Abstract: A portable seam locking device which is mountable on a portable hand tool. The device provides a support anvil for supporting the flanges which are to be folded and a hammer for bending one flange with respect to the other to perform the required fold over seam joint between two metal flanges. The hammer is mounted in the housing of the device for oscillating movement with respect to the anvil. The head of the anvil is formed with a small ridge on its inner surface which serves to form a series of crimps in the joint which prevent longitudinal slipping between the components of the joint.

Abstract: A sheet metal structure having two panels of substantially the same cross section connected to one another by a lap joint at their outer ends. Each panel has at least one major U-shaped section which has a base wall and a pair of oppositely disposed side walls. The base wall is formed with a plurality of minor U-shaped longitudinally extending ribs which form a plurality of alternately disposed minor crests and velleys. The major U-shaped sections and the minor ribs of the panels nest with one another at the lap joint. A spacer panel is provided for spacing the nesting ends from one another to facilitate the rigid securing of the ends. The spacer panel has a body portion formed with a plurality of spacer lugs at one edge thereof which project outwardly from the body portion in a spaced relationship. The lugs have a thickness substantially equal to the thickness of the panels which are to be joined.