SkillsUSA CNC Milling Practice Exam 2025 - Free CNC Milling Practice Questions and Study Guide

The command used to clear offsets in CNC programming is G40. This command specifically cancels any tool radius compensation that may currently be in effect, which is essentially related to managing offsets during machining processes.

Tool radius compensation allows the programmer to adjust the tool path based on the diameter of the cutting tool, ensuring precision in machining operations. By using G40, the machine can revert to its nominal path without any modified offsets, which is particularly important in scenarios where precision is crucial.

In this context, it’s key to note that other commands, while relevant to various operations, do not specifically serve the purpose of clearing offsets. For instance, G28 is used for returning the machine to its home position, G90 sets the machine to absolute programming mode, and G92 is often used for setting a specific position within the program but does not clear offsets.