Abstract: Formation of a continuous double sandwich braze joint between a bit body of a conical bit and a carbide insert tip disposed in a cylindrical recess formed in a forward end of the bit body is facilitated by a cylindrical shim. In one form, the shim is a cylindrical sleeve having an annular sidewall with opposite forward and rearward open ends. The insert tip is received through the forward open end of the sleeve. Also, a multiplicity of perforations are defined in spaced apart relation through the sidewall and uniformly distributed thereabout. The multi-perforated sleeve is disposed within the bit body recess and between its interior and the exterior of a cylindrical base of the insert tip such that the multiplicity of perforations defined in the sleeve sidewall provide a multiplicity of spaces extending between the bit body and insert tip for receiving braze therethrough. In an alternative form, the shim is a cylindrical basket having a sidewall and endwall.

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 an array of perforations defined through its bottom wall and side walls and generally across a mid-section region of the shim. The shim also has opposite end regions where the bottom wall and side walls are solid and free of perforations. The shim side walls are disposed between the side surfaces of the bit body and insert tip and the shim bottom wall is disposed between the bottom surfaces of the bit body and insert tip such that the shim mid-section region containing the perforations is disposed adjacent central regions of the bit body and insert tip and the shim solid perforation-free opposite end regions are disposed adjacent opoposite end regions of the bit body and insert tip.