bare/claude-opus-4-5 / tier-3-butt-hinge

```openscad
// Butt Hinge - Furniture Small Size
// Three parts: Left leaf, Right leaf, Pin

// Parameters
leaf_length = 30;      // Y direction (along hinge axis)
leaf_width = 25;       // X direction (opening direction)
leaf_thickness = 2;    // Z direction

pin_diameter = 4;
pin_length = 32;
pin_clearance = 0.3;

knuckle_outer_diameter = 8;
knuckle_inner_diameter = pin_diameter + pin_clearance;
knuckle_height = 6;    // 30mm / 5 = 6mm each
knuckle_count = 5;

// Countersunk hole parameters
hole_diameter = 3.2;
countersink_diameter = 6;
countersink_depth = 1;
hole_spacing = 8;
hole_offset_from_knuckle = 12.5;  // Center of holes from knuckle edge

$fn = 64;

// Module for countersunk hole
module countersunk_hole() {
    union() {
        // Through hole
        cylinder(h = leaf_thickness + 1, d = hole_diameter, center = true);
        // Countersink (on top surface, z = leaf_thickness/2)
        translate([0, 0, leaf_thickness/2 - countersink_depth/2 + 0.01])
            cylinder(h = countersink_depth, d1 = hole_diameter, d2 = countersink_diameter, center = true);
    }
}

// Module for knuckle (half cylinder attached to leaf)
module knuckle(is_left) {
    difference() {
        // Outer cylinder
        rotate([-90, 0, 0])
            cylinder(h = knuckle_height, d = knuckle_outer_diameter, center = false);
        // Inner hole for pin
        rotate([-90, 0, 0])
            translate([0, 0, -0.1])
                cylinder(h = knuckle_height + 0.2, d = knuckle_inner_diameter, center = false);
    }
}

// Module for leaf plate (without knuckles)
module leaf_plate() {
    // Plate positioned so that the edge at x=0 aligns with knuckle center
    // and extends in -x direction for left leaf (will be mirrored for right)
    translate([-leaf_width, 0, -leaf_thickness/2])
        cube([leaf_width, leaf_length, leaf_thickness]);
}

// Module for left leaf (3 knuckles: positions 0, 2, 4 - i.e., outer two + center)
module left_leaf() {
    knuckle_radius = knuckle_outer_diameter / 2;
    
    difference() {
        union() {
            // Main plate - extends in -X direction
            // Plate top surface at z = knuckle center height - leaf_thickness/2 + knuckle_radius
            // For 180° open, both plates should be on same plane
            // Knuckle center is at z=0, so plate surface should be at z = leaf_thickness/2
            // But we want flat surfaces coplanar, so plate from z=0 to z=-leaf_thickness
            translate([-leaf_width, 0, -leaf_thickness])
                cube([leaf_width, leaf_length, leaf_thickness]);
            
            // Knuckles at positions 0, 2, 4 (left leaf gets 1st, 3rd, 5th)
            for (i = [0, 2, 4]) {
                translate([0, i * knuckle_height, 0])
                    knuckle(true);
            }
        }
        
        // Countersunk holes (3 holes along Y axis)
        for (i = [-1, 0, 1]) {
            translate([-hole_offset_from_knuckle, leaf_length/2 + i * hole_spacing, -leaf_thickness/2])
                countersunk_hole();
        }
    }
}

// Module for right leaf (2 knuckles: positions 1, 3 - middle two)
module right_leaf() {
    difference() {
        union() {
            // Main plate - extends in +X direction (mirrored)
            translate([0, 0, -leaf_thickness])
                cube([leaf_width, leaf_length, leaf_thickness]);
            
            // Knuckles at positions 1, 3 (right leaf gets 2nd, 4th)
            for (i = [1, 3]) {
                translate([0, i * knuckle_height, 0])
                    knuckle(false);
            }
        }
        
        // Countersunk holes (3 holes along Y axis)
        for (i = [-1, 0, 1]) {
            translate([hole_offset_from_knuckle, leaf_length/2 + i * hole_spacing, -leaf_thickness/2])
                countersunk_hole();
        }
    }
}

// Module for pin
module pin() {
    rotate([-90, 0, 0])
        translate([0, 0, -1])  // Start 1mm before knuckles
            cylinder(h = pin_length, d = pin_diameter, center = false);
}

// Assembly - 180° open position
// Left leaf (red)
color("DarkGray")
    left_leaf();

// Right leaf (blue)  
color("Gray")
    right_leaf();

// Pin (silver)
color("Silver")
    pin();
```