Cq.Location(rz=angle)
             )
         a.addS(
             self.front_surrogate(),