8BitDo Micro Phone Clip

// Taco clip that holds an 8BitDo Micro on the lower part of a phone screen, for DS and other
// retro emulation in portrait. The clip wraps around the bottom edge of the phone: a plate on
// the screen, a PETG spring on the back. It fits phones from 6 to 12 mm thick (with case) and
// any width. The Micro sits in a tray that slides onto two dovetail rails on the plate.
// Two prints, no hardware. The USB-C port stays free through the bottom.

/* [Fit] */
// Room around the Micro in its tray, per side.
micro_fit = 0.4; // [0.2:0.1:1]
// Thickness of the Micro's body at its edge, without the buttons. Lower it if the Micro sits loose.
micro_thickness = 12; // [10:0.2:14]
// Thickness of the back spring. Thicker grips harder.
spring_thickness = 2; // [1.6:0.2:2.6]

/* [Preview] */
// Print: both parts laid out on the bed. Assembled: tray on the clip. On phone: with a phone and the Micro.
layout = "Print"; // [Print, Assembled, On phone]
// Phone thickness in the preview.
preview_phone_thickness = 11; // [6:0.5:12]

/* [Colour] */
// Display only, the STL carries no colour.
color_clip = "DimGray"; // [DimGray, Black, White, Silver, SteelBlue, FireBrick, Goldenrod]

/* [Hidden] */
$fn = 48;
// 8BitDo Micro, measured
mw = 72.1;
mh = 39.6;
mt = micro_thickness;
mr = 10;                 // corner radius of its body

fit = micro_fit;
t = spring_thickness;
w = 2.4;                 // walls, also the bottom bar
pw = mw + 2 * fit;
ph = mh + 2 * fit;
W = pw + 2 * w;
F1 = 2;                  // clip plate on the screen
FT = 2.6;                // tray floor, carries the dovetail grooves
side_top = ph - 2;       // the walls end here, the tray is open at the top
ov = 1.8;                // the lips reach this far over the face of the Micro
lt = 1.6;                // lip thickness
press = 0.3;             // the lips sit this much below the face, so they press the Micro onto the floor

// Phone: bottom edge at y = 0, screen at z = 0, back at z = -thickness
t_max = 12;
t_min = 6;
gap = t_max + 0.6;
L = 52;                  // spring length up the back
rest = t_min - 1;        // the tip rests here, so a 6 mm phone is still gripped
flare = 8;               // lead-in so the phone slides in
theta = atan((gap - rest) / L);
usb_w = 16;
ch = 4;                  // 45 degree corners, so the clip prints on its side

// Dovetail rails
rx = 30;                 // centre of each rail
rb = 5;                  // width at the plate
rh = 1.6;                // height, flanks at 45 degrees
ry0 = 3;                 // rails start here, the tray stops against them
rclr = 0.2;

echo(str("Fits phones 6 to 12 mm thick, any width. Floor on the screen ", F1 + FT, " mm."));

module rounded(rad) { offset(r = rad) offset(delta = -rad) children(); }
module fillet(rad) { offset(r = -rad) offset(delta = rad) children(); }
module stroke(a, b, d) { hull() { translate(a) circle(d = d); translate(b) circle(d = d); } }
module along_x(width) { rotate([90, 0, 90]) translate([0, 0, -width / 2]) linear_extrude(width) children(); }

module pocket2d() { translate([-pw / 2, 0]) rounded(mr) square([pw, ph + mr]); }

// Outline of the tray and the plate, seen from the screen. The corners are kept small, so the
// bottom bar of the clip runs out to the sides instead of being cut away at the corners.
plan_r = 5;
module plan2d() { translate([-W / 2, -w]) rounded(plan_r) square([W, ph + w]); }

// Same corners as the tray at the bottom, so clip and tray line up; rounded at the tip of the spring.
module arm_plan2d() {
  c = 8;
  hull() {
    intersection() { plan2d(); translate([-W, -w - 1]) square([2 * W, mr + w + 1]); }
    for (s = [-1, 1]) translate([s * (W / 2 - c), L + flare - c]) circle(r = c);
  }
}

