Design and Implementation of a Closed-Loop CNC Engraving Machine Using Arduino-Based PID Control

A This paper presents the design and implementation of a low-cost desktop CNC engraving system enhanced with a closed-loop control mechanism using Arduino microcontrollers. The system addresses key limitations associated with traditional open-loop configurations, including position loss, limited motion accuracy, and inadequate response to dynamic disturbances. A dual-microcontroller architecture was adopted, where an Arduino Uno serves as the master for user interface and G-code parsing, while an Arduino Mega 2560 acts as the slave for real-time motion control. Closed-loop regulation was achieved through encoder-based feedback on the X and Y axes, driven by DC servo motors, while the Z axis employed a stepper motor. A digital PID controller was implemented to improve motion stability and tracking performance. A wireless PS2 controller and LCD display were integrated to support user interaction and manual positioning. Experimental evaluation included PID tuning, calibration of encoder-to-displacement mapping, and dynamic response assessment. The results confirmed notable improvements in positional accuracy, repeatability, and responsiveness over the open-loop baseline. The study demonstrates the feasibility of building accessible, precise, and responsive CNC systems using open-source hardware, contributing to affordable digital fabrication technologies for education and small-scale prototyping.