cad(enclosure): add bottom standoffs, cam interfaces, spring posts

Author: KilowattSynthesis

cad/column_rod_enclosure.py

@@ -9,14 +9,16 @@
 * In each corner:
     * Anchor an M2 or M3 screw through the top and bottom enclosures.
     * Use fixed metal rods/bolts in each corner of the enclosure.
-    * Use springs pushing up on the PCB to keep the dots in the "raised" position for
-        most CAM positions.
-    * Use the cams to push the PCB down against the springs (cams push against the top
-        plate) to lower into the "adjust positions" state.
+    * Use springs pushing down on the PCB to keep the dots in the "lowered" position for
+        most CAM positions. Do this because the spring is bulky, and therefore should go
+        on the top side.
+    * Use the cams to push the PCB up against the springs (cams push against the bottom
+        plate) to raise into the "feel the dots now" state.
 """
 
 import copy
 import json
+import math
 from dataclasses import dataclass
 from datetime import UTC, datetime
 from itertools import product
@@ -42,10 +44,15 @@ class Spec:
 
     pcb_length_x: float = 95
     pcb_length_y: float = 99
-    # PCB + Housing + Screw_Heads -or- PCB + Raiser_Motor_OD + Raiser_Motor_Clip
-    pcb_and_housing_thickness_z: float = 1.6 + 6.0 + 1.0
-    pcb_travel_z: float = 2
-    pcb_extra_z: float = 3  # Extra dist in Z, for housing-to-PCB screw heads.
+
+    # Settings controlling the Z travel of the PCB inside in the enclosure.
+    pcb_thickness: float = 0.8
+    cam_motor_od: float = 6.0
+    cam_motor_clamp_top_thickness_plus_bolt_heads: float = 1.5 + 4
+    pcb_travel_z: float = 1.2
+    cam_min_od: float = 7.4
+    cam_max_od: float = 8.6
+    cam_avg_od: float = 8.0
 
     # PCB layout - corner screws.
     pcb_raiser_screw_sep_x: float = 42.6
@@ -65,11 +72,26 @@ class Spec:
     rp2040_cutout_x_range: tuple[float, float] = (18, 400)
     rp2040_cutout_y_range: tuple[float, float] = (-26, 15)
 
+    # PCB layout - where do the parts that interface with the cams go?
+    # These cam interfaces are drawn on the inside of the bottom wall.
+    cam_interface_x_sep: float = 64.2  # 163.6 - 99.4
+    cam_interface_y_sep: float = 79.0  # 164 - 85
+    cam_interface_width_x: float = 2.0
+    cam_interface_width_y: float = 8.0
+
+    # PCB layout - where do the spring posts go?
+    # These spring posts are drawn on the inside of the top wall.
+    spring_post_od = 3.5  # TODO(KS): Check spring ID.
+    spring_post_margin_from_pcb_edge: float = 3.0  # Dist: PCB edge to center of post.
+
+    # Overall enclosure dimensions.
     enclosure_total_x: float = 130
     enclosure_total_y: float = 125
     enclosure_wall_thickness_xy: float = 2.2
     enclosure_wall_thickness_bottom: float = 2
     enclosure_wall_thickness_top: float = 2
+    enclosure_bottom_wall_standoff_height: float = 4.0  # Avoid THT solder points, nuts.
+    enclosure_bottom_wall_standoff_od: float = 6
 
     # Bolts for joining the top/bottom halves of the enclosure securely.
     joiner_bolt_d: float = 3  # M3.
@@ -78,27 +100,61 @@ class Spec:
 
     enclosure_fillet_radius_xy: float = 2
 
+    bottom_debugging_hole_od: float = 60.0
+
     def __post_init__(self) -> None:
         """Post initialization checks."""
         data = {
+            "pcb_and_housing_thickness_z": self.pcb_and_housing_thickness_z,
             "enclosure_total_z": self.enclosure_total_z,
+            "spring_post_length": self.spring_post_length,
         }
         logger.info(json.dumps(data, indent=2))
 
+        assert math.isclose(
+            self.cam_max_od - self.cam_min_od,
+            self.pcb_travel_z,
+        )
+
+        assert math.isclose(
+            (self.cam_min_od + self.cam_max_od) / 2,
+            self.cam_avg_od,
+        )
+
     def deep_copy(self) -> "Spec":
         """Copy the current spec."""
         return copy.deepcopy(self)
 
