tier-3-butt-hinge / claude-sonnet-4-6

// Butt Hinge - 180° open state
// Pin axis along Y, leaves flat in XZ plane at z=0..2

// Parameters
leaf_w = 25;    // width (x direction)
leaf_h = 30;    // height (y direction)
leaf_t = 2;     // thickness (z direction)

pin_d = 4;
pin_r = pin_d / 2;
pin_len = 32;

knuckle_od = 8;
knuckle_or = knuckle_od / 2;
knuckle_id = 4.6;
knuckle_ir = knuckle_id / 2;
knuckle_h = 6;

// Screw holes
screw_d = 3.2;
cs_d = 6;
cs_depth = 1;
screw_count = 3;
screw_pitch = 8;
screw_x_offset = leaf_w / 2; // center of screw zone

// Left leaf: x from -leaf_w to 0, knuckles at x=0 side
// Right leaf: x from 0 to leaf_w, knuckles at x=0 side
// Both leaves lie in z = -leaf_t to 0 plane (top face at z=0)

module countersunk_hole(depth=leaf_t) {
    // Countersink: cone from diameter cs_d at top to screw_d, depth cs_depth
    // Then through hole screw_d for remaining depth
    union() {
        cylinder(d1=cs_d, d2=screw_d, h=cs_depth, $fn=32);
        translate([0,0,-depth+cs_depth])
            cylinder(d=screw_d, h=depth-cs_depth+0.01, $fn=32);
    }
}

module knuckle() {
    difference() {
        cylinder(d=knuckle_od, h=knuckle_h, $fn=32);
        translate([0,0,-0.1])
            cylinder(d=knuckle_id, h=knuckle_h+0.2, $fn=32);
    }
}

module left_leaf() {
    // Leaf body: x from -leaf_w to 0, y from -1 to 29 (pin offset by 1), z from -leaf_t to 0
    // Pin starts at y=-1, so leaf y from 0 to 30 mapped to pin y 0..30
    // Actually: leaf y from 0 to 30, knuckles centered on x=0 edge
    
    difference() {
        union() {
            // Main leaf plate
            translate([-leaf_w, 0, -leaf_t])
                cube([leaf_w, leaf_h, leaf_t]);
            
            // Left leaf knuckles: positions 0,2,4 (y=0,12,24) -> centers at y=3,15,27
            // knuckle 1: y=0..6, knuckle 3: y=12..18, knuckle 5: y=24..30
            for(i = [0, 2, 4]) {
                translate([0, i*knuckle_h, -knuckle_od/2])
                    rotate([-90, 0, 0])
                        // knuckle centered on x=0, extending in +x direction around pin
                        // Actually knuckle is a cylinder along y axis
                        translate([0, 0, 0])
                            knuckle();
            }
        }
        
        // Screw holes on leaf (top face z=0, going down)
        // Screws along y axis, x centered at -leaf_w/2
        for(i = [0:screw_count-1]) {
            translate([-leaf_w/2, 4 + i*screw_pitch, 0])
                rotate([180, 0, 0])
                    countersunk_hole(leaf_t);
        }
    }
}

module right_leaf() {
    difference() {
        union() {
            // Main leaf plate
            translate([0, 0, -leaf_t])
                cube([leaf_w, leaf_h, leaf_t]);
            
            // Right leaf knuckles: positions 1,3 (y=6..12, y=18..24)
            for(i = [1, 3]) {
                translate([0, i*knuckle_h, -knuckle_od/2])
                    rotate([-90, 0, 0])
                        knuckle();
            }
        }
        
        // Screw holes
        for(i = [0:screw_count-1]) {
            translate([leaf_w/2, 4 + i*screw_pitch, 0])
                rotate([180, 0, 0])
                    countersunk_hole(leaf_t);
        }
    }
}

module pin() {
    translate([0, -1, -knuckle_od/2])
        rotate([-90, 0, 0])
            cylinder(d=pin_d, h=pin_len, $fn=32);
}

// Render all parts
color("silver") left_leaf();
color("silver") right_leaf();
color("gold")   pin();

