These machines were used historically in machining and manufacturing before the widespread adoption of CNC (Computer Numerical Control) technology. Tracer lathes and mills are manually operated machines that use mechanical or hydraulic systems to follow a template or master model. The tracer mechanism duplicates the shape and movements of the template onto the workpiece, allowing for the replication of complex contours and profiles. While they are not as precise or versatile as CNC machines, tracer lathes and mills were valuable tools for producing intricate parts and components in the past. Their use has become less common with the advent of CNC technology, which offers greater automation, precision, and flexibility in machining operations.