+    @property
+    def pcb_and_housing_thickness_z(self) -> float:
+        """Max thickness from the bottom of the PCB to the inside of the enclosure."""
+        # TODO(KilowattSynthesis): Update to be max(housing_height, raiser_height)
+
+        # housing_height = PCB + Housing + Screw_Heads
+        # raiser_height = PCB + Raiser_Motor_OD + Raiser_Motor_Clip (this one)
+        raiser_height = (
+            self.cam_motor_clamp_top_thickness_plus_bolt_heads
+            + self.cam_motor_od
+            + self.pcb_thickness
+        )
+        return raiser_height
+
     @property
     def enclosure_total_z(self) -> float:
         """Total thickness of the enclosure."""
         return (
             self.enclosure_wall_thickness_bottom
+            + self.enclosure_bottom_wall_standoff_height
             + self.pcb_and_housing_thickness_z
             + self.pcb_travel_z
             + self.enclosure_wall_thickness_top
         )
 
+    @property
+    def spring_post_length(self) -> float:
+        """Length of the spring posts."""
+        return self.pcb_and_housing_thickness_z - self.pcb_thickness
+
     def get_cell_center_x_values(self) -> list[float]:
         """Get the X coordinate of the center of each cell."""
         return bde.evenly_space_with_center(
@@ -151,10 +207,11 @@ def make_enclosure_top(spec: Spec) -> bd.Part | bd.Compound:
     )
 
     # Remove the inside of the enclosure.
+    inside_of_box_z_val = spec.enclosure_total_z - spec.enclosure_wall_thickness_top
     inner_box = bd.Box(
         spec.enclosure_total_x - 2 * spec.enclosure_wall_thickness_xy,
         spec.enclosure_total_y - 2 * spec.enclosure_wall_thickness_xy,
-        spec.enclosure_total_z - spec.enclosure_wall_thickness_top,
+        inside_of_box_z_val,
         align=bde.align.ANCHOR_BOTTOM,
     )
     p -= bd.fillet(
@@ -217,6 +274,34 @@ def make_enclosure_top(spec: Spec) -> bd.Part | bd.Compound:
         range_z=(-50, 50),
     )
 
+    # Add spring posts.
+    spring_post_y_max = inside_of_box_z_val
+    # spring_post_y_min = (  # Old complex logic before simplification by substitution.
+    #     spec.enclosure_wall_thickness_bottom
+    #     + spec.enclosure_bottom_wall_standoff_height
+    #     + spec.pcb_thickness
+    #     + spec.pcb_travel_z
+    # )
+    for x_corner, y_corner in product((1, -1), (1, -1)):
+        for x_small_multiplier, y_small_multiplier in ((1, 0), (0, 1)):
+            p += bd.Pos(
+                x_corner
+                * (
+                    spec.pcb_length_x / 2
+                    - spec.spring_post_margin_from_pcb_edge * x_small_multiplier
+                ),
+                y_corner
+                * (
+                    spec.pcb_length_y / 2
+                    - spec.spring_post_margin_from_pcb_edge * y_small_multiplier
+                ),
+                spring_post_y_max,
+            ) * bd.Cylinder(
+                radius=spec.spring_post_od / 2,
+                height=spec.spring_post_length,
+                align=bde.align.ANCHOR_TOP,
+            )
+
     return p
 
 
@@ -235,7 +320,7 @@ def make_enclosure_bottom(spec: Spec) -> bd.Part | bd.Compound:
         inner_box.edges().filter_by(bd.Axis.Z), radius=spec.enclosure_fillet_radius_xy
     )
 
-    # Add the `joiner_bolt` (top-to-bottom connections).
+    # Remove the `joiner_bolt` holes (sturdy top-to-bottom connections) in corners.
     for x_sign, y_sign in product((1, -1), (1, -1)):
         bottom_of_joiner_bolt_pos = bd.Pos(
             x_sign * (spec.enclosure_total_x / 2 - spec.joiner_bolt_margin),
@@ -247,6 +332,14 @@ def make_enclosure_bottom(spec: Spec) -> bd.Part | bd.Compound:
             align=bde.align.ANCHOR_BOTTOM,
         )
 
