epaper_door_case/cpu_case.scad

// ============================================================
//  XIAO ePaper Display Board EE04 — 3D-Printed Case
//  OpenSCAD parametric model
// ============================================================
use <ee04.scad>

/* [Preview] */
SHOW_BOARD  = true;
SHOW_LID    = true;
SHOW_BASE   = true;
EXPLODE     = 65;      // mm to pull lid out in Y- for inspection (try 40)

/* [Board Dimensions — from EE04 STL] */
PCB_L = 80.00;   // board length  (case_x axis)
PCB_W = 41.22;   // board width   (case_y axis)
PCB_T =  1.93;   // PCB thickness

// Component heights measured from PCB bottom face:
COMP_MAX_Z  = 7.29;   // tallest component (XIAO module)
COMP_SIDE_Z = 3.82;   // tallest component on +Y wall (buttons, USB-C)

/* [Cutout Positions — from STL geometry, PCB-origin-relative] */

// ---- +Y wall: Sliding power switch ----
PWR_CX      =  10.3;   // PCB-relative case_x centre
PWR_W       =   5.0;   // slot width
PWR_H       =   2.5;   // slot height
PWR_CZ      =   3.8;   // height above PCB bottom

// ---- +Y wall: USB-C port ----
USBC_CX     =  65.65;
USBC_W      =  11.5;
USBC_H      =   4.8;
USBC_CZ     =   4.4;

// ---- +Y wall: 3× user buttons + 1× reset ----
BTN_CX      = [48.4, 39.1, 29.8, 20.4];   // PCB-relative case_x centres
BTN_D       =   4.5;
BTN_CZ      =   3.7;

/* [Case Parameters] */
WALL          =  2.0;   // wall thickness
FLOOR         =  2.0;   // base floor thickness (thicker for thread engagement)
CORNER_R      =  2.5;   // XY corner fillet radius
SCREW_D       =  3.2;   // M3 tap drill diameter
BOSS_D        =  6.0;   // PCB standoff boss outer diameter
BOSS_H        =  2.0;   // standoff boss height; PCB bottom sits flush on boss top

/* [Locating Studs] */
STUD_CLEAR  =  0.10;   // radial clearance per side — close (non-interference) fit in SLA resin
STUD_H      =  PCB_T + 1.0;   // stud cylinder height above boss top: through PCB + 1 mm proud
STUD_R      =  (SCREW_D - 2*STUD_CLEAR) / 2;   // stud pin radius (= cylinder + dome radius)

/* [PCB Standoff Positions — relative to PCB origin] */
PCB_BOSS_X1   =  2.5;
PCB_BOSS_X2   =  PCB_L - 2.5;
PCB_BOSS_Y1   =  2.5;
PCB_BOSS_Y2   =  PCB_W - 2.5;

/* [Interior Clearances — PCB edge to interior wall face] */
CLR_XN   =   5.0;   // X- side
CLR_XP   =  15.0;   // X+ side (JST cable routing)
CLR_YN   =  15.0;   // Y- side (FPC routing; lid inserts from here)
CLR_YP   =   0.5;   // Y+ side (snug against button/USB-C wall)
CLR_LID  =   5.0;   // from tallest component top to lid underside

/* [Sliding Lid] */
LID_T       =  1.5;   // lid ceiling thickness
FLANGE_H    =  3.0;   // Z height of retention flanges (base + lid); drives lid placement and Y- wall step
FLANGE_W    =  FLANGE_H * tan(30);   // flange width — 30° from vertical (60° from horizontal), printable without support
SLIDE_CLEAR =  0.40;  // clearance between flange/rib and groove/channel on all mating faces (0.4 mm suits typical FDM tolerances)

/* [Computed] */
PCB_Z    = FLOOR + BOSS_H;

// Base inner height: floor to lid underside ≈ BASE_H (flange rests on groove floor)
BASE_INNER_H = BOSS_H + COMP_MAX_Z + CLR_LID;
BASE_H       = FLOOR + BASE_INNER_H;

PCB_OX   = WALL + CLR_XN;
PCB_OY   = WALL + CLR_YN;

CAV_L    = CLR_XN + PCB_L + CLR_XP;
CAV_W    = CLR_YN + PCB_W + CLR_YP;
OUT_L    = CAV_L + 2*WALL;
OUT_W    = CAV_W + 2*WALL;

