We report the advances made in electrochemical machining of access holes through sheet
metal during FY2005. The cutting tool underwent a major engineering re-design to
accommodate an oblong cut with parallel sides (1.5” spacing) on a surface of arbitrary
curvature. The solid cathode was replaced by an array of separately movable steel pins,
allowing the tool to conform to the surface shape of the work piece prior to beginning
cutting. Preliminary cuts through a hardened steel drum (0.04 inch thickness) were
successfully completed at a low current (50A) but the current efficiency of the cutting
process was poor (