OpenSCAD source code: Adapter from pole to six-gallon can lid to make a bird feeder platform

Can Lid Platform Feeder Mount.scad

// Adapter from steel pole to 5 gallon plastic can lid
// Turns the lid into a improvised platform feeder
// Ed Nisley - KE4ZNU - 2018-11

Layout = "Build";     // Show Build

ThreadThick = 0.25;
ThreadWidth = 0.40;

HoleWindage = 0.2;

function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

Protrusion = 0.1;           // make holes end cleanly

// Sizes

ID = 0;
OD = 1;
LENGTH = 2;

Wall = 10;                      // minimum thickness or width for anything

Boss = [15,50,9];               // central boss on lie
Flange = [50,110,Boss[LENGTH] + Wall];

echo(Boss);
echo(Flange);

Pole = [(23.5 + 4*HoleWindage),26,45];            // small end of steel pole

Screw = [5.0,8.0,25.0];         // 5 mm or 10-32
ScrewOC = 80;                   // lid mounting screws
NumScrews = 3;

NumSides = NumScrews*2*4;
$fn = NumSides;

//----------------------
// Useful routines

module PolyCyl(Dia,Height,ForceSides=0) {           // based on nophead's polyholes

  Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);
  FixDia = Dia / cos(180/Sides);
  cylinder(r=(FixDia + HoleWindage)/2,h=Height,$fn=Sides);
}

//----------------------
// Build it

module Bracket() {

  difference() {

    union() {
      rotate(180/(NumSides/2)) {
        cylinder(d=Flange[OD],h=Flange[LENGTH],$fn=NumSides/2);   // fewer sides is OK
        cylinder(d=Pole[OD] + 2*Wall,h=Pole[LENGTH] + Flange[LENGTH],$fn=NumSides/2);
      }
    }

    translate([0,0,-Protrusion])
      rotate(180/NumSides)
        cylinder(d=Boss[OD],h=Boss[LENGTH] + Protrusion,$fn=NumSides);

    translate([0,0,-Protrusion])
      rotate(180/NumSides)
        cylinder(d=Pole[ID],h=2*(Pole[LENGTH] + Flange[LENGTH]),$fn=NumSides);

    for (i=[0:NumScrews-1])
      rotate(i*(360/NumScrews))
        translate([ScrewOC/2,0,-Protrusion])
          PolyCyl(Screw[ID],2*Flange[LENGTH],6);
  }

}

module Support() {

  NumRibs = NumSides/2;
  Rib = [0.95*(Boss[OD] - Pole[ID])/2,2*ThreadWidth,Boss[LENGTH] - ThreadThick];

  color("Yellow") {
    for (i=[0:NumRibs-1]) {
      a = i*360/NumRibs;
      rotate(a)
        translate([Pole[ID]/2 + Rib.x/2,0,Rib.z/2])
          cube(Rib,center=true);
    }
    rotate(180/NumSides)
      difference() {
        cylinder(d=Pole[ID] + 10*ThreadWidth,h=1*ThreadThick,$fn=NumSides);
        translate([0,0,-Protrusion])
          cylinder(d=Pole[ID],h=Rib.z + 2*Protrusion,$fn=NumSides);
      }
  }

}

if (Layout == "Show")
  Bracket();

if (Layout == "Build") {
  Bracket();
  Support();
}

More details on my blog at https://wp.me/poZKh-7SG