module roue_dentee(diametre, nb_dents, largeur_dent) {
    dent_angle = 360/nb_dents;
    cylinder(h=5, r=diametre/2, center=true);
    for(i=[0 : nb_dents-1])   {
        rotate([0,0,i*dent_angle])
        translate([diametre/2,0,0])
        cube([largeur_dent,5,5],center=true);
    }
}

roue_dentee(50,20,2);