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 + 0.30;
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 rack cross rail (fam)
20 rear_to_front_distance = 230; // rack cross rail (fam) to very front end
21 rear_to_cross_rail = 35.05; // bolt centre to rail centre, rail to rear
22 rear_bolt_to_front_bolt = 155.4;
28 strap_barrel_dia = 14;
32 brk_block_z = 14.55 - 0.75;
34 brk_bolt_dia = 4.0 + 0.5;
35 brk_nearbolt_recess_dia = 8.86 + 1.5;
36 brk_nearbolt_recess_depth = 1.09 + 0.25;
38 brk_bolt_eff_len = 11.78 - 1.0; // inside of recess, to end of bolt
39 brk_bolt_len_slop = 2.0;;
40 brk_bolt_nut_th = 3.89;
41 brk_bolt_nut_across_flats = 7.86 + 0.50;
43 brk_overall_w = 90.07;
47 // "foreaftmaint" aka "fam" is the hook-like part that stops
48 // the adapter sliding forwards/backwards along the rails
49 foreaftmaint_r_slop = 0.75;
51 main_sz_y = $strf * 18;
53 grasp_thin_sz = $strf * 0.5;
54 beside_strap_sz = $strf * 8;
55 main_sz_core_z = $strf * 18;
57 // "length" in for-aft direction of interaction with rack rail
58 min_on_rail_sz_z = $strf * 25;
65 main_sz_rhs_z = max(min_on_rail_sz_z, beside_strap_sz*2 + strap_w);
66 main_sz_lhs_z = min_on_rail_sz_z;
68 main_sz_x_fam = main_sz_y;
70 brk_bottom_y = -brk_recess_actual;
71 adapt_main_top_y = brk_bottom_y - general_gap_y;
74 rack_rail_x = -(rack_width_inner/2 + rack_rail_dia/2);
75 rack_rail_outer_x = -(rack_width_inner/2 + rack_rail_dia);
77 grasp_large_r = (rack_rail_dia + grasp_sz)/2;
78 grasp_small_r = (rack_rail_dia + grasp_thin_sz)/2;
79 grasp_large_x = rack_rail_outer_x + grasp_large_r;
80 grasp_small_x = rack_rail_outer_x + grasp_small_r;
82 block_x = grasp_large_x + grasp_large_r;
83 block_y_min = adapt_main_top_y - main_sz_y;
85 strap_barrel_x = rack_width_inner/2 + strap_barrel_dia/2;
87 rack_shear_ratio = -rear_elevation_nominal / rear_to_front_distance;
89 brk_bolt_nut_top_y = -brk_nearbolt_recess_depth
90 - brk_bolt_eff_len + brk_bolt_nut_th + brk_bolt_len_slop;
92 brk_bolt_nut_r = brk_bolt_nut_across_flats/2 / cos(360/12);
94 function elevation_of_bolt_for(z) = rear_elevation_nominal
95 - (z - brk_block_z/2) * rack_shear_ratio;
97 function rack_rail_y_of_elevation(elevation_nominal) =
98 brk_bottom_y - elevation_nominal - general_gap_y - rack_rail_dia/2;
100 echo(rack_shear_ratio);
102 module GraspElevation(){
104 translate([ grasp_large_x, adapt_main_top_y - grasp_large_r ])
105 circle(grasp_large_r);
107 translate([ grasp_small_x, $rack_rail_y - rack_rail_dia/2 ])
108 circle(grasp_small_r);
110 translate([ rack_rail_x + grasp_large_r/2,
111 $rack_rail_y - rack_rail_dia/2 ])
112 circle(grasp_small_r);
114 translate([ grasp_large_x, $rack_rail_y + rack_rail_dia/2 ])
115 circle(grasp_large_r);
117 translate([ grasp_large_x + grasp_large_r/2,
118 $rack_rail_y + rack_rail_dia/2 ])
119 circle(grasp_large_r);
123 module BlockElevation(){
125 rectfromto([ +block_x, adapt_main_top_y ],
126 [ -block_x, block_y_min ]);
127 rectfromto([ -grasp_large_x, adapt_main_top_y ],
128 [ +grasp_large_x, adapt_main_top_y - 0.1 ]);
131 rectfromto([ +block_x, adapt_main_top_y ],
132 [ -block_x, block_y_min ]);
133 rectfromto([ grasp_large_x, block_y_min ],
134 [ 0, block_y_min + 0.1 ]);
138 module MainExtrude(z){
143 s = rack_shear_ratio;
144 multmatrix([ [ 1, 0, 0, 0 ],
151 module GraspFixingElevation(){
158 translate([ -block_x, block_y_min ] + [0,0.1]*1 )
161 translate([ strap_barrel_x, $strap_barrel_y ])
162 circle(strap_barrel_dia/2 + strap_guide_sz);
165 rectfromto([0, $rack_rail_y],
166 [rack_width_inner, 50]);
168 translate([ rack_rail_x, $rack_rail_y ])
169 circle(r = rack_width_inner/2 - rack_rail_x);
170 polygon([ [ -block_x-0.1, 0 ],
171 [ rack_width_inner/2, 0 ],
172 $rail_fixing_fit_corner,