LID_H     = FLANGE_H + LID_T;
LID_Y_LEN = CAV_W;   // flange length; lid Y+ end stops against Y+ interior wall

// ============================================================
//  HELPERS
// ============================================================
module rounded_box(l, w, h, r) {
    hull()
        for (dx = [r, l-r], dy = [r, w-r])
            translate([dx, dy, 0]) cylinder(r=r, h=h, $fn=32);
}

// Standoff boss: screw variant has through-hole; stud variant has locating pin instead.
// Diagonal (X1,Y1)+(X2,Y2) → studs; (X1,Y2)+(X2,Y1) → screws.
module pcb_boss(px, py, stud=false) {
    translate([PCB_OX + px, PCB_OY + py, FLOOR]) {
        difference() {
            cylinder(d=BOSS_D, h=BOSS_H + 0.01, $fn=24);
            if (!stud)
                translate([0, 0, -0.1])
                    cylinder(d=SCREW_D * 0.7, h=BOSS_H + 0.2, $fn=18);
        }
        if (stud)
            translate([0, 0, BOSS_H]) {
                cylinder(r=STUD_R, h=STUD_H, $fn=24);
                translate([0, 0, STUD_H])
                    sphere(r=STUD_R, $fn=24);
            }
    }
}

// ============================================================
//  BASE
// ============================================================
module base() {
    color("#004B49") {
        difference() {
            rounded_box(OUT_L, OUT_W, BASE_H, CORNER_R);

            // Interior cavity (open top)
            translate([WALL, WALL, FLOOR])
                cube([CAV_L, CAV_W, BASE_H]);

            // ---- Boss screw holes through 50 % of floor (screw diagonal only) ----
            for (pos = [[PCB_BOSS_X1, PCB_BOSS_Y2], [PCB_BOSS_X2, PCB_BOSS_Y1]])
                translate([PCB_OX + pos[0], PCB_OY + pos[1], FLOOR * 0.5 - 0.1])
                    cylinder(d=SCREW_D * 0.7, h=FLOOR * 0.5 + 0.2, $fn=18);

            // ---- +Y wall cutouts ----

            // Sliding power switch slot
            translate([PCB_OX + PWR_CX - PWR_W/2,
                       OUT_W - WALL - 0.1,
                       PCB_Z + PWR_CZ - PWR_H/2])
                cube([PWR_W, WALL + 0.2, PWR_H]);

            // USB-C slot
            translate([PCB_OX + USBC_CX - USBC_W/2,
                       OUT_W - WALL - 0.1,
                       PCB_Z + USBC_CZ - USBC_H/2])
                cube([USBC_W, WALL + 0.2, USBC_H]);

            // 4× button holes (3 user + 1 reset)
            for (bcx = BTN_CX)
                translate([PCB_OX + bcx,
                           OUT_W + 0.1,
                           PCB_Z + BTN_CZ])
                    rotate([90, 0, 0])
                        cylinder(d=BTN_D, h=WALL + 0.3, $fn=32);

            // ---- Y- wall step for lid flange clearance ----
            // Remove the full Y- wall above z=BASE_H-FLANGE_H-SLIDE_CLEAR so the lid
            // flanges can enter freely from Y-.
            translate([-0.1, -0.1, BASE_H - FLANGE_H - SLIDE_CLEAR])
                cube([OUT_L + 0.2, WALL + 0.2, FLANGE_H + SLIDE_CLEAR + 0.1]);
        }

        // Standoff bosses (added outside diff so cavity doesn't subtract them)
        pcb_boss(PCB_BOSS_X1, PCB_BOSS_Y1, stud=true);   // stud diagonal
        pcb_boss(PCB_BOSS_X2, PCB_BOSS_Y2, stud=true);   // stud diagonal
        pcb_boss(PCB_BOSS_X1, PCB_BOSS_Y2, stud=false);  // screw diagonal
        pcb_boss(PCB_BOSS_X2, PCB_BOSS_Y1, stud=false);  // screw diagonal
    }

