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 = 39.65; // 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 * 18;
50 grasp_thin_sz = $strf * 0.5;
51 beside_strap_sz = $strf * 8;
58 main_sz_z = beside_strap_sz*2 + strap_w;
59 main_sz_x_fam = main_sz_y;
61 brk_bottom_y = -brk_recess_actual;
62 adapt_main_top_y = brk_bottom_y + general_gap_y;
65 rack_rail_x = -(rack_width_inner/2 + rack_rail_dia/2);
66 rack_rail_outer_x = -(rack_width_inner/2 + rack_rail_dia);
68 grasp_large_r = (rack_rail_dia + grasp_sz)/2;
69 grasp_small_r = (rack_rail_dia + grasp_thin_sz)/2;
70 grasp_large_x = rack_rail_outer_x + grasp_large_r;
71 grasp_small_x = rack_rail_outer_x + grasp_small_r;
73 block_x = grasp_large_x + grasp_large_r;
74 block_y_min = adapt_main_top_y - main_sz_y;
76 strap_barrel_x = rack_width_inner/2 + strap_barrel_dia/2;
78 rack_shear_ratio = -rear_elevation_nominal / rear_to_front_distance;
80 brk_bolt_nut_top_y = -brk_nearbolt_recess_depth
81 - brk_bolt_eff_len + brk_bolt_nut_th + brk_bolt_len_slop;
83 brk_bolt_nut_r = brk_bolt_nut_across_flats/2 / cos(360/12);
85 module GraspElevation(){
87 translate([ grasp_large_x, adapt_main_top_y - grasp_large_r ])
88 circle(grasp_large_r);
90 translate([ grasp_small_x, $rack_rail_y - rack_rail_dia/2 ])
91 circle(grasp_small_r);
93 translate([ rack_rail_x + grasp_large_r/2,
94 $rack_rail_y - rack_rail_dia/2 ])
95 circle(grasp_small_r);
97 translate([ grasp_large_x, $rack_rail_y + rack_rail_dia/2 ])
98 circle(grasp_large_r);
100 translate([ grasp_large_x + grasp_large_r/2,
101 $rack_rail_y + rack_rail_dia/2 ])
102 circle(grasp_large_r);
106 module BlockElevation(){
108 rectfromto([ +block_x, adapt_main_top_y ],
109 [ -block_x, block_y_min ]);
110 rectfromto([ -grasp_large_x, adapt_main_top_y ],
111 [ +grasp_large_x, adapt_main_top_y - 0.1 ]);
114 rectfromto([ +block_x, adapt_main_top_y ],
115 [ -block_x, block_y_min ]);
116 rectfromto([ grasp_large_x, block_y_min ],
117 [ 0, block_y_min + 0.1 ]);
121 module MainExtrude(){
122 linextr(0, main_sz_z)
126 s = rack_shear_ratio;
127 multmatrix([ [ 1, 0, 0, 0 ],
134 module GraspFixingElevation(){
141 translate([ -block_x, block_y_min ] + [0,0.1]*1 )
144 translate([ strap_barrel_x, $strap_barrel_y ])
145 circle(strap_barrel_dia/2 + strap_guide_sz);
148 rectfromto([0, $rack_rail_y],
149 [rack_width_inner, 50]);
151 translate([ rack_rail_x, $rack_rail_y ])
152 circle(r = rack_width_inner/2 - rack_rail_x);
153 polygon([ [ -block_x-0.1, 0 ],
154 [ rack_width_inner/2, 0 ],
155 $rail_fixing_fit_corner,
156 $rail_fixing_fit_corner + [-1,-1] * fit_slope_len,
157 [ -grasp_large_x - grasp_large_r*2, block_y_min ],
158 [ -block_x-0.1, block_y_min ]]);
164 module StrapBarrelElevation(){
165 translate([ strap_barrel_x, $strap_barrel_y ])
