SpHEAR/BigSpHEAR_20.scad

//
// BigSpHEAR (Big Spherical Harmonics Ear), 20 capsule spherical Ambisonics microphone
//
// Copyright 2015, Fernando Lopez-Lezcano, All Rights Reserved
// nando@ccrma.stanford.edu
//
//
//  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 <http://www.gnu.org/licenses/>.
//
//
// 3d Models released under the Creative Commons license as follows:
//   Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
// http://creativecommons.org/licenses/by-nc-sa/4.0/


////
//// model parameters

// dimensions of the EM182 electret microphone
capsule_radius = 5;
capsule_height = 4.5;

// distance between face of capsule and center of array
mic_radius = 25;

// dimensions of capsule holder connection legs
leg_width = 4;
leg_thick = 3;

// width of the ridge that connects to the mount
ridge_width = 2;
ridge_length = 2;

// wall thickness of capsule holder
wall = 1;

// dimensions of microphone holder
mount_radius = 4.5;

// height of mount
mount_height = 4;

//// end of model parameters
////
//// rendering control

// what to render:
// 0 -> ready to print
//   set = 0 -> one capsule, set = 1 -> a set of capsules
// 1 -> the whole microhone with four capsules
rendermic = 0;
renderset = 1;

// what type of connection to use between capsule holders:
// 0 -> original cylinder beams
// 1 -> interlocking beams (out)
// 2 -> interlocking beams (in)
connect = 1;

// adjustment for the radius of the capsule
//   measured inside diameter of a trial print was around 7.5 to 8.2 
//   instead of 10, capsule diameter was 9.99)
fudge = 0.15;

// adjustment for fit of slots in connection legs and mount
fit = 0.1;
slot_extra_depth = 1.0;

// number of facets for rendering cylinders
facets = 64;

//// end of rendering control
////

// https://en.wikipedia.org/wiki/Regular_dodecahedron
//
// cartesian coordinates of the vertices
//
//    (±1, ±1, ±1)
//    (0, ±1/φ, ±φ)
//    (±1/φ, ±φ, 0)
//    (±φ, 0, ±1/φ)
//
// where φ = 1 + √5/2 is the golden ratio (also written τ) ≈ 1.618

gold = (1 + sqrt(5)) / 2;
diedral = 2 * asin(sqrt(3) * (sqrt(5) - 1) / 6) / 2;

// first three elements are x,y,z coordinates, fourth element is twist of legs

vertices = 
    [
        [-1, -1, -1, diedral], 
        [-1, -1, 1, 60 - diedral], 
        [-1, 1, -1, - diedral], 
        [-1, 1, 1, - 60 + diedral], 
        [1, -1, -1, - diedral], 
        [1, -1, 1, - 60 + diedral], 
        [1, 1, -1, diedral], 
        [1, 1, 1, 60 - diedral], 

        [0, -1/gold, -gold, 0],
        [0, -1/gold, gold, 60],
        [0, 1/gold, -gold, 0],
        [0, 1/gold, gold, -60],
    
        [-1/gold, -gold, 0, - 60 / 2],
        [-1/gold, gold, 0, 60 / 2],
        [1/gold, -gold, 0, 60 / 2],
        [1/gold, gold, 0, -60 / 2],

        [-gold, 0, -1/gold, - 60], 
        [-gold, 0, 1/gold, 0], 
        [gold, 0, -1/gold, -60], 
        [gold, 0, 1/gold, 0]
    ];
    
// this needs to be fixed for this design (only works on the octathingy...)
elev_angle =  tetra_compat == 0 ? atan(1 / (2 * sqrt(sqrt(2))) * sqrt(2)) : atan(sqrt(1/2));

// microphone holder geometry
capsule_sep_min = (mic_radius - capsule_height) * cos(elev_angle) - (capsule_radius + wall) * sin(elev_angle);
capsule_sep_max = mic_radius * cos(elev_angle) - (capsule_radius + wall) * sin(elev_angle);
capsule_bottom = mic_radius * sin(elev_angle) + (capsule_radius + wall) * cos(elev_angle);
mount_slot_depth = ridge_length * sin(elev_angle);

