Abstract: An electrode used as a tool in an electrochemical machining process to generate raised areas or ridges in the walls of a predrilled hole in an electrically conductive workpiece has an electrically conductive cylinder partially coated with an electrically insulating material in a pattern defining the raised areas to be formed. The pattern may comprise a plurality of spaced apart rings. An electrochemical machining method of drilling bulbs in the walls of a predrilled hole uses the electrode of the invention to greatly increase process efficiency.

Abstract: A magnet pole piece assembly has first and second pole pieces and at least one support member. The pole pieces have longitudinally aligned and facing surface recesses. The support member has a central segment and first and second end segments abuttingly and metallurgically attached to the central segment. The first and second end segments are positioned within a corresponding surface recess of the first and second pole piece and are abuttingly and metallurgically attached to the corresponding pole piece. An open magnet adds main coils to the magnet pole piece assembly.