// Butt Hinge - 180° open state
// Units: mm

// Parameters
leaf_width  = 25;   // X direction (away from pin)
leaf_height = 30;   // Y direction (along pin axis)
leaf_thick  = 2;    // Z direction

pin_dia     = 4;
pin_r       = pin_dia / 2;
pin_len     = 32;   // 1mm overhang each end

knuckle_od  = 8;
knuckle_or  = knuckle_od / 2;
knuckle_id  = pin_dia + 0.3;  // 4.6mm
knuckle_ir  = knuckle_id / 2;
knuckle_h   = 6;    // each knuckle height (30/5)

// Countersink screw holes (M3)
cs_top_dia  = 6;
cs_depth    = 1;
cs_hole_dia = 3.2;
screw_x_offset = leaf_width / 2;  // center of screw in X on the leaf
// 3 screws per leaf, spaced 8mm apart in Y, centered on leaf_height
screw_y_positions = [
    leaf_height/2 - 8*1,  // 7
    leaf_height/2,         // 15
    leaf_height/2 + 8*1   // 23
];

// Left leaf knuckles: positions 0,2,4 (outer two + center)
// Y start positions: 0,6,12,18,24  -> knuckle centers at 3,9,15,21,27
// Left: segments 0,2,4 -> centers at 3, 15, 27
// Right: segments 1,3  -> centers at 9, 21

left_knuckle_centers  = [3, 15, 27];
right_knuckle_centers = [9, 21];

$fn = 64;

// ─── Modules ───────────────────────────────────────────────────

module knuckle(center_y) {
    translate([0, center_y - knuckle_h/2, -knuckle_or])
    rotate([-90, 0, 0])
    difference() {
        cylinder(h = knuckle_h, r = knuckle_or);
        cylinder(h = knuckle_h, r = knuckle_ir);
    }
}

// A leaf with knuckles and screw holes.
// leaf_side: -1 = left (extends in -X), +1 = right (extends in +X)
// knuckle_centers: list of Y centers for knuckles
module leaf(leaf_side, knuckle_centers) {
    // leaf body
    // The leaf flat face is at Z=0 (top surface).
    // Leaf thickness goes downward: Z from -leaf_thick to 0.
    // Knuckle center is at X=0; leaf extends in leaf_side * X direction.
    
    difference() {
        union() {
            // Flat leaf plate
            translate([leaf_side > 0 ? 0 : -leaf_width,
                       0,
                       -leaf_thick])
                cube([leaf_width, leaf_height, leaf_thick]);
            
            // Knuckles
            for (cy = knuckle_centers) {
                knuckle(cy);
            }
        }
        
        // Screw countersinks
        // Screws placed at X = leaf_side * (leaf_width * 0.5)
        sx = leaf_side * (leaf_width / 2);
        for (sy = screw_y_positions) {
            translate([sx, sy, 0]) {
                // Countersink taper: from dia 6 at Z=0 to dia 3.2 at Z=-cs_depth
                cylinder(h = cs_depth,
                         r1 = cs_top_dia / 2,
                         r2 = cs_hole_dia / 2);
                // Through hole
                translate([0, 0, -leaf_thick])
                    cylinder(h = leaf_thick, r = cs_hole_dia / 2);
            }
        }
        
        // Trim knuckle area flush with leaf (remove knuckle overlap below leaf)
        // Actually knuckles are centered at Z=0 so they protrude above.
        // We need to cut the flat leaf area where knuckles intersect.
        // The leaf is at Z -leaf_thick..0; knuckles protrude from Z -knuckle_or..+knuckle_or
        // so below the leaf (Z < -leaf_thick) knuckle material should be removed.
        // We'll cut below -leaf_thick in the leaf span.
        translate([leaf_side > 0 ? 0 : -leaf_width,
                   0,
                   -knuckle_or - 1])
            cube([leaf_width, leaf_height, knuckle_or - leaf_thick + 1 + 0.01]);
    }
}

module pin_axis() {
    // Pin along Y axis, centered at origin, length 32mm
    translate([0, -pin_len/2, 0])
    rotate([-90, 0, 0])
    cylinder(h = pin_len, r = pin_r);
}

// ─── Assembly ──────────────────────────────────────────────────

// Left leaf: extends in -X direction
color("silver")
leaf(-1, left_knuckle_centers);

