a method for making an earth boring drill bit which includes an outer shell having an external surface adapted to carry cutting elements and a unitary shank and bit core which is fitted into the outer shell . the shell and bit core are threadably engaged with one another or are interferingly engaged . the shell and bit core may be welded , secured with brazing alloys or with high temperature adhesives . in one embodiment , a ridge formed on the shank is received in a groove formed on an interior surface of the shell to prevent relative rotational movement of the shank and shell during drilling . in another embodiment , the shell is formed using matrix infiltration techniques . after the shell is formed , it is heated to braze cutters thereto . while still hot from the brazing process , the shell and shank are fitted together . after cooling the shell contracts to form heat shrink connection between the shell and the shank .