// Screw covers

$fn = 16;

// The hollow bit that goes in (this one for getting the size right
module test_shaft() {
  linear_extrude(height=5)
  difference() {
    shape();
    scale([0.9, 0.9]) shape();
  }
}
// Actual shaft
module shaft() {
  difference() {
    union() {
      linear_extrude(height=10)
      difference() {
        shape();
        scale([0.85, 0.85]) shape();
      };
      prongs();
    };
    //ubeam();
  };
    
}

// The cutout for the springy prongs to sit on
module ubeam() {
  translate([-1, -10, 1.35])
  difference() {
    cube([4, 20, 5]);
    translate([0.5, -1, 0.5]) cube([3, 25, 5]);
  }
}

// The prongs to hold it in
module prongs () {
  union() {
    translate([-0.5, -5.25, 2.75]) rotate([0, 90, 0])
      difference() {
        cylinder(3, r=1);
        translate([-1, 0, -0.1]) cube([2, 2, 4]);
      };
    translate([2.5, 5.25, 2.75]) rotate([0, 90, 180])
      difference() {
        cylinder(3, r=1);
        translate([-1, 0, -0.1]) cube([2, 2, 4]);
      };
  }
}

// The top bit to stop water getting in
module cap() {
  linear_extrude(height=1)
  scale([1.5, 1.5]) shape();
}

// The 2d shape of the hole
module shape() {
  width = 11.75;
  height = 11.75;
  translate([-width / 2, -height / 2, 0])
  difference() {
    square([width, height]);
    union() {
      translate([width - (sqrt(2) / 2), 0, 0]) rotate([0, 0, -45]) square([1, 1]);
      translate([width - (sqrt(2) / 2), height, 0]) rotate([0, 0, -45]) square([1, 1]);
      translate([0 - (sqrt(24.5) / 2), height, 0]) rotate([0, 0, -45]) square([3.5, 3.5]);
      translate([0 - (sqrt(24.5) / 2), 0, 0]) rotate([0, 0, -45]) square([3.5, 3.5]);
    };
  }
}

// test_shaft();
union() {
  shaft();
  cap();
}