fix: flip dovetail receiver onto case

hardware/README.md

@@ -105,8 +105,8 @@ The ESP8266 and GoPro talk over Wi-Fi — **no data cable between them**. The on
 
 | | W × D × H (mm) |
 |---|---|
-| Case body external | ~56.8 × 38.2 × 19.0 |
+| Case body external | ~56.8 × 42.0 × 19.2 |
 | Lid external | ~56.8 × 32.8 × 4.0 |
-| Tripod clamp | ~43.0 × 56.9 × 16.0 |
+| Tripod clamp | ~43.0 × 54.5 × 16.0 |
 | Clamp pole fit | Nominal 35mm; smaller poles TBD / may need inserts |
 | Total weight | TBD after prototype print |

hardware/case/tripod-case-v3.scad

@@ -30,13 +30,13 @@ m3_clearance  = 3.4;      // M3 screw clearance
 nut_flat      = 6.4;      // M3 nut trap flat-to-flat
 
 // Dovetail slide interface
-// Male rail is on the case; matching female socket is on the tripod clamp.
-// This is easier to inspect and avoids the previous mismatched "two lips + tab" geometry.
+// Female receiver is on the case; male tab is on the tripod clamp.
+// This makes the separate parts visually/physically obvious: tab slides into slot.
 rail_z         = outer_h * 0.78;
 rail_depth     = 5.0;
-rail_neck_w    = 12.0;   // narrow width at case wall / slot opening
-rail_outer_w   = 18.0;   // wider retained edge
-rail_clearance = 0.45;   // FDM sliding clearance per side-ish
+rail_neck_w    = 12.0;   // narrow side of the trapezoid profile
+rail_outer_w   = 18.0;   // wide side of the trapezoid profile
+rail_clearance = 0.55;   // FDM sliding clearance
 socket_wall    = 2.2;
 
 // Cable ports
@@ -107,15 +107,30 @@ module screw_post(x, y) {
     }
 }
 
-module case_male_dovetail_rail() {
-    // Positive tapered rail on the case back. Cross-section is narrow at the
-    // wall and wider at the outside, so the clamp socket captures it.
-    translate([0, outer_d/2 - 0.15, outer_h/2])
-        dovetail_prism(rail_z, rail_neck_w, rail_outer_w, rail_depth);
+module case_dovetail_socket() {
+    // Receiver boss on the case back. A dovetail-shaped through-slot is cut
+    // vertically through it so the clamp's male tab slides down from above.
+    socket_outer_w = rail_outer_w + socket_wall*2;
+    socket_depth   = rail_depth + socket_wall*2;
+    boss_y0        = outer_d/2 - 0.15;
 
-    // Bottom stop so the clamp socket cannot slide past the case.
-    translate([0, outer_d/2 + rail_depth/2, outer_h*0.12])
-        rounded_cube_centered(rail_outer_w + 3.0, rail_depth + 0.8, 2.4, 0.8);
+    difference() {
+        translate([0, boss_y0 + socket_depth/2, outer_h/2])
+            rounded_cube_centered(socket_outer_w, socket_depth, rail_z + socket_wall*2, 1.2);
+
+        // Through-cut, centered within the receiver boss, oversized for FDM.
+        translate([0, boss_y0 + socket_wall, outer_h/2])
+            dovetail_prism(
+                rail_z + socket_wall*3,
+                rail_neck_w + rail_clearance,
+                rail_outer_w + rail_clearance,
+                rail_depth + rail_clearance
+            );
+    }
+
+    // Bottom stop shelf: clamp tab slides down until it rests here.
+    translate([0, boss_y0 + socket_depth/2, outer_h*0.08])
+        rounded_cube_centered(socket_outer_w, socket_depth, 1.8, 0.8);
 }
 
 module case_body() {
@@ -123,7 +138,7 @@ module case_body() {
         case_shell();
         for (x = [-1, 1], y = [-1, 1])
             screw_post(x*(outer_w/2 - 5), y*(outer_d/2 - 5));
-        case_male_dovetail_rail();
+        case_dovetail_socket();
     }
 }
 
@@ -174,33 +189,25 @@ module clamp_ears() {
     }
 }
 
-module clamp_dovetail_socket() {
+module clamp_male_dovetail_tab() {
     outer_r = pole_dia/2 + clamp_thick;
-    socket_outer_w = rail_outer_w + socket_wall*2;
-    socket_depth   = rail_depth + socket_wall*2;
 
-    // Solid boss on the rear of the clamp, opposite the tightening mouth.
-    // A matching dovetail void is cut through it along Z so the case rail
-    // slides in from the top/bottom with practical FDM clearance.
-    difference() {
-        translate([0, -outer_r - socket_depth/2 + socket_wall, 0])
-            rounded_cube_centered(socket_outer_w, socket_depth, clamp_width, 1.2);
-
-        translate([0, -outer_r - 0.15, 0])
-            dovetail_prism(
-                clamp_width + 1.0,
-                rail_neck_w + rail_clearance,
-                rail_outer_w + rail_clearance,
-                rail_depth + 0.6
-            );
-    }
+    // Positive tab on rear of clamp, opposite the tightening mouth. This is
+    // intentionally the moving/replaceable side: it slides into the case socket.
+    translate([0, -outer_r - rail_depth + 0.2, 0])
+        dovetail_prism(
+            rail_z - rail_clearance,
+            rail_neck_w - rail_clearance,
+            rail_outer_w - rail_clearance,
+            rail_depth - 0.25
+        );
 }
 
 module tripod_clamp() {
     union() {
         clamp_ring_with_mouth();
         clamp_ears();
-        clamp_dovetail_socket();
+        clamp_male_dovetail_tab();
     }
 }