From ec2c99a68e67d185c5dabbf4cae28e41874e681b Mon Sep 17 00:00:00 2001 From: Antonio Ospite Date: Thu, 9 Aug 2018 18:54:46 +0200 Subject: [PATCH] Initial import --- OpenSCAD-Tetramag_spheres_holder.scad | 104 ++++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+) create mode 100644 OpenSCAD-Tetramag_spheres_holder.scad diff --git a/OpenSCAD-Tetramag_spheres_holder.scad b/OpenSCAD-Tetramag_spheres_holder.scad new file mode 100644 index 0000000..552db29 --- /dev/null +++ b/OpenSCAD-Tetramag_spheres_holder.scad @@ -0,0 +1,104 @@ +/* + * Draw a support to tie Tetramag spheres to a bike wheel. + * + * Copyright (C) 2018 Antonio Ospite + * SPDX-License-Identifier: GPL-3.0-or-later + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ + +/* + * Using a formula from: + * https://math.stackexchange.com/questions/12166/numbers-of-circles-around-a-circle + */ + +function calc_inner_radius(sphere_radius, number_of_spheres) = ( + let(ratio = sin(180 / number_of_spheres) / (1 - sin(180 / number_of_spheres))) + sphere_radius / ratio +); + +module draw_spheres(sphere_radius, number_of_spheres) { + if (sphere_radius <= 0) { + echo("Radius of outer spheres cannot be zero"); + } + + if (number_of_spheres < 3) { + echo("Number of outer spheres cannot be smaller than 3"); + } + + inner_radius = calc_inner_radius(sphere_radius, number_of_spheres); + + for (i = [0:number_of_spheres]) { + theta = i * 360 / number_of_spheres; + + /* + cx = sin(theta) * (inner_radius + sphere_radius); + cy = cos(theta) * (inner_radius + sphere_radius); + translate([cx, cy, 0]) { + sphere(sphere_radius, $fn=2); + } + */ + + /* A better version which also rotates the objects radially. */ + rotate ([0, 0, theta]) { + translate([0, inner_radius + sphere_radius, 0]) { + sphere(sphere_radius, $fn=40); + } + } + } +} + +module draw_cylinder(sphere_radius, number_of_spheres) { + radius = calc_inner_radius(sphere_radius, number_of_spheres) + sphere_radius / 2; + cylinder(sphere_radius * 2, r = radius, center=true, $fn=100); +} + +module draw_mounting_holes(hole_radius) { + /* 9 is the number of the bike spokes to attach the holder to. */ + mounting_holes = 9; + cube_size = 2; + cube_spacing = 2; + + for (i = [0:mounting_holes]) { + theta = i * 360 / mounting_holes; + rotate ([0, 0, theta]) { + translate([-cube_spacing, hole_radius + cube_size, 0]) { + cube([cube_size, cube_size, cube_size * 10], true); + }translate([cube_spacing, hole_radius + cube_size, 0]) { + cube([cube_size, cube_size, cube_size * 10], true); + } + } + } + +} + +module draw_holes(height, hole_radius) { + cylinder(height, r = hole_radius, center=true, $fn=100); + mounting_holes = 9; + cube_size = 2; + cube_spacing = 2; + + draw_mounting_holes(hole_radius); +} + +/* The actual parameters */ +sphere_radius = 2.5; +number_of_spheres = 38; +hole_radius = 47 / 2; // 47mm is the hole diameter + +difference() { + draw_cylinder(sphere_radius, number_of_spheres); + draw_spheres(sphere_radius, number_of_spheres); + draw_holes(sphere_radius * 3, hole_radius); +} -- 2.1.4