also developing new manually and automatically controlled lathes. The technological developments in America and Switzerland flowed rapidly into other industrialized countries (via routes such as machine tool exports; trade journal articles and advertisements; trade shows, from world's fairs to regional events; and the turnover and emigration of engineers, setup hands, and operators). There, local innovators also developed further tooling for the machines and built clone machine models. The development of numerical control was the next major leap in the history of automatic lathes—and it is also what changed the paradigm of what the "manual versus automatic" distinction meant. Beginning in the 1950s, NC lathes began to replace manual lathes and cam-op screw machines, although the displacement of the older technology by CNC has been a long, gradual arc that even today is not a total eclipse. By the 1980s, true CNC screw machines (as opposed to simpler CNC lathes), Swiss-style and non-Swiss, had begun to make serious inroads into the realm of cam-op screw machines. Similarly, CNC chuckers were developed, eventually evolving even into CNC rotary transfer machines. These machine tools are little known outside the automotive manufacturing sector. References Bibliography External links YouTube video showing a 1965 cam-op screw machine in action. YouTube video showing another cam-op screw machine. Automatic lathes