Abstract: The specification discloses a method and apparatus for combining high speed horizontal and high speed vertical continuous mixing of sand and binder ingredients for mold making purposes. Sand supplied by a hopper assembly and liquid binder ingredients supplied by injection assemblies are fed into the rearward ends of a pair of side-by-side, horizontally extending cylindrical mixing chambers. They are rapidly mixed and conveyed forwardly by blade assemblies which extend centrally through the horizontal mixing chambers and are rotated at from about 300 rpm to about 1500 rpm. The mixtures are then discharged into a vertically extending cylindrical mixing chamber where they are rapidly mixed by a blade assembly which extends centrally through the vertical mixing chamber and is rotated at from about 300 rpm to about 800 rpm. The final mixture is then discharged from the vertical mixing chamber downwardly into a mold box.