SpHEAR/TinySpHEAR_common.scad

//
// Spherical Harmonics Ear Project (*SpHEAR)
//
// TinySpHEAR, First Order (B-format) Ambisonics Microphone
// Common Modules and Variables
//
// Copyright 2015-2016, 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/

// https://en.wikipedia.org/wiki/Tetrahedron
// angle of capsule to vertical axis = atan(sqrt(2)) = 54.7356103172

////
//// default model parameters
////

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

// distance between the face of a capsule and the center of array
mic_radius = 9.6;

// dimensions of the capsule holder connection legs
// a width of 4mm is too thin, 5mm prints better
leg_width = 5;
leg_thick = 1.75;

// wall thickness of the capsule holder
wall = 1;

// width of the ridge that connects to the mount
ridge_width = 2.0;
ridge_slot_width = 2.0;
// depth of the connector mount ridge
ridge_depth = 3.0;
// add to the thickness of ridges
ridge_wfit = 0.1;
ridge_hfit = 3;

// microphone mount
//
mount_radius = 3.5;
mount_wall = 0.75;

// height and eccentricity of top connector
mount_top_height = 15.0;
mount_top_eccentricity = 1.3;

// height of mount
mount_height = 40;

// microphone stand mount
//
// diameter of existing shielded wires (x 4)
mic_wire_diam = 1.5;
mic_wire_hole_radius = 3.0;
mic_wire_hole_offset = 5;

// standard microphone stand
// measured diameter = 13.5, inside diameter of sleeve = 13.79 (
mic_mount_radius = 13.50 / 2;
// add this to inside diameter
mic_mount_fit = 0.2;
mic_mount_slot_height = 11.5;
mic_mount_slot_width = 4.25;
mic_mount_slot_radius = 6.25  / 2;
mic_mount_wall = 1.5;
mic_mount_height = 35.0 + mic_wire_hole_offset + mic_wire_hole_radius + 2 * mic_mount_wall;

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

// what type of connection to use between capsule holders:
// 0 -> original cylindrical angled legs
// 1 -> interlocking horizontal legs
// 2 -> interlocking vertical legs
connect = 1;

// how many mount ridges to create
// 0 -> no ridges
// 1 -> 1 ridge
// 2 -> 2 ridges
ridges = 1;

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

// elevation angle for the capsule holders (fixed for this microphone)
elev_angle = atan(sqrt(1/2));

// angles of the connection legs and adjacent capsule holders
leg_angles_top = 
    [
        [-120, elev_angle], 
        [0, elev_angle],
        [120, elev_angle]
    ];

leg_angles_bot = 
    [
        [-120, elev_angle], 
        [120, elev_angle]
    ];

// adjustment for the inner radius of the capsule holder
//   measured inside diameter of a trial print was around 7.5 to 8.2 
//   instead of 10, capsule diameter was 9.99)
// 0.1 -> 0.08: Ultimaker 2 + Extended plus APL (2016.06.17)
fudge = 0.08;

// adjustment for fit of slots in connection legs and mount
// 0.1: initial setting
// 0.1 ->0.15: Ultimaker 2 + Extended plus APL (2016.06.17)
fit = 0.15;

// number of facets for rendering cylinders
facets = 64;
// render capsule holders with better resolution
cfacets = 128;

// microphone structure 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_radius_capsule = capsule_sep_max;

// simple microphone mount, clips into standard microphone stand
//
// angles: angles for mount slots
// wall: thickness of cylinder wall
// stand_wall: thickness of stand mount wall
// separation: height of mount with respect of the microphone assembly (for display)

module ellipsoid(height, rad_bot, rad_top, eccentricity) {
    linear_extrude(height = height, scale = [eccentricity, rad_top / rad_bot]) {
        circle(r = rad_bot, $fn = facets); 
    }
}