// Right leaf: extends in +X direction
color("silver")
leaf(1, right_knuckle_centers);

// Pin axis
color("gold")
pin_axis();

// Butt Hinge - 180° open state
// Units: mm

// Parameters
leaf_width  = 25;   // X direction (away from pin)
leaf_height = 30;   // Y direction (along pin axis)
leaf_thick  = 2;    // Z direction

pin_dia     = 4;
pin_r       = pin_dia / 2;
pin_len     = 32;   // 1mm overhang each end

knuckle_od  = 8;
knuckle_or  = knuckle_od / 2;
knuckle_id  = pin_dia + 0.3;  // 4.6mm
knuckle_ir  = knuckle_id / 2;
knuckle_h   = 6;    // each knuckle height (30/5)

// Countersink screw holes (M3)
cs_top_dia  = 6;
cs_depth    = 1;
cs_hole_dia = 3.2;
screw_x_offset = leaf_width / 2;  // center of screw in X on the leaf
// 3 screws per leaf, spaced 8mm apart in Y, centered on leaf_height
screw_y_positions = [
    leaf_height/2 - 8*1,  // 7
    leaf_height/2,         // 15
    leaf_height/2 + 8*1   // 23
];

// Left leaf knuckles: positions 0,2,4 (outer two + center)
// Y start positions: 0,6,12,18,24  -> knuckle centers at 3,9,15,21,27
// Left: segments 0,2,4 -> centers at 3, 15, 27
// Right: segments 1,3  -> centers at 9, 21

left_knuckle_centers  = [3, 15, 27];
right_knuckle_centers = [9, 21];

$fn = 64;

// ─── Modules ───────────────────────────────────────────────────

module knuckle(center_y) {
    translate([0, center_y - knuckle_h/2, -knuckle_or])
    rotate([-90, 0, 0])
    difference() {
        cylinder(h = knuckle_h, r = knuckle_or);
        cylinder(h = knuckle_h, r = knuckle_ir);
    }
}

// A leaf with knuckles and screw holes.
// leaf_side: -1 = left (extends in -X), +1 = right (extends in +X)
// knuckle_centers: list of Y centers for knuckles
module leaf(leaf_side, knuckle_centers) {
    // leaf body
    // The leaf flat face is at Z=0 (top surface).
    // Leaf thickness goes downward: Z from -leaf_thick to 0.
    // Knuckle center is at X=0; leaf extends in leaf_side * X direction.
    
    difference() {
        union() {
            // Flat leaf plate
            translate([leaf_side > 0 ? 0 : -leaf_width,
                       0,
                       -leaf_thick])
                cube([leaf_width, leaf_height, leaf_thick]);
            
            // Knuckles
            for (cy = knuckle_centers) {
                knuckle(cy);
            }
        }
        
        // Screw countersinks
        // Screws placed at X = leaf_side * (leaf_width * 0.5)
        sx = leaf_side * (leaf_width / 2);
        for (sy = screw_y_positions) {
            translate([sx, sy, 0]) {
                // Countersink taper: from dia 6 at Z=0 to dia 3.2 at Z=-cs_depth
                cylinder(h = cs_depth,
                         r1 = cs_top_dia / 2,
                         r2 = cs_hole_dia / 2);
                // Through hole
                translate([0, 0, -leaf_thick])
                    cylinder(h = leaf_thick, r = cs_hole_dia / 2);
            }
        }
        
        // Trim knuckle area flush with leaf (remove knuckle overlap below leaf)
        // Actually knuckles are centered at Z=0 so they protrude above.
        // We need to cut the flat leaf area where knuckles intersect.
        // The leaf is at Z -leaf_thick..0; knuckles protrude from Z -knuckle_or..+knuckle_or
        // so below the leaf (Z < -leaf_thick) knuckle material should be removed.
        // We'll cut below -leaf_thick in the leaf span.
        translate([leaf_side > 0 ? 0 : -leaf_width,
                   0,
                   -knuckle_or - 1])
            cube([leaf_width, leaf_height, knuckle_or - leaf_thick + 1 + 0.01]);
    }
}

module pin_axis() {
    // Pin along Y axis, centered at origin, length 32mm
    translate([0, -pin_len/2, 0])
    rotate([-90, 0, 0])
    cylinder(h = pin_len, r = pin_r);
}

