Butterfly-type shim having semi-opened bottom and double sandwich braze

Abstract

Formation of a double sandwich braze joint between the steel body of a bit and a carbide insert tip disposed in a groove formed across the body is facilitated by a butterfly-type shim having a semiopened bottom placed within the groove between surfaces on the bit body defining the groove and adjacent surfaces on the insert tip. The shim has a pair of upstanding spaced side walls and a pair of spaced bottom webs extending between and interconnecting the side walls so as to dispose them between adjacent side surfaces of the bit body groove and insert tip, with lower edges of the shim side walls disposed generally above the bottom webs. The bottom webs rest on the bottom surface of the bit body groove and, in turn, elevate the shim side walls so that their lower edges are spaced above the groove bottom surface. The bottom webs also support the insert tip in spaced relation above the groove bottom surface so as to define a gap which extends across and above the groove bottom surface, below the insert tip bottom surface and the shim side wall lower edges, and between the opposite side surfaces of the bit body groove. The gap will allow relatively unrestricted molten braze alloy flow across the groove bottom surface to facilitate setting up of capillary flow upwardly along adjacent surfaces of the bit body and insert tip on opposite sides of the shim side walls to produce the braze joint.