Abstract: A machine is provided for assemblying the elements of a truss and fastening them together in a positive manner. A supporting table is made up of channel elements which have platforms thereon which are movable upwardly and are adjustable in a horizontal plane toward and away from the center of the table. A carriage runs upon spaced tracks to locate pressure plates which are mounted on a pair of like C-frames which are adjustable toward and away from each other so as to be effective for trusses of different heights. The pressure plates are moved toward each other and apply a substantial pressure for inserting a multiplicity of nails of a nail plate into the areas in which the members of the truss are to be secured together. This provides a truss of exact shape and dimension which is positively secured together and, where necessary, is provided with a rectangular opening in which a heating and/or cooling duct is supported.