Tracer-controlled position regulator for propeller milling machine

IN a companion paper by Rutemiller and Morton¹ the electrical control of an automatic machine for milling ship propellers up to 24 feet in diameter is described. The outstanding features of this machine, which is illustrated in Figure 1, are the speed and accuracy with which it can generate the desired blade contours in conformity with scale models. These features permit enormous savings in time over previous methods of propeller machining. This superior performance is made possible largely by the use of two tracer-controlled regulators to control the positioning of milling cutters which machine both faces of the blades simultaneously. It is the purpose of this paper to describe the design features and performance characteristics of the regulators and to indicate by means of a typical stability calculation in an appendix some of the theoretical considerations involved in their development. Although the regulating system described was designed specifically for the propeller milling machine, it may be used, with some modifications, in other machine-tool applications, as well as in other fields.