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 = 12;
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;
42 main_sz_y = $strf * 20;
43 grasp_sz = $strf * 12;
44 beside_strap_sz = $strf * 8;
51 main_sz_z = beside_strap_sz*2 + strap_w;
53 brk_bottom_y = -brk_recess_actual;
54 adapt_main_top_y = brk_bottom_y + general_gap_y;
57 rack_rail_x = -(rack_width_inner/2 + rack_rail_dia/2);
58 rack_rail_outer_x = -(rack_width_inner/2 + rack_rail_dia);
60 grasp_large_r = (rack_rail_dia + grasp_sz)/2;
61 grasp_large_x = rack_rail_outer_x + grasp_large_r;
63 block_x = grasp_large_x + grasp_large_r/2;
64 block_y_min = adapt_main_top_y - main_sz_y;
66 strap_barrel_x = rack_width_inner/2 + strap_barrel_dia/2;
68 rack_shear_ratio = rear_elevation_nominal / rear_to_front_distance;
70 brk_bolt_nut_top_y = -brk_nearbolt_recess_depth
71 - brk_bolt_eff_len + brk_bolt_nut_th + brk_bolt_len_slop;
73 brk_bolt_nut_r = brk_bolt_nut_across_flats/2 / cos(360/12);
75 module GraspElevation(){
77 translate([ grasp_large_x, adapt_main_top_y - grasp_large_r ])
78 circle(grasp_large_r);
80 translate([ grasp_large_x, $rack_rail_y - rack_rail_dia/2 ])
81 circle(grasp_large_r);
83 translate([ grasp_large_x, $rack_rail_y + rack_rail_dia/2 ])
84 circle(grasp_large_r);
88 module BlockElevation(){
89 rectfromto([ +block_x, adapt_main_top_y ],
90 [ -block_x, block_y_min ]);
99 multmatrix([ [ 1, 0, 0, 0 ],
106 module GraspFixingElevation(){
109 mirror([1,0]) GraspElevation();
110 translate([ strap_barrel_x, $strap_barrel_y ])
111 circle(strap_barrel_dia/2 + strap_guide_sz);
114 rectfromto([0, $rack_rail_y],
115 [rack_width_inner, 50]);
117 translate([ rack_rail_x, $rack_rail_y ])
118 circle(r = rack_width_inner/2 - rack_rail_x);
120 [ rack_width_inner/2, 0 ],
121 [ rack_width_inner/2, $rack_rail_y - rack_rail_dia/2 ],
122 [ -block_x, block_y_min ],
123 [ 0, block_y_min ]]);
129 module StrapBarrelElevation(){
130 translate([ strap_barrel_x, $strap_barrel_y ])
131 circle(strap_barrel_dia/2);
134 // Bracket support block, goes up inside bracket
135 // Z origin is bolt hole
137 linextr( -brk_block_z/2,
139 rectfromto([ -brk_block_xw/2, adapt_main_top_y - 0.1 ],
140 [ +brk_block_xw/2, 0 ]);
144 // Z origin is bolt hole
146 linextr_y_xz( -100, 10 )
147 circle(brk_bolt_dia/2);
149 linextr_y_xz( -brk_nearbolt_recess_depth, 10)
150 circle(brk_nearbolt_recess_dia/2);
152 linextr_y_xz( -100, brk_bolt_nut_top_y ) {
153 circle( r= brk_bolt_nut_r, $fn = 6 );
154 translate([ 0, brk_bolt_nut_across_flats/2 ])
155 circle( r=brk_bolt_nut_r/2, $fn = 4);
161 $rack_rail_y = brk_bottom_y - $elevation_nominal
162 - general_gap_y - rack_rail_dia/2;
164 $strap_barrel_y = $rack_rail_y + rack_rail_dia/2 + strap_barrel_dia/2;
172 RackShear() MainExtrude(){
173 StrapBarrelElevation();
175 translate([ 0,0, brk_block_z/2]) BrkBlock();
178 RackShear() MainExtrude(){
179 GraspFixingElevation();
182 translate([0,0, main_sz_z/2]) linextr(-strap_w/2, +strap_w/2) {
183 translate([ rack_width_inner/2 - strap_th, 0 ])
184 rectfromto([ 0, -50 ], [ 50, 50 ]);
189 RackShear() linextr(-10, main_sz_z+10) {
192 translate([ rack_rail_x, $rack_rail_y ]){
194 for (dx = [-rack_rail_dia, 0])
196 circle(r= rack_rail_dia/2);
203 translate([ 0,0, brk_block_z/2]) BoltHole();
207 module Front(){ ////toplevel
208 Principal($elevation_nominal=0);
211 module Rear(){ ////toplevel
212 Principal($elevation_nominal=rear_elevation_nominal);
215 module Demo(){ ////toplevel
221 translate([ 0, -2, -4 ])
222 square(center=true, [ brk_overall_w, 1 ]);