Question 158General Subjects - QMED

The correct answer is A) lead screw and headstock spindle. When a lathe is used for thread cutting, the number of threads per inch produced is determined by the speed relationship between the lead screw and the headstock spindle. The lead screw is responsible for advancing the carriage and cutting the threads, while the headstock spindle provides the rotational motion to the workpiece. By adjusting the relative speeds of these two components, the operator can control the number of threads per inch being cut. The other options are incorrect because they do not directly influence the thread pitch. The relationship between the drive motor and spindle (option B) affects the overall spindle speed, but not the specific thread pitch. The relationship between the spindle and feed rod (option C) determines the feed rate, but not the thread pitch. The relationship between the lead screw and feed rod (option D) affects the carriage movement, but not the thread pitch.