Turbocharger Whistle Fabrication

/* [Global] */

// Resolution of curves
$fn = 80; // [40:5:150]

/* [Dimensions] */

// Maximum outer diameter (including scroll)
total_diameter = 45; // [30:1:60]

// Overall thickness/height
total_height = 18; // [12:1:25]

// Shell thickness
wall_thickness = 1.6; // [1.2:0.1:2.4]

/* [Whistle Tuning] */

// Width of the air nozzle (narrowest point)
nozzle_width = 3.5; // [2.5:0.1:5.0]

// Height of the air nozzle
nozzle_height = 4.0; // [3.0:0.1:6.0]

// Distance from nozzle to splitting edge
fipple_gap = 4.0; // [2.0:0.1:6.0]

/* [Aesthetics] */

// Number of impeller blades
blade_count = 7; // [5:1:12]

/* [Hidden] */
scroll_radius = total_diameter / 2.4;
chamber_r = scroll_radius - wall_thickness;

module impeller() {
    intersection() {
        cylinder(h = total_height/2, r = chamber_r * 0.8);
        union() {
            cylinder(h = total_height/2, r = 2.5); // Center hub
            for(i = [0 : blade_count-1]) {
                rotate([0, 0, i * (360/blade_count)])
                translate([0, -0.5, 0])
                rotate([0, -25, 0]) // Angled for look
                cube([chamber_r * 0.8, 1, total_height/2]);
            }
        }
    }
}

module turbo_whistle() {
    difference() {
        union() {
            // Main Volute Scroll
            for (a = [0 : 10 : 270]) {
                hull() {
                    rotate([0, 0, a])
                        translate([a/360 * 5, 0, 0])
                        cylinder(h = total_height, r = (scroll_radius * 0.7) + (a/360 * (scroll_radius * 0.3)), center = true);
                    
                    rotate([0, 0, a + 10])
                        translate([(a+10)/360 * 5, 0, 0])
                        cylinder(h = total_height, r = (scroll_radius * 0.7) + ((a+10)/360 * (scroll_radius * 0.3)), center = true);
                }
            }
            
            // Tangential Intake (The mouthpiece)
            translate([scroll_radius, -scroll_radius * 1.2, 0])
                rotate([0, 0, 5])
                cube([14, scroll_radius * 1.5, total_height], center = true);
            
            // Decorative Intake Ring
            translate([0, 0, total_height/2])
                cylinder(h = 3, r1 = scroll_radius*0.8, r2 = scroll_radius*0.7);
        }

        // --- INTERNAL CUTOUTS ---
        
        // 1. Resonance Chamber
        cylinder(h = total_height - (wall_thickness*2), r = chamber_r, center = true);

        // 2. Venturi Mouthpiece & Nozzle
        // Tapers from wide to narrow
        translate([scroll_radius, -scroll_radius * 1.1, 0])
            rotate([0, 0, 5])
            hull() {
                // Wide end (mouth)
                translate([0, -scroll_radius*0.5, 0])
                    cube([10, 1, total_height - (wall_thickness*2)], center = true);
                // Narrow end (nozzle)
                translate([0, scroll_radius*0.5, 0])
                    cube([nozzle_width, 1, nozzle_height], center = true);
            }

        // 3. Whistle Window (Air Exit)
        translate([scroll_radius, -fipple_gap, total_height/2 - wall_thickness])
            cube([nozzle_width * 2, fipple_gap * 1.5, wall_thickness * 4], center = true);

        // 4. Fipple (The Sharp Edge)
        // Angled at 45 degrees for printability and sound
        translate([scroll_radius, 0, total_height/2 - wall_thickness])
            rotate([-45, 0, 0])
            cube([nozzle_width * 2, 5, 5], center = true);
            
        // 5. Center Intake Bore (Visible Impeller Hole)
        translate([0, 0, wall_thickness])
            cylinder(h = total_height, r = chamber_r * 0.85);
            
        // 6. Chamfered top edge for 45 deg printability
        translate([0,0,total_height/2])
            difference() {
                cylinder(h=4, r=total_diameter);
                cylinder(h=5, r1=scroll_radius*0.8, r2=scroll_radius*1.2, center=true);
            }
    }
    
    // Add the decorative impeller inside the intake
    translate([0, 0, -total_height/2 + wall_thickness])
        impeller();
}

// Ensure the model is sitting on the ground
translate([0, 0, total_height/2])
    turbo_whistle();