SpHEAR/TinySpHEAR_mount_pcb.scad

//
// *SpHEAR Project (Spherical Harmonics Ears), 
//
// Mount for four interface printed circuit boards
// 
// 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/

include <TinySpHEAR_common.scad>;

// size of printed circuit board
pcb_length = 85.090;
// measured = 16.26 (fit = 0.25)
pcb_width = 16.51;
// measured = 1.33 (fit = 0.28)
pcb_thickness = 1.61;

// we leave 12mm of the pcb exposed on the bottom of the body so that we
// can solder the wires that connect the microphone with the
// preamplifier, same at the top of the pcb to solder the wires
// to the capsules
pcb_low_exp = 12.0;
pcb_hi_exp = 8.0;

// diameter of four conductor cable
cable_diam = 9.5;

// lip that mounts flares into main body box
mount_lip = 6.0;

// main body corner radius
mount_corner = 10.0;

// capsule array mount, height of flare and stalk
flare_height = 50;
stalk_height = 40;

// add to length and width of pcb
pcb_fit = 0.25 / 2;

// add to thickness of pcb
pcb_tfit = 0.3;

// lip fit for flares (fit = 0.25)
// tried with 0.30 and seems to be fine
lip_fit = 0.30 / 2;

// wall thickness
wall = 1.0;

// back and front clearance of pcb (components and leads)
// pcb_front = 10.2;
pcb_front = 12.5;
pcb_back = 2.0;

// calculated minimum "radius" of microphone box
box_radius = pcb_front + (pcb_thickness + pcb_tfit) + pcb_back + 2 * wall;

// the printed circuit board

module pcb(length, width, thick) {
    translate([-width/2, 0, 0]) {
        cube([width, thick, length]);
    }
}

// the printed circuit board plus space in the front and back for components

module pcb_clear(length, width, thick, slot_depth, front, back) {
    translate([0, - (thick + front)]) {
        pcb(length, width, thick);
        // clear space in the front
        translate([- (width/2 - slot_depth), thick, 0]) {
            cube([width - 2 * slot_depth, front, length]);
        }
        // clear space in the back
        translate([- (width/2 - slot_depth), - back, 0]) {
            cube([width - 2 * slot_depth, back, length]);
        }    
    }
}

// all four printed circuit boards

module tetra_pcb_clear(length, width, thick, slot_depth, front, back) {
    for (rot = [0, 90, 180, 270]) {
        rotate([0, 0, rot]) {
            pcb_clear(pcb_length + 2*pcb_fit, pcb_width + 2*pcb_fit, pcb_thickness + pcb_tfit, slot_depth, front, back);
        }
    }
}

// create a box with rounded corners

module tetra_mount_box(height, radius, corner) {
    rd = radius - corner;
    minkowski() {
        translate([-rd, -rd, 0]) {
            cube([rd * 2, rd * 2, height / 2]);
        }
        cylinder(r = corner, h = height / 2, $fn = facets);
    }
}

module tetra_mount_box_relative(height, ref_radius, ref_corner, radius_inc) {
    corner = (ref_radius + radius_inc) * (ref_radius - ref_corner) / ref_radius;
    tetra_mount_box(height, ref_radius + radius_inc, corner);
}