+    # Add the stand offs from the bottom wall.
+    for x_val, y_val in spec.get_pcb_raiser_screw_coordinates():
+        p += bd.Pos(x_val, y_val, spec.enclosure_wall_thickness_bottom) * bd.Cylinder(
+            radius=spec.enclosure_bottom_wall_standoff_od / 2,
+            height=spec.enclosure_bottom_wall_standoff_height,
+            align=bde.align.ANCHOR_BOTTOM,
+        )
+
     # Remove the holes for the `pcb_raiser_screw`.
     for x_val, y_val in spec.get_pcb_raiser_screw_coordinates():
         p -= bd.Pos(x_val, y_val, 0) * bd.Cylinder(
@@ -255,15 +348,48 @@ def make_enclosure_bottom(spec: Spec) -> bd.Part | bd.Compound:
             align=bde.align.ANCHOR_BOTTOM,
         )
 
+    # Add the cam interfaces.
+    # Set this height such that, at the chosen cam state, it is statically determinate
+    # against the standoffs on the bottom.
+    cam_interface_z_min = spec.enclosure_wall_thickness_bottom
+    cam_interface_height = (
+        spec.enclosure_bottom_wall_standoff_height
+        + spec.pcb_thickness
+        + spec.cam_motor_od / 2
+        - spec.cam_max_od / 2  # TODO(KS): Not sure what to pick. Min or max for sure.
+    )
+    for x_sign, y_sign in product((1, -1), (1, -1)):
+        p += bd.Pos(
+            x_sign * spec.cam_interface_x_sep / 2,
+            y_sign * spec.cam_interface_y_sep / 2,
+            cam_interface_z_min,
+        ) * bd.Box(
+            spec.cam_interface_width_x,
+            spec.cam_interface_width_y,
+            cam_interface_height,
+            align=bde.align.ANCHOR_BOTTOM,
+        )
+
+    # Remove giant debugging hole.
+    if spec.bottom_debugging_hole_od > 0.2:  # noqa: PLR2004
+        p -= bd.Cylinder(
+            radius=spec.bottom_debugging_hole_od / 2,
+            height=10,
+        )
+
     return p
 
 
 def preview_both_enclosure_parts(spec: Spec) -> bd.Part | bd.Compound:
     """Preview both the top and bottom enclosure parts."""
     p = bd.Part(None)
 
-    p += make_enclosure_top(spec).translate((0, 0, 3))
-    p += make_enclosure_bottom(spec).translate((0, 0, -3))
+    enclosure_top = make_enclosure_top(spec).translate((0, 0, 3))
+    enclosure_bottom = make_enclosure_bottom(spec).translate((0, 0, -13))
+
+    # Debugging: Add a breakpoint on the next line.
+    p += enclosure_top
+    p += enclosure_bottom
 
     return p
 

cad/pcb_raiser_cam.py

@@ -60,7 +60,10 @@ class MainSpec:
 
     def __post_init__(self) -> None:
         """Post initialization checks."""
-        data = {}
+        data = {
+            "cam_min_od": self.cam_main_od - self.cam_travel / 2,
+            "cam_max_od": self.cam_main_od + self.cam_travel / 2,
+        }
         logger.info(json.dumps(data, indent=2))
 
     def deep_copy(self) -> "MainSpec":
@@ -204,15 +207,25 @@ def make_assembly_cam_and_dc_motor(spec: MainSpec) -> bd.Part | bd.Compound:
     return p
 
 
+def preview_all() -> bd.Part | bd.Compound:
+    """Preview all the parts defined here."""
+    p = bd.Part(None)
+    p += make_cam(MainSpec()).translate((0, 0, 0))
+    p += make_dc_motor_and_gearbox(MotorMainSpec()).translate((10, 0, 0))
+    p += make_bushing_block(MainSpec()).translate((20, 0, 0))
+    return p
+
+
 if __name__ == "__main__":
     start_time = datetime.now(UTC)
     py_file_name = Path(__file__).name
     logger.info(f"Running {py_file_name}")
 
     parts = {
-        "cam": show(make_cam(MainSpec())),
-        "assembly_cam_and_dc_motor": show(make_assembly_cam_and_dc_motor(MainSpec())),
-        "bushing_block": show(make_bushing_block(MainSpec())),
+        "preview_all": show(preview_all()),
+        "cam": (make_cam(MainSpec())),
+        "assembly_cam_and_dc_motor": (make_assembly_cam_and_dc_motor(MainSpec())),
+        "bushing_block": (make_bushing_block(MainSpec())),
     }
 
     logger.info("Saving CAD model(s)...")