//CC BY NC 4.0
// Attribution :
// - Luc Hanneuse, author, conception, realisation, OpenScad design, optimisation for 3D printing & documentation.
// - Florent Lemaire for OpenScad help
// AgriLab, http://agrilab.unilasalle.fr/ , Innovation Center & FabLab Collaborative innovation for Agriculture
// Name : Bpex, Boitier Parametrique Extérieur
// Contact for other licences or commercial usage : agrilab@unilasalle.fr
// Inspired by the Stevenson screen

$fn = 100;

// unit in mm
shell = 0.4 * 4; // multiple of the printer's nozzel size, here 0.4
sizeBase = 40; // bottom radius
sizeTop = 30; // top radius
pinInsideSize = 3.2; // Thread diameter
numberOfPin = 3; // number of thread
height= 20; // height of each element

difference() {
cylinder(r1=sizeBase, r2=sizeTop, h=height, center=true);
cylinder(r1=sizeBase-shell, r2=sizeTop-shell, h=height, center=true);
	for (p = [0:numberOfPin-1]) {
		rotate([0,0,p*360/numberOfPin]) {
		    translate([sizeTop,0,0]) {
		            cylinder(r=pinInsideSize, h=height, center=true);
		    }
		}
	}
}

for (p = [0:numberOfPin-1]) {
	rotate([0,0,p*360/numberOfPin]) {
	    translate([sizeTop,0,0]) {difference() {
	            cylinder(r=pinInsideSize+shell, h=height, center=true);
	            cylinder(r=pinInsideSize, h=height, center=true);
	        }
	    }
	}
}