// ─── Assembly ──────────────────────────────────────────────────

// Left leaf: extends in -X direction
color("silver")
leaf(-1, left_knuckle_centers);

// Right leaf: extends in +X direction
color("silver")
leaf(1, right_knuckle_centers);

// Pin axis
color("gold")
pin_axis();

// Butt Hinge - 180° open position
// Pin axis along Y, leaves extend in -X and +X directions

// Parameters
leaf_width  = 25;   // X direction (when open)
leaf_length = 30;   // Y direction (along pin)
leaf_thick  = 2;    // Z direction

pin_dia     = 4;
pin_r       = pin_dia / 2;
pin_length  = 32;   // 1mm overhang each end

knuckle_od  = 8;
knuckle_or  = knuckle_od / 2;
knuckle_id  = pin_dia + 0.3;  // 4.3mm  ← clearance bore
knuckle_ir  = knuckle_id / 2;
knuckle_h   = 6;    // each knuckle height

// Screw holes (M3 countersunk)
screw_cs_dia   = 6;
screw_cs_depth = 1;
screw_thru_dia = 3.2;
screw_count    = 3;
screw_pitch    = 8;   // Y spacing
// screw column is centred on leaf_length/2 in Y, spaced 8mm apart
// positions: -8, 0, +8  relative to leaf centre → 7, 15, 23 in Y

// Screw X position: middle of the leaf (away from knuckle side)
screw_x = -(leaf_width / 2);   // for left leaf  (negative side)

$fn = 48;

// ─────────────────────────────────────────────
// Helper: single countersunk hole (centred at origin, going -Z)
module cs_hole() {
    // countersink taper (cone, wider at top)
    cylinder(h = screw_cs_depth,
             r1 = screw_cs_dia / 2,
             r2 = screw_thru_dia / 2);
    // through hole
    translate([0, 0, -leaf_thick])
        cylinder(h = leaf_thick + screw_cs_depth + 0.01,
                 r = screw_thru_dia / 2);
}

// ─────────────────────────────────────────────
// Knuckle: a tube of height knuckle_h, centred at origin, axis = Z
module knuckle() {
    difference() {
        cylinder(h = knuckle_h, r = knuckle_or, center = true);
        cylinder(h = knuckle_h + 0.02, r = knuckle_ir, center = true);
    }
}

// ─────────────────────────────────────────────
// Left leaf  (x ≤ 0 side)
// Leaf flat face at z = 0, body goes to z = -leaf_thick
// Knuckles protrude above the flat face (z = 0 … knuckle_od/2 from axis)
// but we keep knuckle axis at x=0, z=0 and orient them along Y.
//
// Knuckle positions along Y (knuckle centres):
//   Left leaf  owns knuckles 1,3,5  → Y centres: 3, 15, 27  (0-indexed segments 0,2,4)
//   Right leaf owns knuckles 2,4    → Y centres: 9, 21       (segments 1,3)
//
// Knuckle axis is Y, so we rotate the tube 90° around X.

left_knuckle_y  = [3, 15, 27];   // centres in Y for left leaf
right_knuckle_y = [9, 21];       // centres in Y for right leaf

// The leaf starts at Y=0 and ends at Y=leaf_length (30).
// Knuckle outer radius sits on the x=0 line; leaf extends to x = -leaf_width.

module left_leaf() {
    difference() {
        union() {
            // flat plate
            translate([-leaf_width, 0, -leaf_thick])
                cube([leaf_width, leaf_length, leaf_thick]);

            // knuckles (rotated 90° so axis is Y)
            for (yc = left_knuckle_y) {
                translate([0, yc, 0])
                    rotate([90, 0, 0])
                        knuckle();
            }
        }

        // countersunk screw holes — placed on the leaf, away from knuckle side
        // X centre at -leaf_width/2, Y positions centred on leaf
        for (i = [0 : screw_count - 1]) {
            ypos = (leaf_length - (screw_count - 1) * screw_pitch) / 2
                   + i * screw_pitch;
            translate([-leaf_width / 2, ypos, 0])
                cs_hole();
        }
    }
}

module right_leaf() {
    difference() {
        union() {
            // flat plate
            translate([0, 0, -leaf_thick])
                cube([leaf_width, leaf_length, leaf_thick]);