////////
// microphone capsule holder

// azimuth: horizontal orientation of the capsule
// elevation: vertical orientation of the capsure
// mounts: vectors containing the angle of the mount and the angle to the adjacent capsule
// twist: rotate the whole capsule to match mounting legs

module capsule (azimuth, elevation, mounts, twist, ridge) {
	rotate([0, 0, azimuth]) {
		rotate([0, (90 - elevation), 0]) {
  			translate([0, 0, rendermic == 0 ? 0 : mic_radius - capsule_height]) {
				difference () {
					union () {
						// main capsule holder
						cylinder(r = capsule_radius + wall, h = capsule_height, $fn = facets);	
						// the mounting legs
						for (angles = mounts) {
							rotate([0, 0, angles[0] + twist]) {
								// connect with cylindrical beams, very pretty
                                leg_length = mic_radius * sin(angles[1]) - (capsule_radius + wall) * cos(angles[1]) + wall;
								if (connect == 0) {
									translate([capsule_radius - wall, 0, capsule_height - wall]) {
										rotate([0, 180 - (90 - angles[1]), 0]) {
											cylinder(d = leg_width, h = leg_length - 0.1, center = false, $fn = facets);
										}
									}
								}
								// connect with horizontal legs
								if (connect == 1) {
                                    leg_length = (mic_radius - capsule_height + leg_thick) * tan(angles[1]) - capsule_radius
                                                    + slot_extra_depth;
                                    slot_depth = leg_thick * cos(90 - 2 * angles[1]) + slot_extra_depth + fit;
                                    rest_length = leg_length - leg_thick * tan(angles[1]);
									translate([capsule_radius + leg_length + fudge, - leg_width / 3, 0]) {
										rotate([0, -90, 0]) {
											difference() {
                                                union() {
                                                    // leg
                                                    cube([leg_thick, leg_width, leg_length]);
                                                    // rest
                                                    translate([0, -leg_width / 3 - (fit / 2), 
                                                               leg_length - rest_length + slot_extra_depth]) {
                                                        cube([leg_thick, leg_width, rest_length]);
                                                    }
                                                }
												// cut slot in connector
                                                translate([0, leg_width / 3 - (fit / 2), 0]) {
                                                    cube([leg_thick, leg_width / 3 + fit, slot_depth]);
                                                }
                                                // make ramp in rest
                                                translate([-fit, 0, leg_length - rest_length + slot_extra_depth]) {
                                                    rotate([0, 2 * angles[1], 0]) {
                                                        translate([0, - leg_width / 3 - fit, 0]) {
                                                            cube([leg_thick, leg_width / 3 + fit, rest_length + 2 * fit]);
                                                        }
                                                    }
                                                }
											}
										}
									}
								}
								// connect with vertical legs
								if (connect == 2) {
                                    leg_length = (mic_radius * tan(angles[1]) - capsule_radius) * tan(90 - angles[1]); 
                                    slot_depth = leg_thick * (cos (90 - 2 * angles[1]) + tan(90 - 2 * angles[1])) + fit;
									translate([capsule_radius + fudge, - leg_width / 3, - leg_length + capsule_height]) {
										difference() {
											// thickness, width
											cube([leg_thick, leg_width, leg_length]);
											// cut slot in connector
											translate([0, leg_width / 3 - (fit / 2), 0]) {
												cube([leg_thick, leg_width / 3 + fit, slot_depth]);
											}
										}
									}
								}
							}
						}
						// add ridges for microphone mount
						if (ridge == 1) {
							rotate([0, 0, twist]) {
								translate([capsule_radius + fudge, - wall , 0]) {
									difference() {
										cube([ridge_length, ridge_width, capsule_height], center = false);
										//rotate([0, 90 - elev_angle, 0]) {
										//	cube([ridge_length, ridge_width, capsule_height], center = false);
										//}
									}
								}
							}
						}
					}
					// make the hole for the capsule
					translate ([0, 0, -2]) {
						cylinder(r = capsule_radius + fudge, h = capsule_height + 2, $fn = facets);
					}
					// remove any extra connecting beam material from the face of the holder
					if (connect == 0) {
						translate ([0, 0, capsule_height]) {
							cylinder(r = capsule_radius + wall * 2, h = 2, $fn = facets);
						}
					}
				}
			}
		}
	}
}

