Millwright Level 1 Practice Exam 2026 - Free Millwright Practice Questions and Study Guide

The function of the thread chasing dial is to time the engagement of the split nut when cutting a thread. This is crucial for accurately cutting threads on a lathe. When a thread is being cut, it is essential for the tool to return to its starting position to align with the previous cut. The thread chasing dial, often marked with numbered divisions, helps the operator to determine the correct moment to engage the split nut again for a subsequent cut. This timing ensures that the new cut aligns perfectly with the existing thread, creating a properly formed thread without gaps or overlaps.

The other options relate to different functions that do not pertain directly to the specific role of the thread chasing dial. Adjusting the feed rate, measuring thread depth, and controlling spindle speed are all important operations in machining, but they are managed by different mechanisms and settings on the lathe rather than through the thread chasing dial. Thus, the correct option highlights the precise task of ensuring the split nut engages at the right time during the thread cutting process.