octathingy: tweak some dimensions, add screw holes for securing both halves of the core sphere instead of gluing them together (makes it possible to repair or replace a capsule)

Octathingy_common.scad

@@ -179,37 +179,39 @@ module capsule_holder(ratio, transition, hollow = true) {
         cylinder(r = capsule_radius + fudge + wall, h = capsule_h, $fn = cfacets);
         if (hollow) cylinder(r = capsule_radius + fudge, h = capsule_h + thin_mint, $fn = cfacets);
     }
-    // transition into core holder
+    // conical transition into core sphere
     transition_h = transition * capsule_radius;
     translate([0, 0, - transition_h]) {
         difference() {
             cylinder(r2 = capsule_radius + fudge + wall, r1 = (capsule_radius) * ratio + wall, h = transition_h, $fn = facets);
-            // add overhang so that we have a stop for the capsule
+            // add overhang so that we have a stop when inserting the capsule
             overhang = 0.2;
             if (hollow) cylinder(r2 = capsule_radius + fudge - overhang, r1 = (capsule_radius) * ratio, h = transition_h, $fn = facets);
-            // add holes in the walls of the transition
+            // add holes in the walls of the conical transition
             if (hollow) {
                 for (r = [0:36:179]) {
                     rotate([0, 90, r]) {
                         translate([-transition_h, 0, -capsule_radius - 2 * wall])
-                            scale([7, 1.4, 1]) cylinder(r = 1.0, h = (capsule_radius + 2 * wall) * 2, $fn = facets);
+                            scale([7, 1.3, 1]) cylinder(r = 1.0, h = (capsule_radius + 2 * wall) * 2, $fn = facets);
                     }
                 }
             }
         }
         // lip to insert holder into core
-        lip_d = 1.5 * wall;
+        lip_d = 1.4 * wall;
         translate([0, 0, hollow == false ? -3 : -lip_d]) {
             difference() {
                 // if not hollow make the ring longer to cut into core
                 cylinder(r = (capsule_radius) * ratio + wall + (hollow == true ? 0 : fit/2),
                         h = hollow == true ? lip_d : 4.0, $fn = facets);
-                if (hollow) { cylinder(r = capsule_cable_diam/2 * 1.5, h = lip_d + thin_mint, $fn = facets); }
+                if (hollow) { cylinder(r = capsule_cable_diam/2 * 1.4, h = lip_d + thin_mint, $fn = facets); }
             }
         }
     }
 }
 
+// capsule holder array
+//
 module capsule_holder_array(hollow = true) {
     for (az = [45, 135, -45, -135]) {
         rotate([0, elev_angle, az]) {
@@ -225,23 +227,44 @@ module capsule_holder_array(hollow = true) {
     }
 }
 
-// the core
-// render = 0: the sphere
+// the spherical core and mounting stalk
+//
+// render = 0: the full sphere (for visualization)
 // render = 1: upper half
-// render = -1: lower half
+// render = -1: lower half with stalk
+
+// thinkness of ring that connects both halves of the core sphere
+core_ring_height = 5.0;
+
+// holes for screws that hold together both halves of the sphere
+module capsule_holder_screws(radius, wall) {
+    h_offset = 1.2;
+        for (r = [90, 270]) {
+            for (t = [0, 45]) {
+                m = t > 0 ? 1 : 0;
+                // 11.5 matches the angle for the flat shaves in the core
+                mirror([0, 0, m]) rotate([0, 11.5, r + t]) translate([-(radius + 2 * wall), 0, 0]) {
+                    rotate([0, 90, 0]) {
+                        cylinder(r = 0.65, h = radius, $fn = facets);
+                    }
+                }
+            }
+        }
+}
 
+// ring that holds the two halves of the sphere together
 module capsule_holder_ring(offset = 3.5) {
     s_radius = mic_radius - capsule_radius * (1 + transition_ratio) + offset;
-    ring_h = 3.0;
-    difference() {
+    ring_h = core_ring_height - 0.2;
+    translate([0, 0, -ring_h/2]) difference() {
         cylinder(r = s_radius - 2.5 * wall - fit, h = ring_h, $fn = facets);
         cylinder(r = s_radius - 4 * wall - fit, h = ring_h, $fn = facets);
+        translate([0, 0, ring_h/2]) capsule_holder_screws(s_radius, wall);
     }
 }
-module capsule_holder_core(render = 0, offset = 3.5) {
-    // XXX need to turn this into a parameter
-    top_radius = mount_radius + wall;
 
+// spherical core
+module capsule_holder_core(top_radius, render = 0, offset = 3.5) {
     s_radius = mic_radius - capsule_radius * (1 + transition_ratio) + offset;
     difference() {
         union() {
@@ -249,6 +272,8 @@ module capsule_holder_core(render = 0, offset = 3.5) {
                 // core
                 sphere(r = s_radius, $fn = facets);
                 sphere(r = s_radius - 2.5 * wall, $fn = facets);
+                // holes for screws
+                capsule_holder_screws(s_radius, wall);
                 // remove slice at the top
                 translate([-s_radius, -s_radius, s_radius - wall]) {
                     cube([2 * s_radius, 2 * s_radius, s_radius]);
@@ -272,7 +297,7 @@ module capsule_holder_core(render = 0, offset = 3.5) {
                     translate([-mic_radius, -mic_radius, 0]) cube([mic_radius * 2, mic_radius * 2, mic_radius * 2]);
                 }
                 // make space for connection ring
-                ring_h = 3.0;
+                ring_h = core_ring_height;
                 translate([0, 0, -ring_h/2]) {
                     cylinder(r = s_radius - 2.5 * wall, h = ring_h, $fn = facets);
                 }