// microphone mount
//
// angles: angles for mount slots
// wall: thickness of cylinder wall
// separation: height of mount with respect of the microphone assembly

module mount (angles, wall, separation) {
	translate([0, 0, -(separation + 0.1)]) {
		difference() {
			union() {
				// grips for the capsule holder ridge
				for (rot = angles) {
					rotate([0, 0, rot]) {
						translate([-capsule_sep_max, -(ridge_width - fit / 2), -mount_height]) {
							cube([capsule_sep_max, ridge_width * 2 - fit, mount_height]);
                            rotate([0, -elev_angle, 0]) {
                                cube([capsule_sep_max, ridge_width * 2 - fit, mount_height * cos(elev_angle)]);
                            }
						}
					}
				}
				translate([0, 0, -mount_height]) {
					cylinder(r = mount_radius + wall, h = mount_height, $fn = facets);
				}
			}
			// make the hole for the mount (* 2 to cut the ridge as well)
			translate([0, 0, -mount_height]) {
				cylinder(r = mount_radius, h = mount_height * 2, $fn = facets);
			}
            // cut the outside of the sloped ridge
			translate([0, 0, -mount_height]) {
                difference() {
                    cylinder(r = capsule_sep_max + mount_height * 2, h = mount_height * 2, $fn = facets);
                    cylinder(r = capsule_sep_max, h = mount_height * 2, $fn = facets);
                }
			}
			// and cut a slot for the ridges in the wall of the cylinder
            for (rot = angles) {
                rotate([0, 0, rot]) {
                    translate([-capsule_sep_max * 2, -ridge_width + 4 * fit, -mount_slot_depth]) {
                        cube([capsule_sep_max * 2, ridge_width + 2 * fit, mount_height * 2]);
                    }
                }
			}
		}
	}
}

elev = atan(1/2);

echo("diedral angle ", diedral);

leg_angles = 
    [
        [-120, diedral], 
        [0, diedral],
        [120, diedral],
    ];

// render a complete microphone
if (rendermic == 1) {
    for (i = [0 : 1 : len(vertices) - 1]) {
        az = atan2(vertices[i][1], vertices[i][0]);
        el = 90 - acos(vertices[i][2] / norm([vertices[i][0], vertices[i][1], vertices[i][2]]));
        tw = vertices[i][3];
        echo(i, vertices[i], " az=", az, " el=", el);
        capsule(az, el, leg_angles, tw, 0);
    }
} else {
													    
    // print all the parts separately
    part_sep = capsule_radius * 4.2;
    if (renderset == 1) {
        if (connect == 1) {
            twist_all = 0;
            translate([0, 0, 0]) { capsule(0, 90, leg_angles, twist_all, 0); }
            translate([0, part_sep, 0]) { capsule(0, 90, leg_angles, twist_all, 0); }
            translate([part_sep, 0, 0]) { capsule(0, 90, leg_angles, twist_all, 0); }
            translate([part_sep, part_sep]) { capsule(0, 90, leg_angles, twist_all, 0); }
            translate([-part_sep, 0, 0]) { capsule(0, 90, leg_angles, twist_all, 0); }
            translate([-part_sep, part_sep]) { capsule(0, 90, leg_angles, twist_all, 0); }
            translate([-part_sep / 2, -part_sep * 2 / 3, 0]) { capsule(0, 90, leg_angles, twist_all, 0); }
            translate([part_sep / 2, -part_sep * 2 / 3, 0]) { capsule(0, 90, leg_angles, twist_all, 0); }
            // ridges to connect all parts
            translate([-part_sep + wall, part_sep / 2 - wall, 0]) {
                cube([part_sep * 2, wall, wall / 2]);
            }
            for (d = [-part_sep, 0, part_sep]) {
                translate([wall + d, capsule_radius, 0]) {
                    cube([wall, part_sep - capsule_radius * 2, wall / 2]);
                }
            }
            for (d = [-part_sep / 2, part_sep / 2]) {
                translate([wall + d, - part_sep * 2 / 3 + capsule_radius, 0]) {
                    cube([wall, part_sep / 2 + part_sep * 2 / 3 - capsule_radius, wall / 2]);
                }
            }
        }
    } else {
        // just a single capsule holder
        translate([0, 0, 0]) { capsule(0, 90, leg_angles, 0, 0); }
    }
}