            // knuckles
            for (yc = right_knuckle_y) {
                translate([0, yc, 0])
                    rotate([90, 0, 0])
                        knuckle();
            }
        }

        // countersunk screw holes
        for (i = [0 : screw_count - 1]) {
            ypos = (leaf_length - (screw_count - 1) * screw_pitch) / 2
                   + i * screw_pitch;
            translate([leaf_width / 2, ypos, 0])
                cs_hole();
        }
    }
}

// ─────────────────────────────────────────────
// Pin: along Y axis, centred so it overhangs 1mm at each end
module pin() {
    translate([0, -1, 0])          // shift so Y=-1 … Y=31
        rotate([-90, 0, 0])
            cylinder(h = pin_length, r = pin_r);
}

// ─────────────────────────────────────────────
// Assembly — 180° open: both leaves in the same Z=0 plane
color("silver", 0.9) left_leaf();
color("silver", 0.9) right_leaf();
color("gold",   1.0) pin();

// Butt Hinge - 180° open position
// Pin axis along Y, leaves extend in -X and +X directions

$fn = 64;

// Parameters
leaf_width  = 25;   // X extent of flat plate portion
leaf_length = 30;   // Y direction (along pin)
leaf_thick  = 2;    // Z thickness

pin_dia     = 4;
pin_r       = pin_dia / 2;
pin_length  = 32;   // 1mm overhang each end (-1 to 31)

knuckle_od  = 8;
knuckle_or  = knuckle_od / 2;   // 4
knuckle_id  = pin_dia + 0.3;    // 4.3mm clearance bore
knuckle_ir  = knuckle_id / 2;
knuckle_h   = 6;                 // each knuckle segment height

// Screw holes (M3 countersunk)
screw_cs_dia   = 6;
screw_cs_depth = 1;
screw_thru_dia = 3.2;
screw_count    = 3;
screw_pitch    = 8;

// Knuckle Y centres:
//   Left leaf  (3 knuckles): segments 0,2,4 → Y centres 3, 15, 27
//   Right leaf (2 knuckles): segments 1,3   → Y centres 9, 21
left_knuckle_y  = [3, 15, 27];
right_knuckle_y = [9, 21];

// The pin/knuckle axis is at X=0, Z=0.
// Leaf flat face is at Z=0 (top surface), body goes down to Z=-leaf_thick.
// Leaf plate extends from X=0 outward (left: -leaf_width, right: +leaf_width).
// Knuckle centre is at X=0, Z=0; lower half (Z<0) merges into plate edge.

// ─────────────────────────────────────────────
// Knuckle tube, axis along Y, centred at origin
module knuckle_tube() {
    rotate([90, 0, 0])
        difference() {
            cylinder(h = knuckle_h, r = knuckle_or, center = true);
            cylinder(h = knuckle_h + 0.02, r = knuckle_ir, center = true);
        }
}

// ─────────────────────────────────────────────
// Countersunk hole: top surface at Z=0, going downward through leaf_thick
// Wider at top (Z=0), narrows to thru-hole diameter
module cs_hole() {
    union() {
        // countersink cone: top z=0 dia=screw_cs_dia, bottom z=-screw_cs_depth dia=screw_thru_dia
        translate([0, 0, -screw_cs_depth])
            cylinder(h = screw_cs_depth + 0.01,
                     r1 = screw_thru_dia / 2,
                     r2 = screw_cs_dia / 2);
        // through hole from countersink bottom to leaf bottom
        translate([0, 0, -(leaf_thick + 0.01)])
            cylinder(h = leaf_thick - screw_cs_depth + 0.02,
                     r = screw_thru_dia / 2);
    }
}

// ─────────────────────────────────────────────
// Screw hole Y positions (centred on leaf_length)
function screw_y(i) =
    (leaf_length - (screw_count - 1) * screw_pitch) / 2 + i * screw_pitch;

