3 // brk_*: "bracket", the Topeak MTX bracket
4 // rack_*: the Tortec rack
5 // adapt_*: the adapter, ie this file
9 // strength factor, set to 1 for real prints
13 brk_recess_actual = 5.20;
15 rack_rail_dia = 10.40 + 0.50;
16 rack_width_inner = 115.86 + 1.0; // between insides of rails
18 rear_elevation_nominal = 10.04; // top of rack to bottom of bracket
19 rear_to_front_distance = 230;
25 strap_barrel_dia = 14;
29 brk_block_z = 14.55 - 0.75;
31 brk_bolt_dia = 4.0 + 0.5;
32 brk_nearbolt_recess_dia = 8.86 + 1.5;
33 brk_nearbolt_recess_depth = 1.09 + 0.25;
35 brk_bolt_eff_len = 11.78 - 1.0; // inside of recess, to end of bolt
36 brk_bolt_len_slop = 2.0;;
37 brk_bolt_nut_th = 3.89;
38 brk_bolt_nut_across_flats = 7.86 + 0.50;
40 brk_overall_w = 90.07;
44 main_sz_y = $strf * 20;
45 grasp_sz = $strf * 12;
46 beside_strap_sz = $strf * 8;
53 main_sz_z = beside_strap_sz*2 + strap_w;
55 brk_bottom_y = -brk_recess_actual;
56 adapt_main_top_y = brk_bottom_y + general_gap_y;
59 rack_rail_x = -(rack_width_inner/2 + rack_rail_dia/2);
60 rack_rail_outer_x = -(rack_width_inner/2 + rack_rail_dia);
62 grasp_large_r = (rack_rail_dia + grasp_sz)/2;
63 grasp_large_x = rack_rail_outer_x + grasp_large_r;
65 block_x = grasp_large_x + grasp_large_r/2;
66 block_y_min = adapt_main_top_y - main_sz_y;
68 strap_barrel_x = rack_width_inner/2 + strap_barrel_dia/2;
70 rack_shear_ratio = rear_elevation_nominal / rear_to_front_distance;
72 brk_bolt_nut_top_y = -brk_nearbolt_recess_depth
73 - brk_bolt_eff_len + brk_bolt_nut_th + brk_bolt_len_slop;
75 brk_bolt_nut_r = brk_bolt_nut_across_flats/2 / cos(360/12);
77 module GraspElevation(){
79 translate([ grasp_large_x, adapt_main_top_y - grasp_large_r ])
80 circle(grasp_large_r);
82 translate([ grasp_large_x, $rack_rail_y - rack_rail_dia/2 ])
83 circle(grasp_large_r);
85 translate([ grasp_large_x, $rack_rail_y + rack_rail_dia/2 ])
86 circle(grasp_large_r);
90 module BlockElevation(){
92 rectfromto([ +block_x, adapt_main_top_y ],
93 [ -block_x, block_y_min ]);
94 rectfromto([ -grasp_large_x, adapt_main_top_y ],
95 [ +grasp_large_x, adapt_main_top_y - 0.1 ]);
100 linextr(0, main_sz_z)
104 s = rack_shear_ratio;
105 multmatrix([ [ 1, 0, 0, 0 ],
112 module GraspFixingElevation(){
115 mirror([1,0]) GraspElevation();
116 translate([ strap_barrel_x, $strap_barrel_y ])
117 circle(strap_barrel_dia/2 + strap_guide_sz);
120 rectfromto([0, $rack_rail_y],
121 [rack_width_inner, 50]);
123 translate([ rack_rail_x, $rack_rail_y ])
124 circle(r = rack_width_inner/2 - rack_rail_x);
126 [ rack_width_inner/2, 0 ],
127 $rail_fixing_fit_corner,
128 $rail_fixing_fit_corner + [-1,-1] * fit_slope_len,
129 [ -block_x, block_y_min ],
130 [ 0, block_y_min ]]);
136 module StrapBarrelElevation(){
137 translate([ strap_barrel_x, $strap_barrel_y ])
138 circle(strap_barrel_dia/2);
141 // Bracket support block, goes up inside bracket
142 // Z origin is bolt hole
144 linextr( -brk_block_z/2,
146 rectfromto([ -brk_block_xw/2, adapt_main_top_y - 0.1 ],
147 [ +brk_block_xw/2, 0 ]);
151 // Z origin is bolt hole
153 linextr_y_xz( -100, 10 )
154 circle(brk_bolt_dia/2);
156 linextr_y_xz( -brk_nearbolt_recess_depth, 10)
157 circle(brk_nearbolt_recess_dia/2);
159 linextr_y_xz( -100, brk_bolt_nut_top_y ) {
160 circle( r= brk_bolt_nut_r, $fn = 6 );
161 translate([ 0, brk_bolt_nut_across_flats/2 ])
162 circle( r=brk_bolt_nut_r/2, $fn = 4);
168 $rack_rail_y = brk_bottom_y - $elevation_nominal
169 - general_gap_y - rack_rail_dia/2;
171 $strap_barrel_y = $rack_rail_y + rack_rail_dia/2 + strap_barrel_dia/2;
173 $rail_fixing_fit_corner = [
175 $rack_rail_y - rack_rail_dia/2
183 RackShear() MainExtrude(){
184 StrapBarrelElevation();
186 translate([ 0,0, brk_block_z/2]) {
195 RackShear() MainExtrude(){
196 GraspFixingElevation();
200 translate([0,0, main_sz_z/2]) linextr(-strap_w/2, +strap_w/2) {
201 translate([ rack_width_inner/2 - strap_th, 0 ])
202 rectfromto([ 0, -50 ], [ 50, 50 ]);
207 RackShear() linextr(-10, main_sz_z+10) {
210 translate([ rack_rail_x, $rack_rail_y ]){
212 for (dx = [-rack_rail_dia, 0])
214 circle(r= rack_rail_dia/2);
221 translate([ 0,0, brk_block_z/2]) BoltHole();
225 module Front(){ ////toplevel
226 Principal($elevation_nominal=0);
229 module Rear(){ ////toplevel
230 Principal($elevation_nominal=rear_elevation_nominal);
233 module Demo(){ ////toplevel
239 translate([ 0, -2, -4 ])
240 square(center=true, [ brk_overall_w, 1 ]);