bare-low/claude-opus-4-7 / tier-3-butt-hinge

```openscad
// Butt hinge - opened 180 degrees
// Pin axis along Y, leaves in XY plane (Z=0 mid-plane of leaves)

$fn = 64;

leaf_w = 25;     // x extent of leaf (from knuckle edge outward)
leaf_h = 30;     // y extent (along pin axis)
leaf_t = 2;      // thickness
knuckle_od = 8;
knuckle_id = 4.6;
pin_d = 4;
pin_len = 32;
seg = 6;         // each knuckle segment length (30/5)

// Screw holes: 3 per leaf, pitch 8mm along Y, centered on leaf
screw_pitch = 8;
screw_through_d = 3.2;
csk_d = 6;
csk_depth = 1;

// Leaf: flat plate from x=knuckle_od/2 outward (no, plate extends from x=0 to x=leaf_w on right, mirrored on left)
// But plate must connect to knuckle. Plate centered on z=0, thickness leaf_t.
// Plate spans x in [knuckle_od/2 ... knuckle_od/2 + leaf_w] roughly, but knuckle radius 4 so plate starts at x=4.
// We'll make plate from x=0 to x=leaf_w (the part inside knuckle gets unioned with knuckle).

module leaf_plate(side) {
    // side = +1 (right, x>0) or -1 (left, x<0)
    // plate: width leaf_w in x, height leaf_h in y, thickness leaf_t in z
    // Screw hole center: place 3 holes along y, centered, at x near far end
    screw_x = side * (leaf_w - 5); // 5mm from outer edge
    difference() {
        translate([side > 0 ? 0 : -leaf_w, -leaf_h/2, -leaf_t/2])
            cube([leaf_w, leaf_h, leaf_t]);
        // screw holes (countersunk from top, +Z face)
        for (i = [-1, 0, 1]) {
            translate([screw_x, i*screw_pitch, 0]) {
                // through hole
                translate([0,0,-leaf_t/2 - 0.1])
                    cylinder(d=screw_through_d, h=leaf_t + 0.2);
                // countersink (taper) on top face
                translate([0,0,leaf_t/2 - csk_depth])
                    cylinder(d1=screw_through_d, d2=csk_d, h=csk_depth + 0.01);
            }
        }
    }
}

module knuckle_seg(y0) {
    translate([0, y0, 0])
        rotate([-90,0,0])
            difference() {
                cylinder(d=knuckle_od, h=seg);
                translate([0,0,-0.1])
                    cylinder(d=knuckle_id, h=seg+0.2);
            }
}

// Left leaf: knuckles at segments 0,2,4 (outer two + center)
module left_leaf() {
    color("silver") {
        union() {
            leaf_plate(-1);
            // segments y in [-15,-9], [-3,3], [9,15] => y0 = -15, -3, 9
            knuckle_seg(-15);
            knuckle_seg(-3);
            knuckle_seg(9);
        }
    }
}

// Right leaf: knuckles at segments 1,3 => y0 = -9, 3
module right_leaf() {
    color("silver") {
        union() {
            leaf_plate(+1);
            knuckle_seg(-9);
            knuckle_seg(3);
        }
    }
}

module pin() {
    color("gold")
        translate([0, -pin_len/2, 0])
            rotate([-90,0,0])
                cylinder(d=pin_d, h=pin_len);
}

left_leaf();
right_leaf();
pin();
```