// ─────────────────────────────────────────────
// Left leaf: plate extends in -X direction, knuckles at X=0
module left_leaf() {
    difference() {
        union() {
            // Flat plate: from X=-leaf_width to X=0, Y=0 to Y=30, Z=-leaf_thick to Z=0
            translate([-leaf_width, 0, -leaf_thick])
                cube([leaf_width, leaf_length, leaf_thick]);

            // Knuckles at X=0 axis
            for (yc = left_knuckle_y) {
                translate([0, yc, 0])
                    knuckle_tube();
            }
        }

        // Countersunk screw holes on flat part
        // X centre at -leaf_width/2 (middle of plate away from hinge)
        for (i = [0 : screw_count - 1]) {
            translate([-leaf_width / 2, screw_y(i), 0])
                cs_hole();
        }

        // Remove pin bore through all knuckles
        translate([0, -1, 0])
            rotate([-90, 0, 0])
                cylinder(h = pin_length + 2, r = knuckle_ir);
    }
}

// ─────────────────────────────────────────────
// Right leaf: plate extends in +X direction, knuckles at X=0
module right_leaf() {
    difference() {
        union() {
            // Flat plate: from X=0 to X=+leaf_width
            translate([0, 0, -leaf_thick])
                cube([leaf_width, leaf_length, leaf_thick]);

            // Knuckles at X=0 axis
            for (yc = right_knuckle_y) {
                translate([0, yc, 0])
                    knuckle_tube();
            }
        }

        // Countersunk screw holes
        for (i = [0 : screw_count - 1]) {
            translate([leaf_width / 2, screw_y(i), 0])
                cs_hole();
        }

        // Remove pin bore through all knuckles
        translate([0, -1, 0])
            rotate([-90, 0, 0])
                cylinder(h = pin_length + 2, r = knuckle_ir);
    }
}

// ─────────────────────────────────────────────
// Pin: Y from -1 to +31 (1mm overhang each end)
module pin() {
    translate([0, -1, 0])
        rotate([-90, 0, 0])
            cylinder(h = pin_length, r = pin_r);
}

// ─────────────────────────────────────────────
// Assembly
color([0.75, 0.75, 0.78], 1.0) left_leaf();
color([0.75, 0.75, 0.78], 1.0) right_leaf();
color([0.85, 0.70, 0.20], 1.0) pin();

// Butt Hinge - 180° open position
// Pin axis along Y, leaves extend in -X and +X directions

$fn = 64;

// Parameters
leaf_width  = 25;   // X extent of flat plate portion
leaf_length = 30;   // Y direction (along pin)
leaf_thick  = 2;    // Z thickness

pin_dia     = 4;
pin_r       = pin_dia / 2;
pin_length  = 32;   // 1mm overhang each end

knuckle_od  = 8;
knuckle_or  = knuckle_od / 2;   // 4mm
knuckle_id  = pin_dia + 0.3;    // 4.3mm clearance bore
knuckle_ir  = knuckle_id / 2;
knuckle_h   = 6;                 // each knuckle height

// Knuckle Y centres (each segment 6mm, centres at 3,9,15,21,27)
// Left leaf  (3 knuckles): segments 0,2,4 → Y centres 3, 15, 27
// Right leaf (2 knuckles): segments 1,3   → Y centres 9, 21
left_knuckle_y  = [3, 15, 27];
right_knuckle_y = [9, 21];

// Knuckle protrudes above the plate surface (Z=0).
// Knuckle axis (pin centre) is at Z = knuckle_or = 4mm above plate top face.
// So knuckle occupies Z = 0 to Z = knuckle_od = 8mm (diameter).
// The leaf plate sits at Z = -leaf_thick to Z = 0.
// A fillet block fills between plate top (Z=0) and knuckle bottom tangent line.
knuckle_z = knuckle_or;   // pin axis height above plate top face

// Screw holes (M3 countersunk)
screw_cs_dia   = 6;
screw_cs_depth = 1;
screw_thru_dia = 3.2;
screw_count    = 3;
screw_pitch    = 8;

function screw_y(i) =
    (leaf_length - (screw_count - 1) * screw_pitch) / 2 + i * screw_pitch;

