THE ECM TECHNIQUES CURRENTLY USED FOR PRODUCING SMALL DEEP HOLES ARE SHAPED TUBE ELECTROLYTIC MACHINING (STEM), CAPILLARY DRILLING (CD), AND ELECTROSTREAM DRILLING (ESD). THESE PROCESSES USE A STRONG ACID ELECTROLYTE AND CREATE STRESS FREE, METALLURGICALLY UNDAMAGED MICROHOLES OF HIGH LENGTH TO DIAMETER RATIO (UP TO 300:1). COMPLEX CLOSED LOOP CONTROL OF ACID FLOW AND PRESSURE, CONJOINT WITH PRECISE CONTROL OF OTHER MACHINING PARAMETERS, HAS BEEN ACHIEVED. WITH CD AND ESD, DRILL BREAKAGE OR CHIPPING OF THE GLASS TUBES WHICH FORM THE DRILL FACE IS A COMMON PROBLEM CAUSING SCRAP. A MEANS OF MONITORING DRILLING CURRENT AND HIGH FREQUENCY EMISSION DURING THE PROCESS HAS BEEN DEVELOPED. THIS SYSTEM CAN SUCCESSFULLY DETECT MORE THAN 95% OF DRILL BREAKAGE WITH A MINIMUM OF FALSE ALARMS.