A self-aligning coupler for aligning superposed surfaces during coupling parts to each other, wherein the self-aligning coupler comprises: a circular and semi-spherical base formed on a first surface of the superposed surfaces; a through-bore extending perpendicularly through the circular and semi-spherical base; a fastening element perpendicularly passing through the through-bore of the circular and semi-spherical base, its fastening element comprising a secondary end which is inserted in a second surface of the superposed surfaces which is opposed to the first surface; the self-aligning coupler being characterized by the fact that also comprises: at least a semi-spherical insert including a semi-spherical portion, having the same curvature as the circular and semi-spherical base, facing the circular and semi-spherical base concentrically surrounding the fastening element, and a flat portion opposite to the semi-spherical portion and facing a parallel insert, and at least one parallel insert formed by flat portion parallel to each other and concentrically surrounding the fastening element, the parallel insert positioned between the flat portion of the semi-spherical insert and the second surface of the superposed surfaces, wherein the semi-spherical portion of said semi-spherical insert cooperatively engages the circular and semi-spherical base to self-align the superposed first and second surfaces in response to tightening the fastening element. a circular and semi-spherical base formed on a first surface of the superposed surfaces; a through-bore extending perpendicularly through the circular and semi-spherical base; a fastening element perpendicularly passing through the through-bore of the circular and semi-spherical base, its fastening element comprising a secondary end which is inserted in a second surface of the superposed surfaces which is opposed to the first surface; the self-aligning coupler being characterized by the fact that also comprises: at least a semi-spherical insert including a semi-spherical portion, having the same curvature as the circular and semi-spherical base, facing the circular and semi-spherical base concentrically surrounding the fastening element, and a flat portion opposite to the semi-spherical portion and facing a parallel insert, and at least one parallel insert formed by flat portion parallel to each other and concentrically surrounding the fastening element, the parallel insert positioned between the flat portion of the semi-spherical insert and the second surface of the superposed surfaces, wherein the semi-spherical portion of said semi-spherical insert cooperatively engages the circular and semi-spherical base to self-align the superposed first and second surfaces in response to tightening the fastening element. at least a semi-spherical insert including a semi-spherical portion, having the same curvature as the circular and semi-spherical base, facing the circular and semi-spherical base concentrically surrounding the fastening element, and a flat portion opposite to the semi-spherical portion and facing a parallel insert, and at least one parallel insert formed by flat portion parallel to each other and concentrically surrounding the fastening element, the parallel insert positioned between the flat portion of the semi-spherical insert and the second surface of the superposed surfaces, wherein the semi-spherical portion of said semi-spherical insert cooperatively engages the circular and semi-spherical base to self-align the superposed first and second surfaces in response to tightening the fastening element.