// ─────────────────────────────────────────────
// Single knuckle tube, axis along Y
// Placed so axis is at [0, yc, knuckle_z]
module knuckle_tube(yc) {
    translate([0, yc, knuckle_z])
        rotate([90, 0, 0])
            difference() {
                cylinder(h = knuckle_h, r = knuckle_or, center = true);
                cylinder(h = knuckle_h + 0.02, r = knuckle_ir, center = true);
            }
}

// Fillet/web block connecting knuckle base to plate surface
// A square-ish block that fills the gap between the cylinder and the flat plate
module knuckle_base_fill(yc) {
    translate([0, yc, 0])
        rotate([90, 0, 0])
            // Hull between a rectangle at Z=0 and the cylinder cross-section
            linear_extrude(height = knuckle_h, center = true)
                hull() {
                    // plate-level footprint (thin rectangle)
                    translate([0, 0, 0])
                        square([knuckle_od, 0.01], center = true);
                    // knuckle circle at its axis height
                    translate([0, knuckle_z, 0])
                        circle(r = knuckle_or);
                }
}

// ─────────────────────────────────────────────
// Countersunk hole: top surface at Z=0, going downward
module cs_hole() {
    union() {
        // countersink taper
        translate([0, 0, -screw_cs_depth])
            cylinder(h = screw_cs_depth + 0.01,
                     r1 = screw_thru_dia / 2,
                     r2 = screw_cs_dia / 2);
        // through hole
        translate([0, 0, -(leaf_thick + 0.01)])
            cylinder(h = leaf_thick - screw_cs_depth + 0.02,
                     r = screw_thru_dia / 2);
    }
}

// ─────────────────────────────────────────────
// Left leaf: plate extends in -X direction
module left_leaf() {
    difference() {
        union() {
            // Flat plate
            translate([-leaf_width, 0, -leaf_thick])
                cube([leaf_width, leaf_length, leaf_thick]);

            // Knuckles with base fills
            for (yc = left_knuckle_y) {
                knuckle_tube(yc);
                knuckle_base_fill(yc);
            }
        }

        // Countersunk screw holes
        for (i = [0 : screw_count - 1]) {
            translate([-leaf_width / 2, screw_y(i), 0])
                cs_hole();
        }

        // Pin bore through all knuckle positions along Y
        translate([0, -1, knuckle_z])
            rotate([-90, 0, 0])
                cylinder(h = pin_length + 2, r = knuckle_ir);
    }
}

// ─────────────────────────────────────────────
// Right leaf: plate extends in +X direction
module right_leaf() {
    difference() {
        union() {
            // Flat plate
            translate([0, 0, -leaf_thick])
                cube([leaf_width, leaf_length, leaf_thick]);

            // Knuckles with base fills
            for (yc = right_knuckle_y) {
                knuckle_tube(yc);
                knuckle_base_fill(yc);
            }
        }

        // Countersunk screw holes
        for (i = [0 : screw_count - 1]) {
            translate([leaf_width / 2, screw_y(i), 0])
                cs_hole();
        }

        // Pin bore
        translate([0, -1, knuckle_z])
            rotate([-90, 0, 0])
                cylinder(h = pin_length + 2, r = knuckle_ir);
    }
}

// ─────────────────────────────────────────────
// Pin: Y from -1 to +31 (1mm overhang each end beyond 0..30)
module pin() {
    translate([0, -1, knuckle_z])
        rotate([-90, 0, 0])
            cylinder(h = pin_length, r = pin_r);
}

// ─────────────────────────────────────────────
// Assembly
color([0.75, 0.75, 0.78], 1.0) left_leaf();
color([0.75, 0.75, 0.78], 1.0) right_leaf();
color([0.85, 0.70, 0.20], 1.0) pin();

// Butt Hinge - 180° open position
// Pin axis along Y, leaves extend in -X and +X directions

$fn = 64;

// Parameters
leaf_width  = 25;
leaf_length = 30;
leaf_thick  = 2;

pin_dia    = 4;
pin_r      = pin_dia / 2;
pin_length = 32;

knuckle_od = 8;
knuckle_or = knuckle_od / 2;
knuckle_id = pin_dia + 0.3;
knuckle_ir = knuckle_id / 2;
knuckle_h  = 6;

