A method of performing friction stir welding is provided herein. More specifically, traditional friction stir welding requires a rotatable head that is forced against a plurality of work pieces to bond the same. The rotational and normal forces generated by the friction stir welding tool are generally reacted by a backing plate, anvil, mandrel or other mechanisms, such hardware are subject to the applied forces and are often supported with additional internal supports. Conversely, a method of performing a friction stir weld is described that omits the need for such a backing member and internal supports as it is performed using a self reacting pin tool.