// the main body of the microphone mount

module tetra_mount_body(height, radius, corner, lower_lip, upper_lip, clear) {
    difference() {
        tetra_mount_box(height, radius, corner);
        union() {
            // hollow out the inside with slots for pcbs
            tetra_pcb_clear(pcb_length, pcb_width, pcb_thickness, 1.0, pcb_front, pcb_back);
            // trim square angles
            cylinder(r = pcb_front, h = height, $fn = facets);
            // remove slots from inside body
            slot_len = 15;
            translate([0, 0, slot_len]) {
                hull() {
                    tetra_mount_box_relative(height - (3 * slot_len), radius, corner, - (2 * wall));
                    translate([0, 0, height - (2 * slot_len) + height / 3]) {
                        cylinder(r = radius / 3, h = 1, $fn = facets);
                    }
                }
            }
            // upper lip for flare to microphone
            translate([0, 0, height - upper_lip]) {
                difference() {
                    tetra_mount_box(upper_lip, radius, corner);
                    tetra_mount_box_relative(upper_lip, radius, corner, -(wall + lip_fit));
                }
            }
            // lower lip for flare to cable
            translate([0, 0, 0]) {
                difference() {
                    tetra_mount_box(lower_lip, radius, corner);
                    tetra_mount_box(lower_lip, radius, corner, -(wall + lip_fit));
                }
            }
        }
    }
    // external slot for microphone holder
    if (0) {
        mount_slot_len = 30;
        mount_slot_stem = 4;
        mount_slot_width = 2;
        mount_slot_radius = 2;
        translate([-(radius + mount_slot_stem), -(mount_slot_width/2), 0]) {
            cube([mount_slot_stem, mount_slot_width, mount_slot_len]);
        }
        translate([-(radius + mount_slot_stem), 0, 0]) {
            cylinder(r = mount_slot_radius, h = mount_slot_len, $fn = facets);
        }
    }
    // add parts for clearance check
    if (clear == 1) {
        // electrolytic capacitors
        cap_diam = 10.2;
        for (rot = [0, 180, 270]) {
            rotate([0, 0, rot]) {
                translate([-pcb_front + cap_diam/2, 0, 0]) {
                    cylinder(r = (cap_diam/2), h = 20, $fn = facets);
                }
            }
        }
        // 12.3 x 10.53 caps
        cap_h = 12.3;
        cap_w = 10.53/2;
        for (rot = [0, 180, 270]) {
            rotate([0, 0, rot]) {
                translate([-pcb_front + cap_h, -cap_w/2 - 2.5, 0]) {
                    cube([cap_h, cap_w, 20]);
                }
            }
        }
    }
}

// flares from the body to the microphone stalk and cable

module tetra_mount_flare(height, lip, transition, bot_radius, bot_corner, top_radius, stalk_height) {
    // bottom rounded box
    difference() {
        tetra_mount_box(height, bot_radius, bot_corner);
        tetra_mount_box_relative(height, bot_radius, bot_corner, -(2 * wall));
        // flange to mount on body
        tetra_mount_box_relative(lip + 1.0, bot_radius, bot_corner, - wall);
    }
    // flare to round section
    translate([0, 0, height]) {
        difference() {
            hull() {
                tetra_mount_box(1, bot_radius, bot_corner);
                translate([0, 0, transition]) {
                    cylinder(r = top_radius, h = 1, $fn = facets);
                }
            }
            hull() {
                tetra_mount_box_relative(1, bot_radius, bot_corner, - 2 * wall);
                translate([0, 0, transition]) {
                    cylinder(r = top_radius - wall, h = 1, $fn = facets);
                }
            }
        }
    }
    // cylindrical stalk
    translate([0, 0, height + transition]) {
        difference() {
            cylinder(r = top_radius, h = stalk_height, $fn = facets);
            cylinder(r = top_radius - wall, h = stalk_height, $fn = facets);
        }
    }
}

// top conical section that plugs into capsule array

module tetra_capsule_array_mount(angles) {
    difference() {
        translate([0, 0, 0]) {
            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);
                }
            }
        }
        // indentations that match the two lower capsule holders
        // add ridge height adjustment
        translate([0, 0, mount_top_height + (mic_radius - capsule_height) + capsule_height * sin(elev_angle)]) {
            capsule(angles[0], -elev_angle, [], 0, 1, 0.1, 3, 1);
            capsule(angles[1], -elev_angle, [], 0, 1, 0.1, 3, 1);
        }
    }
}

// internal ring of shock mount

module tetra_shock_mount_body_ring(height, radius, corner, rinc, lip) {
    slot_sep = radius * 2 / 2.7;
    slot_w = 6;
    slot_o = height / 3;
    // base ring
    *difference() {
        tetra_mount_box_relative(slot_o, radius + rinc, corner, 3 * wall);
        tetra_mount_box(slot_o, radius + rinc, corner);
    }
    // upper ring with slots for rubber bands
    difference() {
        tetra_mount_box_relative(height, radius + rinc, corner, 4 * wall);
        tetra_mount_box_relative(height, radius + rinc, corner, 2 * wall);
        for (rot = [0, 90, 180, 270]) {
            rotate([0, 0, rot]) {
                for (xo = [1, -1] * slot_sep) {
                    translate([-slot_w / 2 + xo, radius + rinc, slot_o]) {
                        // slots for rubber bands
                        cube([slot_w, 10, slot_o]);
                        translate([slot_w / 3, 0, 0]) {
                            cube([slot_w / 3, 10, 10]);
                        }
                    }
                }
            }
        }
    }    
    for (rot = [0, 90, 180, 270]) {
        rotate([0, 0, rot]) {
            // slots for connecting the upper and lower rings
            translate([radius + rinc + 2 * wall, -(slot_sep + slot_w/3)/2, 0]) {
                difference() {
                    cube([5, slot_sep + slot_w/3, height]);
                    translate([0, wall, 0]) {
                        cube([4, slot_sep + slot_w/3 - 2 * wall, 4]);
                    }
                }
            }
            // lip to support microphone on lower ring only
            if (lip == 1) {
                lip_w = 10;
                translate([radius + rinc + 2 * wall, -lip_w/2, height]) {
                    rotate([90, 90, 180]) {
                        linear_extrude(height = lip_w) {
                            polygon([[0, 0], [0, 4], [1, 4], [height * 2/3, 0]]);
                        }
                    }
                }
            }
        }
    }    
}