// A slab whose top edge is rounded with radius r, in small steps.
module round_top(h, r, n = 6) {
  for (i = [0:n]) {
    a = 90 * i / n;
    linear_extrude(h - r + r * sin(a)) offset(delta = -r * (1 - cos(a))) children();
  }
}

// ---- Clip ----
// Bottom bar seen from the side, rounded only at the back corner. The front corner stays
// square, so the tray sits flush on it.
bend_r = 3;   // inside radius of the bend around the bottom edge of the phone

module bar2d() {
  r = 2;
  hull() {
    translate([-w, -gap - t + r]) square([w, gap + t + F1 - r]);
    translate([-w + r, -gap - t + r]) circle(r = r);
    translate([-0.01, -gap - t]) square(0.01);
  }
}

module front_profile2d() {
  fillet(2.5) union() {
    translate([-w, 0]) square([ph + w, F1]);
    bar2d();
  }
}

// The spring at rest, swung open by a given angle for the preview.
module arm_profile2d(open = 0) {
  root = [0, -gap - t / 2];
  fillet(bend_r) union() {
    bar2d();
    translate(root) rotate(-open) translate(-root) {
      knee = [L, -rest - t / 2];
      stroke(root, knee, t);
      stroke(knee, [L + flare, -rest - t / 2 - flare * 0.6], t);
    }
  }
}

// Dovetail profile across x, at the plate surface.
module dovetail2d(c = 0) {
  polygon([[-rb / 2 - c, -0.01], [rb / 2 + c, -0.01], [rb / 2 + rh + c, rh + c], [-rb / 2 - rh - c, rh + c]]);
}

module rails() {
  // rails run out to the top edge, so the joint is flush there
  intersection() {
    for (s = [-1, 1]) translate([s * rx, ph + 1, F1]) rotate([90, 0, 0]) linear_extrude(ph + 1 - ry0) dovetail2d();
    translate([0, 0, -50]) linear_extrude(100) plan2d();
  }
  // small bump near the top of each rail keeps the tray from sliding off
  for (s = [-1, 1]) translate([s * rx, ph - 6, F1 + rh]) scale([1, 1, 0.5]) sphere(r = 0.5, $fn = 16);
}

// Small diamond studs on the inside of the spring, for grip in every direction.
module studs(open = 0) {
  root = [0, -gap - t / 2];
  translate([0, root[0], root[1]]) rotate([-open, 0, 0]) translate([0, -root[0], -root[1]])
    for (yy = [L - 18:3:L - 3], xx = [-30:3:30]) {
      zc = -gap - t / 2 + yy * tan(theta);
      translate([xx + (round(yy) % 2) * 1.5, yy - t / 2 * sin(theta), zc + t / 2 * cos(theta) - 0.1])
        rotate([theta, 0, 0]) cylinder(r1 = 0.8, r2 = 0, h = 0.6, $fn = 4);
    }
}

// Radius on every edge of the clip. It leaves a core of at least 0.3 mm in the thinnest part,
// so the rounding never eats the spring or the plate away.
er = min(1, (t - 0.3) / 2, (F1 - 0.3) / 2);

module usb2d() { translate([-usb_w / 2, -gap + 0.8]) rounded(2.5) square([usb_w, gap - 1.6]); }

