EDM Control using Multiplier and Axis Selector with MPG

Abstract

This paper presents the design and implementation of an EDM (Electrical Discharge Machining) control interface using a Manual Pulse Generator (MPG), multiplier selector, and axis selector based on the PIC18F258 microcontroller. The proposed system enables precise manual positioning of EDM machine axes during setup and machining operations. The MPG handwheel generates quadrature signals which are decoded by the PIC18F258 operating at 40 MHz. The controller processes operator selected movement multipliers (×1, ×10, ×100) and allows selection of a single axis at a time for accurate positioning control. The hardware consists of a regulated 5 V power supply using a DF005M bridge rectifier and LM7805 voltage regulator, a 16×2 LCD display for user feedback, axis and multiplier selection switches, and an interface to a DS8660 stepper motor driver controlling an 86SC85D stepper motor. The LCD continuously displays the selected axis, multiplier value, pulse count, and movement direction. The complete system schematic and PCB were designed using KiCad EDA. Firmware was developed using MPLAB X IDE v6.25 and XC8 Compiler v3.10. Experimental testing verified correct quadrature decoding, accurate multiplier operation, reliable axis selection, and stable motor control. The proposed design provides a low-cost, compact, and user-friendly EDM positioning controller suitable for educational, industrial, and research applications.

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