module tetra_shock_mount_main_ring(height, radius, corner, rinc, lip) {
    difference() {
        tetra_mount_box_relative(6, box_radius, mount_corner, rinc);
        tetra_mount_box_relative(6, box_radius, mount_corner, rinc - 4 * wall);
    }
    for (rot = [0, 90, 180, 270]) {
        rotate([0, 0, rot]) {
            translate([box_radius + rinc + 4 * wall, -7.5, 0]) {
                cube([4, 15, 6]);
            }
            translate([box_radius + rinc, -2, 0]) {
                cube([7, 4, 6]);
            }
        }
    }
}

// main body of microphone mount
//
*translate([0, 0, -(pcb_length - pcb_low_exp - pcb_hi_exp + 10)]) {
    tetra_mount_body(pcb_length - pcb_low_exp - pcb_hi_exp, box_radius + wall, mount_corner, mount_lip, mount_lip, 0);
}

// flare to microphone stalk
//

//translate([0, 0, pcb_length - pcb_low_exp - pcb_hi_exp + 10]) {
*translate([0, 0, 0]) {
    tetra_mount_flare(10 + pcb_hi_exp, mount_lip, flare_height, box_radius + wall,  mount_corner, 
                    mount_radius + wall, stalk_height);
    translate([0, 0, 10 + pcb_hi_exp + flare_height + stalk_height]) {
        tetra_capsule_array_mount([-45, 135]);
    }
}

// flare to microphone cable
//

//translate([0, 0, -(10 + pcb_length - pcb_low_exp - pcb_hi_exp + 10)]) {
translate([0, 0, -14]) {
    rotate([0, 180, 0]) {
        tetra_mount_flare(10 + pcb_low_exp, mount_lip, 20, box_radius + wall, mount_corner, cable_diam / 2 + wall, 10);
    }
}

// shock mount
//

ring_sep = 30;
ring_height = 6;
band_angle = 40;
main_radius_inc = (ring_sep / 2) / tan(band_angle);

translate([0, 0, -3]) {
    //rotate([0, 180, 0]) {
        tetra_shock_mount_body_ring(10, box_radius, mount_corner, 0.5, 0);
        rotate([0, 180, 0]) {
            translate([0, 0, ring_sep]) {
                tetra_shock_mount_body_ring(10, box_radius, mount_corner, 0.5, 1);
            }
        }
    //}
}

translate([0, 0, - ring_sep / 2 - 5]) {
        tetra_shock_mount_main_ring(10, box_radius, mount_corner, main_radius_inc, 0);
}

// first try at a ccrma logo
//
*rotate([90, 0, 0]) {
    translate([0, 10, box_radius + 1.5]) {
        scale([0.03, 0.03, 0.02]) {
            surface(file = "ccrma-black.png", center = true, invert = true);
        }
    }
}

// the microphone itself
rendermic = 1;

*translate([0, 0, 2.8 + pcb_hi_exp + flare_height + stalk_height + 30]) {
    // all four capsules
    capsule(45, elev_angle, leg_angles_top, 60, 0, 0.0, 0.0, 0);
    capsule(-135, elev_angle, leg_angles_top, 60, 0, 0.0, 0.0, 0);
    capsule(-45, -elev_angle, leg_angles_bot, 0, 1, 0.0, 0.0, 0);
    capsule(135, -elev_angle, leg_angles_bot, 0, 1, 0.0, 0.0, 0);
    // the mount
    *mount([-45, 135], mount_wall, mic_mount_wall, mic_mount_height + mount_top_height + mount_height + capsule_bottom);
}