SkillsUSA CNC Milling Practice Exam – Complete Prep with Practice Tests and Study Guide

In the context of CNC milling, the command G20 is used to specify inch positioning for the machine. When this command is activated, it informs the CNC controller that measurements will be provided in inches rather than the metric system. This is crucial because it sets the standard unit of measurement for all subsequent commands and operations in the machining process.

Choosing inch positioning allows for a more familiar frame of reference for operators who commonly work in imperial units, particularly in regions where inch measurements are standard. Understanding such commands is essential for correctly interpreting and executing CNC programs, as incorrect unit settings can lead to significant errors in machining specifications and component dimensions.

While the other options relate to different functions in CNC programming, they do not pertain to the specific purpose of G20. For instance, counterclockwise rotation, tool path alteration, and cutter compensation all involve different G-code commands that are unrelated to setting measurement units.