// Knuckle Y start positions (each 6mm segment)
// Left leaf  (3 knuckles): segments 0,2,4 → Y start 0, 12, 24
// Right leaf (2 knuckles): segments 1,3   → Y start 6, 18
left_knuckle_y_starts  = [0, 12, 24];
right_knuckle_y_starts = [6, 18];

// Pin axis is at Z = knuckle_or above plate top face (Z=0)
knuckle_z = knuckle_or;

// Screw holes (M3 countersunk)
screw_cs_dia   = 6;
screw_cs_depth = 1;
screw_thru_dia = 3.2;
screw_count    = 3;
screw_pitch    = 8;

function screw_y(i) =
    (leaf_length - (screw_count - 1) * screw_pitch) / 2 + i * screw_pitch;

// ─────────────────────────────────────────────
// Single knuckle: cylinder + web connecting it to the plate
// y0 = Y start of this 6mm segment
module single_knuckle(y0) {
    yc = y0 + knuckle_h / 2;   // centre of knuckle in Y

    // Knuckle tube
    translate([0, yc, knuckle_z])
        rotate([90, 0, 0])
            difference() {
                cylinder(h = knuckle_h, r = knuckle_or, center = true);
                cylinder(h = knuckle_h + 0.1, r = knuckle_ir, center = true);
            }

    // Web / gusset: hull between flat plate rect and knuckle circle,
    // extruded along Y for the length of this knuckle
    translate([0, y0, 0])
        linear_extrude(height = knuckle_h)
            hull() {
                // footprint at plate top (Z=0): thin wide rect
                translate([0, 0])
                    square([knuckle_od, 0.01], center = true);
                // knuckle cross-section at axis height
                translate([0, knuckle_z])
                    circle(r = knuckle_or);
            }
}

// ─────────────────────────────────────────────
// Countersunk hole, opening at Z=0, going into -Z
module cs_hole() {
    // Countersink cone (wide at top, narrow at bottom)
    translate([0, 0, 0.01])
        cylinder(h = screw_cs_depth + 0.01,
                 r1 = screw_cs_dia / 2,
                 r2 = screw_thru_dia / 2,
                 $fn = 32);
    // Through shaft
    translate([0, 0, -(leaf_thick + 0.01)])
        cylinder(h = leaf_thick + screw_cs_depth + 0.02,
                 r = screw_thru_dia / 2,
                 $fn = 32);
}

// ─────────────────────────────────────────────
// Left leaf
module left_leaf() {
    difference() {
        union() {
            // Flat plate (extends in -X)
            translate([-leaf_width, 0, -leaf_thick])
                cube([leaf_width, leaf_length, leaf_thick]);

            // 3 knuckles
            for (y0 = left_knuckle_y_starts)
                single_knuckle(y0);
        }

        // Screw holes on the plate (centred in X over plate)
        for (i = [0 : screw_count - 1])
            translate([-leaf_width / 2, screw_y(i), 0])
                cs_hole();

        // Pin bore along entire Y span
        translate([0, -1, knuckle_z])
            rotate([-90, 0, 0])
                cylinder(h = pin_length + 2, r = knuckle_ir);
    }
}

// ─────────────────────────────────────────────
// Right leaf
module right_leaf() {
    difference() {
        union() {
            // Flat plate (extends in +X)
            translate([0, 0, -leaf_thick])
                cube([leaf_width, leaf_length, leaf_thick]);

            // 2 knuckles
            for (y0 = right_knuckle_y_starts)
                single_knuckle(y0);
        }

        // Screw holes
        for (i = [0 : screw_count - 1])
            translate([leaf_width / 2, screw_y(i), 0])
                cs_hole();

        // Pin bore
        translate([0, -1, knuckle_z])
            rotate([-90, 0, 0])
                cylinder(h = pin_length + 2, r = knuckle_ir);
    }
}

// ─────────────────────────────────────────────
// Pin: Y from -1 to +31 (1mm overhang each end: 0..30 + margins)
module pin() {
    translate([0, -1, knuckle_z])
        rotate([-90, 0, 0])
            cylinder(h = pin_length, r = pin_r);
}

// ─────────────────────────────────────────────
// Assembly
color([0.75, 0.75, 0.78]) left_leaf();
color([0.75, 0.75, 0.78]) right_leaf();
color([0.85, 0.70, 0.20]) pin();