an ultrasonic welding assembly is disclosed . the assembly includes an ultrasonic welder having nodal horn support for improving transmission of transducer energy to the weld comprising an acoustical tool having a horn ; a weld tip on the end of said horn ; and at least two nodal mounts which are in contact with and axially and radially support said horn . the horn self - aligns in housing by sitting a housing - key within a keyway in the horn . the weld tip self aligns by sitting the keyed tip in a keyway of the horn .