166 circle(strap_barrel_dia/2);
169 // Bracket support block, goes up inside bracket
170 // Z origin is bolt hole
172 linextr( -brk_block_z/2,
174 rectfromto([ -brk_block_xw/2, adapt_main_top_y - 0.1 ],
175 [ +brk_block_xw/2, 0 ]);
179 // Z origin is bolt hole
181 linextr_y_xz( -100, 10 )
182 circle(brk_bolt_dia/2);
184 linextr_y_xz( -brk_nearbolt_recess_depth, 10)
185 circle(brk_nearbolt_recess_dia/2);
187 linextr_y_xz( -100, brk_bolt_nut_top_y ) {
188 circle( r= brk_bolt_nut_r, $fn = 6 );
189 translate([ 0, brk_bolt_nut_across_flats/2 ])
190 circle( r=brk_bolt_nut_r/2, $fn = 4);
194 module AsForeAftMaint(){
195 if ($foreaftmaint_dz) {
202 $rack_rail_y = brk_bottom_y - $elevation_nominal
203 - general_gap_y - rack_rail_dia/2;
205 $strap_barrel_y = $rack_rail_y + rack_rail_dia/2 + strap_barrel_dia/2;
207 $rail_fixing_fit_corner = [
209 $rack_rail_y - rack_rail_dia/2
212 $foreaftmaint_rail_z = brk_block_z/2 + $foreaftmaint_dz;
213 $foreaftmaint_rail_y = $rack_rail_y
214 + $foreaftmaint_rail_z * rack_shear_ratio;
221 RackShear() MainExtrude(){
222 StrapBarrelElevation();
224 translate([ 0,0, brk_block_z/2]) {
233 RackShear() MainExtrude(){
234 GraspFixingElevation();
238 translate([0,0, main_sz_z/2]) linextr(-strap_w/2, +strap_w/2) {
239 translate([ rack_width_inner/2 - strap_th, 0 ])
240 rectfromto([ 0, -50 ], [ 50, 50 ]);
244 RackShear() AsForeAftMaint(){
245 linextr_x_yz(-main_sz_x_fam/2,
250 rectfromto([ -$foreaftmaint_rail_z, adapt_main_top_y ],
253 ybot = $foreaftmaint_rail_y - rack_rail_dia/2 + grasp_large_r
254 - fit_slope_len * 0.5;
257 adapt_main_top_y - grasp_large_r
259 for (dx= [-1,+1] * rack_rail_dia/2)
260 translate([ -$foreaftmaint_rail_z + dx, y ])
261 circle(r= grasp_large_r);
264 translate([0, adapt_main_top_y])
265 rectfromto([-500, 0], [500, 500]);
271 RackShear() linextr(-10, main_sz_z+10) {
274 translate([ rack_rail_x, $rack_rail_y ]){
276 for (dx = [-rack_rail_dia, 0])
278 circle(r= rack_rail_dia/2);
285 // Distance from bolt hole, in backwards direction
286 RackShear() AsForeAftMaint(){
287 cr = rack_rail_dia/2 + foreaftmaint_r_slop;
288 translate([ 0, $foreaftmaint_rail_y, $foreaftmaint_rail_z ])
289 linextr_x_yz(+rack_rail_x,
298 for (dd=[[0,0], [-1,-1], [-1,+1]]) {
300 [-1, 0] * (rack_rail_dia - fit_slope_len)
309 translate([ 0,0, brk_block_z/2]) BoltHole();
313 module Front(){ ////toplevel
314 // xxx elevation is wrong
315 Principal($elevation_nominal=0, $foreaftmaint_dz=0);
318 module Rear(){ ////toplevel
319 Principal($elevation_nominal=rear_elevation_nominal,
320 $foreaftmaint_dz= rear_to_cross_rail);
328 translate([ 0, -2, -4 ])
329 square(center=true, [ brk_overall_w, 1 ]);
334 module FrontDemo(){ ////toplevel
337 module RearDemo(){ ////toplevel