module mount (angles, wall, stand_wall, separation) {
    translate([0, 0, -separation]) {
        difference() {
            union() {
                // conic section
                translate([0, 0, mic_mount_height + mount_height]) {
                    rotate([0, 0, 45]) {
                        difference() {
                            ellipsoid(mount_top_height, mount_radius + wall, mount_radius_capsule, mount_top_eccentricity);
                            ellipsoid(mount_top_height, mount_radius, mount_radius_capsule * 0.5, mount_top_eccentricity * 1.05);
                        }
                    }
                }
                // stalk
                translate([0, 0, mic_mount_height + mount_height * 2/3]) {
                    difference() {
                        cylinder(r = mount_radius + wall, h = mount_height / 3, $fn = facets);
                        // make the hole for the mount
                        cylinder(r = mount_radius, h = mount_height / 3, $fn = facets);
                    }
                }
                // transition to stand mount
                translate([0, 0, mic_mount_height]) {
                    difference() {
                        cylinder(r2 = mount_radius + wall, r1 = mic_mount_radius + mic_mount_fit + stand_wall, 
                                h = mount_height * 2 / 3, $fn = facets);
                        // make the hole for the mount
                        cylinder(r2 = mount_radius, r1 = mic_mount_radius + mic_mount_fit, 
                                h = mount_height * 2 / 3, $fn = facets);
                    }
                }
                // stand mount
                translate([0, 0, 0]) {
                    difference() {
                        union() {
                            // main mount cylinder
                            translate([0, 0, 0]) {
                                difference() {
                                    cylinder(r = mic_mount_radius + mic_mount_fit + stand_wall, h = mic_mount_height, $fn = facets);
                                    // make the hole for the mount (* 1.5 to cut the ridge as well)
                                    cylinder(r = mic_mount_radius + mic_mount_fit, h = mic_mount_height, $fn = facets);
                                }
                            }
                        }
                        // slot for fitting into microphone stand
                        translate([mic_mount_radius - stand_wall / 2, - mic_mount_slot_width / 2, 0]) {
                            cube([2 * stand_wall, mic_mount_slot_width, mic_mount_slot_height]);
                        }
                        // eyelet for microphone stand
                        translate([mic_mount_radius - stand_wall / 2, 0,  mic_mount_slot_height]) {
                            rotate([0, 90, 0]) {
                                cylinder(r = mic_mount_slot_radius, h = 2 * stand_wall, $fn = facets);
                            }
                        }
                        // hole for microphone wiring
                        translate([mic_mount_radius - stand_wall / 2, 0, mic_mount_height - mic_wire_hole_offset]) {
                            rotate([0, 90, 0]) {
                                cylinder(r = mic_wire_hole_radius, h = 2 * stand_wall, $fn = facets);
                            }
                        } 
                    }
                }
            }
            // indentations that match the two lower capsule holders
            translate([0, 0, mic_mount_height + mount_height + mount_top_height + 
                       (mic_radius - capsule_height) + capsule_height * cos(elev_angle)]) {
                rotate([0, (90 - elev_angle), angles[0]]) {
                    translate([0, 0, mic_radius - capsule_height]) {
                        capsule([], 0, 1, ridge_wfit, ridge_hfit, 1);
                    }
                }
                rotate([0, (90 - elev_angle), angles[1]]) {
                    translate([0, 0, mic_radius - capsule_height]) {
                        capsule([], 0, 1, ridge_wfit, ridge_hfit, 1);
                    }
                }
            }
        }
    }
}

// render a tetrahedral capsule array
//
module render_tetra_capsule_array(z_offset) {
    translate([0, 0, z_offset]) {
        // all four capsules
        rotate([0, (90 - elev_angle), 45]) {
            translate([0, 0, mic_radius - capsule_height]) {
                capsule(leg_angles_top, 60, 0, 0.0, 0.0, 0);
            }
        }
        rotate([0, (90 - elev_angle), -135]) {
            translate([0, 0, mic_radius - capsule_height]) {
                capsule(leg_angles_top, 60, 0, 0.0, 0.0, 0);
            }
        }
        rotate([0, (90 + elev_angle), -45]) {
            translate([0, 0, mic_radius - capsule_height]) {
                capsule(leg_angles_bot, 0, 1, 0.0, 0.0, 0);
            }
        }
        rotate([0, (90 + elev_angle), 135]) {
            translate([0, 0, mic_radius - capsule_height]) {
                capsule(leg_angles_bot, 0, 1, 0.0, 0.0, 0);
            }
        }
    }
}

// render individual capsules
//
module render_tetra_capsule_top() {
    capsule(leg_angles_top, 60, 0, 0.0, 0.0, 0);
}

module render_tetra_capsule_bot() {
    capsule(leg_angles_bot, 0, 1, 0.0, 0.0, 0);
}

// render simple microphone stand mount
//
module render_simple_stand_mount(z_offset) {
    translate([0, 0, z_offset]) {
        mount([-45, 135], mount_wall, mic_mount_wall, mic_mount_height + mount_top_height + mount_height + capsule_bottom);
    }
}