Appreciation of CNC Technology Through Machine Tool Upgrading by an Open Controller

Abstract Upgrading of a tabletop two-axis CNC lathe is presented in sufficient technical detail in the light of embedding computer numerical control (CNC) of machine tools into a manufacturing education curriculum. There is no better way to consolidate the basic engineering knowledge in this domain than building or upgrading a CNC machine tool. The original controller of the particular machine, which was used as a test bed, was outdated in several respects: restricted command range, semimanual operation of the main spindle and the tool magazine, and lack of graphical simulation of the tool path. A software-based open controller was substituted for the original controller, running on a PC with a stable operating system and enabling improvements in several aspects of the machine tool's functionality as well as flexible future extensions, as needed. Upgrading encompasses custom-designed PCBs as interfaces between the control signals and the machine's power circuits, addition of limit and homing switches, complete tool magazine upgrading with a position sensor, and a microcontroller to achieve fully automated tool change and automatic movement of the tailstock quill. The updated functionality was tested by successfully manufacturing several test workpieces, one of which is briefly presented.