Parametric car rim

// A car-style rim: a barrel with a flange at each edge and a closed face disc at one end,
// with a centre bore, lug holes on a bolt circle and round vents. No spokes.

/* [Size] */
// Diameter of the rim barrel, the seat the tyre grips. Match the tyre's rim_diameter.
rim_diameter = 34; // [10:1:160]
// Width across the rim, bead to bead. Match the tyre's width.
width = 22; // [4:1:80]

/* [Face] */
// Thickness of the closed face disc.
face_thickness = 4; // [2:0.5:10]
// Centre bore for the axle.
bore_diameter = 8; // [2:1:40]
// Lug holes around the bore. Zero leaves a plain face.
lug_count = 5; // [0:1:10]
// Bolt circle diameter the lug holes sit on.
lug_circle = 18; // [6:1:120]
// Diameter of each lug hole.
lug_hole = 4.6; // [2:0.1:12]
// Round vents in the face. Zero closes the face.
vent_count = 5; // [0:1:16]
// Diameter of each vent.
vent_diameter = 5; // [0:0.5:30]

/* [Shape] */
// Wall thickness of the barrel.
wall = 2.4; // [1:0.1:6]
// How far the flanges stand proud of the barrel.
flange = 1.2; // [0:0.1:4]
// Facets around the rim. More is smoother and slower.
smoothness = 96; // [24:8:192]

/* [Colour] */
// Colour the rim is shown in. Display only, the STL carries no colour.
color_rim = "Silver"; // [Silver, Gainsboro, White, DimGray, Black, SlateGray, FireBrick, SteelBlue, ForestGreen, Goldenrod]

/* [Hidden] */
rim_radius = rim_diameter / 2;
half_width = width / 2;
flange_height = 1.4;
// Both hole circles are clamped inside the barrel wall, so a small rim pulls the holes
// inward instead of breaking through the side.
lug_radius = min(lug_circle / 2, rim_radius - wall - lug_hole / 2 - 1);
vent_radius_pos = min(rim_radius - wall - vent_diameter / 2 - 0.5,
                      lug_radius + lug_hole / 2 + vent_diameter / 2 + 0.8);

module barrel() {
  difference() {
    cylinder(h = width, r = rim_radius, center = true, $fn = smoothness);
    cylinder(h = width + 1, r = rim_radius - wall, center = true, $fn = smoothness);
  }
}

module flanges() {
  for (z = [-half_width, half_width - flange_height])
    translate([0, 0, z])
      difference() {
        cylinder(h = flange_height, r = rim_radius + flange, $fn = smoothness);
        translate([0, 0, -0.5])
          cylinder(h = flange_height + 1, r = rim_radius - wall, $fn = smoothness);
      }
}

// The face sits at one end, the way a car rim is dished, leaving the barrel open behind it.
module face() {
  translate([0, 0, half_width - face_thickness])
    difference() {
      cylinder(h = face_thickness, r = rim_radius - wall / 2, $fn = smoothness);
      translate([0, 0, -0.5])
        cylinder(h = face_thickness + 1, d = bore_diameter, $fn = smoothness);
      if (lug_count > 0)
        for (i = [0 : lug_count - 1])
          rotate([0, 0, i * 360 / lug_count])
            translate([lug_radius, 0, -0.5])
              cylinder(h = face_thickness + 1, d = lug_hole, $fn = 32);
      // Vents sit half a pitch from the lugs, so equal counts interleave.
      if (vent_count > 0 && vent_diameter > 0)
        for (i = [0 : vent_count - 1])
          rotate([0, 0, (i + 0.5) * 360 / vent_count])
            translate([vent_radius_pos, 0, -0.5])
              cylinder(h = face_thickness + 1, d = vent_diameter, $fn = 32);
    }
}

module rim() {
  union() {
    barrel();
    flanges();
    face();
  }
}

color(color_rim) rim();