topeak-mtx-tortec-expeditionrack-adapter.scad

   1 // -*- C -*-
   2
   3 // brk_*: "bracket", the Topeak MTX bracket
   4 // rack_*: the Tortec rack
   5 // adapt_*: the adapter, ie this file
   6
   7 include <utils.scad>
   8
   9 brk_recess_actual = 5.20;
  10
  11 rack_rail_dia = 10.40 + 0.50;
  12 rack_width_inner = 115.86 + 1.0; // between insides of rails
  13
  14 rear_elevation_nominal = 10.04; // top of rack to bottom of bracket
  15 rear_to_front_distance = 230;
  16
  17 general_gap_y = 1.0;
  18
  19 main_sz_z = 20; // xxx
  20 main_sz_y = 20;
  21 grasp_sz = 12;
  22
  23 // calculated
  24
  25 brk_bottom_y = -brk_recess_actual;
  26 adapt_main_top_y = brk_bottom_y + general_gap_y;
  27
  28 // on LHS, so -ve
  29 rack_rail_x = -(rack_width_inner/2 + rack_rail_dia/2);
  30 rack_rail_outer_x = -(rack_width_inner/2 + rack_rail_dia);
  31
  32 grasp_large_r = (rack_rail_dia + grasp_sz)/2;
  33 grasp_large_x = rack_rail_outer_x + grasp_large_r;
  34
  35 block_x = grasp_large_x + grasp_large_r/2;
  36 block_y_min = adapt_main_top_y - main_sz_y;
  37
  38 module GraspElevation(){
  39   hull(){
  40     translate([ grasp_large_x, adapt_main_top_y - grasp_large_r ])
  41       circle(grasp_large_r);
  42
  43     translate([ grasp_large_x, $rack_rail_y - rack_rail_dia/2 ])
  44       circle(grasp_large_r);
  45
  46     translate([ grasp_large_x, $rack_rail_y + rack_rail_dia/2 ])
  47       circle(grasp_large_r);
  48   }
  49 }
  50
  51 module BlockElevation(){
  52   rectfromto([ +block_x, adapt_main_top_y ],
  53              [ -block_x, block_y_min ]);
  54 }
  55
  56 module GraspFixingElevation(){
  57   intersection(){
  58     mirror([1,0]) GraspElevation();
  59     union(){
  60       rectfromto([0, $rack_rail_y],
  61                  [rack_width_inner, 50]);
  62       intersection(){
  63         translate([ rack_rail_x, $rack_rail_y ])
  64           circle(r = rack_width_inner/2 - rack_rail_x, $fa=1);
  65         polygon([ [ 0, 0 ],
  66                   [ rack_width_inner/2, 0 ],
  67                   [ rack_width_inner/2, $rack_rail_y - rack_rail_dia/2 ],
  68                   [ -block_x, block_y_min ],
  69                   [ 0, block_y_min ]]);
  70       }
  71     }
  72   }
  73 }
  74
  75 module Principal(){
  76   // calculated
  77   $rack_rail_y = brk_bottom_y - $elevation_nominal
  78     - general_gap_y  - rack_rail_dia/2;
  79
  80   difference(){
  81     linextr(0, main_sz_z){
  82       GraspElevation();
  83       BlockElevation();
  84       GraspFixingElevation();
  85     }
  86
  87     linextr(-10, main_sz_z+10) {
  88       for (mx=[0,1]) {
  89         mirror([mx,0]) {
  90           translate([ rack_rail_x, $rack_rail_y ]){
  91             hull(){
  92               for (dx = [-rack_rail_dia, 0])
  93                 translate([dx, 0])
  94                   circle(r= rack_rail_dia/2);
  95             }
  96           }
  97         }
  98       }
  99     }
 100   }
 101 }
 102
 103 Principal($elevation_nominal=0);