173 $rail_fixing_fit_corner + [-1,-1] * fit_slope_len,
174 [ -grasp_large_x - grasp_large_r*2, block_y_min ],
175 [ -block_x-0.1 -2, block_y_min +2 ]]);
181 module StrapBarrelElevation(){
182 translate([ strap_barrel_x, $strap_barrel_y ])
183 circle(strap_barrel_dia/2);
186 // Bracket support block, goes up inside bracket
187 // Z origin is bolt hole
189 linextr( -brk_block_z/2,
191 rectfromto([ -brk_block_xw/2, adapt_main_top_y - 0.1 ],
192 [ +brk_block_xw/2, 0 ]);
196 // Z origin is bolt hole
198 linextr_y_xz( -100, 10 )
199 circle(brk_bolt_dia/2);
201 linextr_y_xz( -brk_nearbolt_recess_depth, 10)
202 circle(brk_nearbolt_recess_dia/2);
204 linextr_y_xz( -100, brk_bolt_nut_top_y ) {
205 circle( r= brk_bolt_nut_r, $fn = 6 );
206 translate([ 0, brk_bolt_nut_across_flats/2 ])
207 circle( r=brk_bolt_nut_r/2, $fn = 4);
212 if ($foreaftmaint_dz) {
219 linextr_x_yz(-main_sz_x_fam/2, +main_sz_x_fam/2)
225 $rack_rail_y = rack_rail_y_of_elevation($elevation_nominal);
227 $strap_barrel_y = $rack_rail_y + rack_rail_dia/2 + strap_barrel_dia/2;
229 $rail_fixing_fit_corner = [
231 $rack_rail_y - rack_rail_dia/2
234 $foreaftmaint_rail_z = brk_block_z/2 + $foreaftmaint_dz;
238 MainExtrude(main_sz_lhs_z){
241 RackShear() MainExtrude(main_sz_rhs_z){
242 StrapBarrelElevation();
244 translate([ 0,0, brk_block_z/2]) {
250 MainExtrude(main_sz_core_z){
254 MainExtrude(max(brk_block_z, main_sz_rhs_z)){
257 rectfromto([-block_x -5, adapt_main_top_y],
258 [-grasp_large_x, block_y_min]);
261 RackShear() MainExtrude(main_sz_rhs_z){
262 GraspFixingElevation();
266 translate([0,0, main_sz_rhs_z/2]) linextr(-strap_w/2, +strap_w/2) {
267 translate([ rack_width_inner/2 - strap_th, 0 ])
268 rectfromto([ 0, -50 ], [ 50, 50 ]);
275 rectfromto([ -$foreaftmaint_rail_z, adapt_main_top_y ],
279 ybot = $rack_rail_y - rack_rail_dia/2 + grasp_large_r
280 - fit_slope_len * 0.5;
283 adapt_main_top_y - grasp_large_r
285 for (dx= [-1,+1] * rack_rail_dia/2)
286 translate([ -$foreaftmaint_rail_z + dx, y ])
287 circle(r= grasp_large_r);
289 translate([0, adapt_main_top_y])
290 rectfromto([-500, 0], [500, 500]);
296 RackShear() linextr(-10, main_sz_lhs_z+main_sz_rhs_z) {
299 translate([ rack_rail_x, $rack_rail_y ]){
301 for (dx = [-rack_rail_dia, 0])
303 circle(r= rack_rail_dia/2);
311 // Distance from bolt hole, in backwards direction
312 cr = rack_rail_dia/2 + foreaftmaint_r_slop;
313 translate([ 0, $rack_rail_y, $foreaftmaint_rail_z ])
314 linextr_x_yz(+rack_rail_x,
323 for (dd=[[0,0], [-1,-1], [-1,+1]]) {
325 [-1, 0] * (rack_rail_dia - fit_slope_len)
334 translate([ 0,0, brk_block_z/2]) BoltHole();
338 module RackForDemo(){ ////toplevel
339 elevation = elevation_of_bolt_for(rear_to_cross_rail);
340 rack_rail_y = rack_rail_y_of_elevation(elevation);
342 rotate([-atan(rack_shear_ratio), 0,0])
343 translate([0, rack_rail_y, brk_block_z/2 + rack_rail_y*rack_shear_ratio]) {
344 for (m=[0]) mirror([m,0,0]) {
345 linextr(-50, 50 + rear_to_cross_rail)
346 translate([rack_rail_x, 0])
347 circle(r= rack_rail_dia/2);
349 translate([0,0, rear_to_cross_rail])
350 linextr_x_yz(rack_rail_x, -rack_rail_x)
351 circle(r= rack_rail_dia/2);
355 module Front(){ ////toplevel
356 // xxx elevation is wrong
357 Principal($elevation_nominal=
358 elevation_of_bolt_for(rear_to_cross_rail + rear_bolt_to_front_bolt),
359 $foreaftmaint_dz= 0);
362 module Rear(){ ////toplevel
363 Principal($elevation_nominal=
364 elevation_of_bolt_for(rear_to_cross_rail),
365 $foreaftmaint_dz= rear_to_cross_rail);
373 translate([ 0, -2, -4 ])
374 square(center=true, [ brk_overall_w, 1 ]);
379 module FrontDemo(){ ////toplevel
382 module RearDemo(){ ////toplevel
385 module RearRackDemo(){ ////toplevel
386 rotate([atan(rack_shear_ratio),0,0]) SomeDemo() {