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;
19 // ^ top of rack to bottom of bracket, at rear bolt hold
20 rear_to_front_distance = 230;
21 rear_to_cross_rail = 19.65; // bolt centre to rail centre, rail to rear
27 strap_barrel_dia = 14;
31 brk_block_z = 14.55 - 0.75;
33 brk_bolt_dia = 4.0 + 0.5;
34 brk_nearbolt_recess_dia = 8.86 + 1.5;
35 brk_nearbolt_recess_depth = 1.09 + 0.25;
37 brk_bolt_eff_len = 11.78 - 1.0; // inside of recess, to end of bolt
38 brk_bolt_len_slop = 2.0;;
39 brk_bolt_nut_th = 3.89;
40 brk_bolt_nut_across_flats = 7.86 + 0.50;
42 brk_overall_w = 90.07;
46 foreaftmaint_r_slop = 0.75;
48 main_sz_y = $strf * 20;
50 beside_strap_sz = $strf * 8;
57 main_sz_z = beside_strap_sz*2 + strap_w;
58 main_sz_x_fam = main_sz_y;
60 brk_bottom_y = -brk_recess_actual;
61 adapt_main_top_y = brk_bottom_y + general_gap_y;
64 rack_rail_x = -(rack_width_inner/2 + rack_rail_dia/2);
65 rack_rail_outer_x = -(rack_width_inner/2 + rack_rail_dia);
67 grasp_large_r = (rack_rail_dia + grasp_sz)/2;
68 grasp_large_x = rack_rail_outer_x + grasp_large_r;
70 block_x = grasp_large_x + grasp_large_r;
71 block_y_min = adapt_main_top_y - main_sz_y;
73 strap_barrel_x = rack_width_inner/2 + strap_barrel_dia/2;
75 rack_shear_ratio = rear_elevation_nominal / rear_to_front_distance;
77 brk_bolt_nut_top_y = -brk_nearbolt_recess_depth
78 - brk_bolt_eff_len + brk_bolt_nut_th + brk_bolt_len_slop;
80 brk_bolt_nut_r = brk_bolt_nut_across_flats/2 / cos(360/12);
82 module GraspElevation(){
84 translate([ grasp_large_x, adapt_main_top_y - grasp_large_r ])
85 circle(grasp_large_r);
87 translate([ grasp_large_x, $rack_rail_y - rack_rail_dia/2 ])
88 circle(grasp_large_r);
90 translate([ grasp_large_x + grasp_large_r/2,
91 $rack_rail_y - rack_rail_dia/2 ])
92 circle(grasp_large_r);
94 translate([ grasp_large_x, $rack_rail_y + rack_rail_dia/2 ])
95 circle(grasp_large_r);
99 module BlockElevation(){
101 rectfromto([ +block_x, adapt_main_top_y ],
102 [ -block_x, block_y_min ]);
103 rectfromto([ -grasp_large_x, adapt_main_top_y ],
104 [ +grasp_large_x, adapt_main_top_y - 0.1 ]);
108 module MainExtrude(){
109 linextr(0, main_sz_z)
113 s = rack_shear_ratio;
114 multmatrix([ [ 1, 0, 0, 0 ],
121 module GraspFixingElevation(){
124 mirror([1,0]) GraspElevation();
125 translate([ strap_barrel_x, $strap_barrel_y ])
126 circle(strap_barrel_dia/2 + strap_guide_sz);
129 rectfromto([0, $rack_rail_y],
130 [rack_width_inner, 50]);
132 translate([ rack_rail_x, $rack_rail_y ])
133 circle(r = rack_width_inner/2 - rack_rail_x);
135 [ rack_width_inner/2, 0 ],
136 $rail_fixing_fit_corner,
137 $rail_fixing_fit_corner + [-1,-1] * fit_slope_len,
138 [ -grasp_large_x - grasp_large_r*2, block_y_min ],
139 [ 0, block_y_min ]]);
145 module StrapBarrelElevation(){
146 translate([ strap_barrel_x, $strap_barrel_y ])
147 circle(strap_barrel_dia/2);
150 // Bracket support block, goes up inside bracket
151 // Z origin is bolt hole
153 linextr( -brk_block_z/2,
155 rectfromto([ -brk_block_xw/2, adapt_main_top_y - 0.1 ],
156 [ +brk_block_xw/2, 0 ]);
160 // Z origin is bolt hole
162 linextr_y_xz( -100, 10 )
163 circle(brk_bolt_dia/2);
165 linextr_y_xz( -brk_nearbolt_recess_depth, 10)
166 circle(brk_nearbolt_recess_dia/2);
168 linextr_y_xz( -100, brk_bolt_nut_top_y ) {
169 circle( r= brk_bolt_nut_r, $fn = 6 );
170 translate([ 0, brk_bolt_nut_across_flats/2 ])
171 circle( r=brk_bolt_nut_r/2, $fn = 4);
175 module AsForeAftMaint(){
176 if ($foreaftmaint_dz) {
183 $rack_rail_y = brk_bottom_y - $elevation_nominal
184 - general_gap_y - rack_rail_dia/2;
186 $strap_barrel_y = $rack_rail_y + rack_rail_dia/2 + strap_barrel_dia/2;
188 $rail_fixing_fit_corner = [
190 $rack_rail_y - rack_rail_dia/2
193 $foreaftmaint_rail_z = brk_block_z/2 + $foreaftmaint_dz;
194 $foreaftmaint_rail_y = $rack_rail_y
195 + $foreaftmaint_rail_z * rack_shear_ratio;
202 RackShear() MainExtrude(){
203 StrapBarrelElevation();
205 translate([ 0,0, brk_block_z/2]) {
214 RackShear() MainExtrude(){
215 GraspFixingElevation();
219 translate([0,0, main_sz_z/2]) linextr(-strap_w/2, +strap_w/2) {
220 translate([ rack_width_inner/2 - strap_th, 0 ])
221 rectfromto([ 0, -50 ], [ 50, 50 ]);
226 linextr_x_yz(-main_sz_x_fam/2,
232 $foreaftmaint_rail_y - rack_rail_dia/2 + grasp_large_r,
233 adapt_main_top_y - grasp_large_r
235 for (dx= [-1,+1] * rack_rail_dia/2)
236 translate([ -$foreaftmaint_rail_z + dx, y ])
237 circle(r= grasp_large_r);
239 translate([0, adapt_main_top_y])
240 rectfromto([-500, 0], [500, 500]);
246 RackShear() linextr(-10, main_sz_z+10) {
249 translate([ rack_rail_x, $rack_rail_y ]){
251 for (dx = [-rack_rail_dia, 0])
253 circle(r= rack_rail_dia/2);
260 // Distance from bolt hole, in backwards direction
262 translate([ 0, $foreaftmaint_rail_y, $foreaftmaint_rail_z ])
263 linextr_x_yz(+rack_rail_x,
268 circle(r= rack_rail_dia/2 + foreaftmaint_r_slop);
274 translate([ 0,0, brk_block_z/2]) BoltHole();
278 module Front(){ ////toplevel
279 // xxx elevation is wrong
280 Principal($elevation_nominal=0, $foreaftmaint_dz=0);
283 module Rear(){ ////toplevel
284 Principal($elevation_nominal=rear_elevation_nominal,
285 $foreaftmaint_dz= rear_to_cross_rail);
288 module Demo(){ ////toplevel
294 translate([ 0, -2, -4 ])
295 square(center=true, [ brk_overall_w, 1 ]);