itx-aperture-grommet.scad

   1 // -*- C -*-
   2
   3 include <utils.scad>
   4 include <threads.scad>
   5
   6 ap_width = 21.30;
   7 ap_height = 16.45;
   8 tot_height = 22.74 + 1.0;
   9 screw_ctr_to_tr = [ 7.89, 3.87 ];
  10
  11 tab_th = 2.5;
  12 wall_th = 1;
  13 wall_h = 2;
  14
  15 app_slop = 0.60; // total across both sides
  16
  17 // calculated
  18
  19 tab_h = tot_height - ap_height;
  20
  21 real_main_sz = [ ap_width, ap_height ] - app_slop * [ 1,1 ];
  22 real_all_sz = real_main_sz + tab_h * [0,1];
  23 real_inner_sz = real_main_sz - wall_th * [ 2,1 ];
  24
  25 screw_pos = real_all_sz - (screw_ctr_to_tr - 0.5 * app_slop * [1,1]);
  26
  27 module GapPlan() {
  28   rectfromto([ wall_th, -1 ],
  29              real_main_sz - wall_th * [1,1]);
  30 }
  31
  32 module MainPlan() {
  33   rectfromto([0,0],
  34              real_main_sz);
  35 }
  36
  37 module AllPlan() {
  38   rectfromto([0,0], real_all_sz);
  39 }
  40
  41 module Grommet(){ ////toplevel
  42   difference(){
  43     union(){
  44       linextr(0, tab_th + wall_h) MainPlan();
  45       linextr(0, tab_th) AllPlan();
  46     }
  47     linextr(-1, tab_th + wall_h + 1) GapPlan();
  48     translate(concat(screw_pos, [-1]))
  49       english_thread(diameter = 0.1380,
  50                      threads_per_inch = 32,
  51                      length = tab_th + 2,
  52                      internal = true);
  53   }
  54 }
  55
  56 Grommet();