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

```openscad
// 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();
```