$fn = 180;

wheel_dia = 100;
wheel_width = 10;
wheel_height = 5;
wheel_height2 = 10;
tube_outer_dia = 16;

shaft_dia = 25;
shaft_length = 25;

wire_dia = 3.5;

delta = 0.01;

difference() {
    union() {
        difference() {
            cylinder(d = wheel_dia, 
                    h = wheel_height,
                    center = true);
            
            cylinder(d = wheel_dia - 2*wheel_width, 
                h = wheel_height + delta, 
                center = true);
        }

 
        cube([wheel_width, wheel_dia, wheel_height], 
              center = true);
        
        translate([0, 0, -wheel_height/2 + wheel_height2/2])
        cube([wheel_dia, wheel_width, wheel_height2], 
              center = true);

        translate([0, 0, shaft_length/2 - wheel_height/2])
            cylinder(d = shaft_dia, h=shaft_length, center = true);
    }
    
    translate([0, 0, shaft_length/2 - wheel_height/2])
        cylinder(d = tube_outer_dia, 
                h=shaft_length + delta, 
                center=true);
    
    
    translate([0, 0, wheel_height/2])
        rotate([0,90, 90])
            cylinder(d = wire_dia, h = wheel_dia + delta, center=true);
    
    translate([0, 0, wheel_height/2 + wheel_height2/2])
        rotate([0,90, 0])
            cylinder(d = wire_dia, h = wheel_dia + delta, center=true); 
}