Nowadays machining using hard materials and complex shapes has become a necessity, therefore to overcome this problem non-conventional machining has been developed, one of which is electrochemical machining (ECM). Previous studies have not been much discussed about the fabrication process on 1100 aluminum using perforated brass tools. This study aims to analyze the effect of stress on the MRR value, overcut and taper on the results of electrochemical machining (ECM) machining, especially masking and non masking workpieces. The aluminum 1100 workpiece is cut to 80 x 35 x 0.5 mm, then separated into two parts, masking and non masking workpieces. Pattern size masking workpieces are made the same as perforated brass tools. In the machining process, the specimen is placed in the vise that is in the sink tub in an upright position with the electrode tool. The size of the tool gap with the workpiece is 0,5 mm. Enter the electrolyte solution with a concentration level of 15% into the trough. Machining is carried out using variations of voltage 7, 10, 13 volt with a flow rate of 2.5 lpm and a 144 second machining time. In this study, the results show that the greater the voltage supplied at machining, the flow of current, the value of MRR, overcut and taper will increase. The average current of the masking workpiece is 26,15 amperes while in non masking it is 24,45 amperes. For the highest MRR values on masking workpieces 6.12 x10-7 mm3/s, on non masking objects 22.508 x10-7 mm3/s. The highest value of overcut on the masking workpiece is 1,571 mm and non masking workpiece 2,038 mm. The highest value for masking workpiece is 44,038o and non masking workpiece is 52,388o.