// The clip shrunk by er everywhere, then grown back with a ball, so every edge comes out round.
module clip_core(open = 0) {
  $fn = 20;
  minkowski() {
    difference() {
      union() {
        intersection() {
          along_x(W - 2 * er) offset(delta = -er) front_profile2d();
          translate([0, 0, -50]) linear_extrude(100) offset(delta = -er) plan2d();
        }
        intersection() {
          along_x(W - 2 * er) offset(delta = -er) arm_profile2d(open);
          translate([0, 0, -50]) linear_extrude(100) offset(delta = -er) arm_plan2d();
        }
      }
      // opening for a USB-C plug through the bottom
      translate([0, 2, 0]) rotate([90, 0, 0]) linear_extrude(w + 4) offset(delta = er) usb2d();
    }
    sphere(r = er, $fn = 12);
  }
}

module clip(open = 0) {
  clip_core(open);
  // the face under the tray stays square at its edge, so the tray sits flush on it
  translate([0, 0, F1 - er]) linear_extrude(er) plan2d();
  rails();
  studs(open);
}

// ---- Tray for the Micro ----
// As deep as the Micro, with walls whose top curls inward over the edge of its face. The Micro
// slides in from the open top end and the lips press it onto the floor. The tray slides down
// onto the rails of the clip.

// The walls seen from above, with the lips reaching d over the face of the Micro.
module wall_band2d(d) {
  rounded(0.8) intersection() {
    plan2d();
    translate([-W, -w - 1]) square([2 * W, side_top + w + 1]);
    difference() { plan2d(); offset(delta = -d) pocket2d(); }
  }
}

module tray() {
  zf = F1 + FT;            // top of the floor
  zl = zf + mt - press;    // underside of the lip tips
  zt = zl + lt;            // top of the walls
  rr = 1;                  // rounding on the top of the walls
  n = 8;
  difference() {
    union() {
      translate([0, 0, F1]) round_top(FT, 1.2, 10) plan2d();
      translate([0, 0, F1]) linear_extrude(zt - rr - F1) wall_band2d(0);
      // lips, undersides at 45 degrees so they print without support
      for (i = [1:n]) {
        z0 = zl - ov + ov * i / n;
        translate([0, 0, z0]) linear_extrude(zt - rr - z0) wall_band2d(ov * i / n);
      }
      translate([0, 0, zt - rr - 0.01]) round_top(rr + 0.01, rr, 8) wall_band2d(ov);
    }
    for (s = [-1, 1]) translate([s * rx, ph + 1, F1]) rotate([90, 0, 0])
      linear_extrude(ph + 1 - ry0 + rclr) dovetail2d(rclr);
    // lead-in at the open end: the lips rise so the Micro slides in under them
    intersection() {
      translate([0, 0, zf + 0.5]) linear_extrude(zt) pocket2d();
      along_x(2 * W) polygon([[side_top - 6, zl], [side_top + 1, zl + 1.4], [side_top + 1, zl - 4], [side_top - 6, zl - 4]]);
    }
  }
  // a small catch on each side wall: it drops behind the rounded top corner of the Micro
  for (m = [0, 1]) mirror([m, 0, 0])
    translate([pw / 2 + 0.01, 0, zf + 1.5]) linear_extrude(mt - 5.5)
      polygon([[0, ph - 2.2], [-0.9, ph - 4.2], [-0.9, ph - 4.8], [0, ph - 5.4]]);
}

if (layout == "Assembled") {
  color(color_clip) clip();
  color("Silver") tray();
} else if (layout == "On phone") {
  T = preview_phone_thickness;
  open = atan((gap - rest) / L) - atan((gap - T) / L);
  color(color_clip) { clip(open); tray(); }
  color([0.12, 0.12, 0.12]) translate([0, 0, -T]) linear_extrude(T) translate([-39.75, 0]) rounded(9) square([79.5, 163.5]);
  for (i = [0, 1]) color("LightSteelBlue") translate([-35, ph + 3 + i * 53, -0.3]) cube([70, 52.5, 0.3]);
  color("SteelBlue") translate([0, fit, F1 + FT]) linear_extrude(mt) translate([-mw / 2, 0]) rounded(mr) square([mw, mh]);
} else {
  color(color_clip) {
    // clip on its side, so the spring bends along its layers
    translate([-20, 0, W / 2]) rotate([0, -90, 0]) clip();
    // tray flat, floor down
    translate([45, 0, -F1]) tray();
  }
}