CIRCLE_ROUNDS=36;

// Cylinder Block
difference() {
    // Block
    translate([-8, -8, 0])
    cube([16, 16, 11]);

    // Piston bearing
    translate([0, 0, 0])
    cylinder(h=11, d=10, $fn=CIRCLE_ROUNDS);

    // Block Head Screw Holes
    translate([6, 6, 0])
    cylinder(h=11, d=1, $fn=CIRCLE_ROUNDS);
    translate([-6, 6, 0])
    cylinder(h=11, d=1, $fn=CIRCLE_ROUNDS);
    translate([6, -6, 0])
    cylinder(h=11, d=1, $fn=CIRCLE_ROUNDS);
    translate([-6, -6, 0])
    cylinder(h=11, d=1, $fn=CIRCLE_ROUNDS);
}

// Piston
difference() {
    // Main Cylinder
    cylinder(h=10, d=10, $fn=CIRCLE_ROUNDS);
    
    // Main cutout
    rotate([90, 0, 0])
    translate([0, 1, -5]) {
        cylinder(h=10, d=8, $fn=CIRCLE_ROUNDS);
    }
    translate([-4, -3, 0])
    cube([8, 6, 1]);
    
    // Tapering cutout on the bottom
    difference() {
        cylinder(h=5, d=10, $fn=CIRCLE_ROUNDS);
        cylinder(h=5, d=9, $fn=CIRCLE_ROUNDS);
    }
    
    // gudgeon pin hole
    rotate([0, 90, 0])
    translate([-2, 0, -5])
    cylinder(h=10, d=2, $fn=CIRCLE_ROUNDS);
}

// Gudgeon pin
difference() {
    rotate([0, 90, 0])
    translate([-2, 0, -4.5])
    cylinder(h=9, d=2, $fn=CIRCLE_ROUNDS);
    
    rotate([0, 90, 0])
    translate([-2, 0, -4.5])
    cylinder(h=9, d=1.5, $fn=CIRCLE_ROUNDS);
}

// Rod
difference() {
    union() {
        // rod shaft
        translate([-1, -1.5, -13])
        cube([2, 3, 15]);

        // rod pin hole
        rotate([90, 0, 90])
        translate([0, 2, -2])
        cylinder(h=4, d=4, $fn=CIRCLE_ROUNDS);

        // crankshaft hole
        rotate([90, 0, 90])
        translate([0, -13, -2])
        cylinder(h=4, d=3, $fn=CIRCLE_ROUNDS);
    }
    
    // gudgeon pin cutout
    rotate([0, 90, 0])
    translate([-2, 0, -4.5])
    cylinder(h=9, d=2, $fn=CIRCLE_ROUNDS);

    // crankshaft cutout
    rotate([0, 90, 0])
    translate([13, 0, -2])
    cylinder(h=4, d=2, $fn=CIRCLE_ROUNDS);
}