    // Lid-retention flanges — right triangles, wide face flush with case top (z=BASE_H),
    // tip pointing down to (WALL, BASE_H-FLANGE_H). Hypotenuse faces down-into-cavity;
    // lid flanges slide underneath it for Z retention.
    color("#2C3863") {
        hull() {
            translate([WALL, WALL, BASE_H - 0.01])
                cube([FLANGE_W, CAV_W, 0.01]);
            translate([WALL, WALL, BASE_H - FLANGE_H])
                cube([0.01, CAV_W, 0.01]);
        }
        hull() {
            translate([OUT_L - WALL - FLANGE_W, WALL, BASE_H - 0.01])
                cube([FLANGE_W, CAV_W, 0.01]);
            translate([OUT_L - WALL - 0.01, WALL, BASE_H - FLANGE_H])
                cube([0.01, CAV_W, 0.01]);
        }
    }
}

// ============================================================
//  LID  (slide-on; enters from Y- face, closes toward Y+)
//  Print upside-down (ceiling on build plate).
//  z=0 = bottom of flanges; z=FLANGE_H = ceiling underside.
//  Flanges sit inside cavity and ride on base retention flange hypotenuses.
// ============================================================
module lid() {
    // Flanges: right triangles in XZ; hypotenuse at reciprocal angle to base retention flanges.
    // Wide vertical face at x=WALL+FLANGE_W (inner), tip at bottom-wall-face — same
    // (-FLANGE_W, -FLANGE_H) hypotenuse slope as base flanges so they mate when lid slides in.
    color("#2C3863") {
        // Left (X-) flange
        hull() {
            translate([WALL + FLANGE_W - SLIDE_CLEAR - 0.01, 0, 0])
                cube([0.01, LID_Y_LEN, FLANGE_H - SLIDE_CLEAR]);
            translate([WALL + SLIDE_CLEAR, 0, -0.005])
                cube([0.01, LID_Y_LEN, 0.01]);
        }
        // Right (X+) flange
        hull() {
            translate([OUT_L - WALL - FLANGE_W + SLIDE_CLEAR, 0, 0])
                cube([0.01, LID_Y_LEN, FLANGE_H - SLIDE_CLEAR]);
            translate([OUT_L - WALL - SLIDE_CLEAR - 0.01, 0, -0.005])
                cube([0.01, LID_Y_LEN, 0.01]);
        }

        // Interior ribs — 2 mm wide, on cavity face of each flange
        translate([WALL + FLANGE_W - SLIDE_CLEAR, 0, 0])
            cube([2.0, LID_Y_LEN, FLANGE_H]);
        translate([OUT_L - WALL - FLANGE_W + SLIDE_CLEAR - 2.0, 0, 0])
            cube([2.0, LID_Y_LEN, FLANGE_H]);

        // Y+ stop rib — full-width cross member spanning between rails, stiffens closed end
        translate([WALL + FLANGE_W - SLIDE_CLEAR + 2.0, LID_Y_LEN - 3, FLANGE_H - 3])
            cube([OUT_L - 2*WALL - 2*FLANGE_W + 2*SLIDE_CLEAR - 4.0, 3, 3]);
    }

    color("#004B49") {
        // Ceiling plate — matches base footprint (OUT_L × OUT_W) with CORNER_R rounding
        translate([0, -WALL, FLANGE_H])
            rounded_box(OUT_L, OUT_W, LID_T, CORNER_R);

        // Y- lip — same rounded_box profile clipped to the Y- wall zone so the
        // lip corners match the base exterior corners
        intersection() {
            translate([0, -WALL, -SLIDE_CLEAR])
                rounded_box(OUT_L, OUT_W, FLANGE_H + SLIDE_CLEAR, CORNER_R);
            translate([-0.1, -WALL - 0.1, -SLIDE_CLEAR - 0.1])
                cube([OUT_L + 0.2, WALL + 0.2, FLANGE_H + SLIDE_CLEAR + 0.2]);
        }
    }
}

// ============================================================
//  BOARD PLACEMENT
//  EE04() XY-normalises the STL (board left/front at origin).
//  +1.925 corrects for STL native Z (PCB bottom at Z=−1.925) so
//  the PCB bottom face lands exactly at PCB_Z.
// ============================================================
module stl_board() {
    translate([PCB_OX, PCB_OY, PCB_Z])
        EE04();
}

// ============================================================
//  ASSEMBLY
// ============================================================
if (SHOW_BASE)  base();

if (SHOW_LID)
    translate([0,
               WALL - EXPLODE,
               BASE_H - FLANGE_H])
        lid();

if (SHOW_BOARD) stl_board();