itx-aperture-grommet: wip

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/itx-aperture-grommet.scad b/itx-aperture-grommet.scad
new file mode 100644 (file)
index 0000000..badb4ab
--- /dev/null
+++ b/itx-aperture-grommet.scad
@@ -0,0 +1,56 @@
+// -*- C -*-
+
+include <utils.scad>
+include <threads.scad>
+
+ap_width = 21.30;
+ap_height = 16.45;
+tot_height = 22.74;
+screw_ctr_to_tr = [ 7.89, 3.87 ];
+
+tab_th = 2.5;
+wall_th = 1;
+wall_h = 1;
+
+app_slop = 0.60; // total across both sides
+
+// calculated
+
+tab_h = tot_height - ap_height;
+
+real_ap_sz = [ ap_width, ap_height ] - app_slop * [ 1,1 ];
+real_main_sz = real_ap_sz + wall_th * [ 2,1 ];
+real_all_sz = real_main_sz + tab_h * [0,1];
+
+screw_pos = real_all_sz - (screw_ctr_to_tr - 0.5 * app_slop * [1,1]);
+
+module GapPlan() {
+  rectfromto([ wall_th, -1 ],
+            [ real_main_sz[0] - wall_th, real_ap_sz[1] - wall_th ]);
+}
+
+module MainPlan() {
+  rectfromto([0,0],
+            real_main_sz);
+}
+
+module AllPlan() {
+  rectfromto([0,0], real_all_sz);
+}
+
+module Grommet(){ ////toplevel
+  difference(){
+    union(){
+      linextr(0, tab_th + wall_h) MainPlan();
+      linextr(0, tab_th) AllPlan();
+    }
+    linextr(-1, tab_th + wall_h + 1) GapPlan();
+    translate(concat(screw_pos, [-1]))
+      english_thread(diameter = 0.1380,
+                    threads_per_inch = 32,
+                    length = tab_th + 2,
+                    internal = true);
+  }
+}
+
+Grommet();