NCCER Millwright Practice Exam

What is the function of the head of a telescoping gauge?

1. To measure depth accurately

2. To measure the thickness of materials

3. To accurately measure inner diameters

4. To measure external dimensions

The correct answer is: To accurately measure inner diameters

The function of the head of a telescoping gauge is primarily to accurately measure inner diameters. This tool is specifically designed to reach into cylindrical spaces or holes, capturing measurements with precision. The design of the gauge incorporates adjustable arms that expand outward, allowing it to conform to the contours of the inner surface being measured. When the gauge is used, the head expands inside the inner diameter until it makes contact with the walls of the hole. This ensures that the measurement taken reflects the true inner diameter of the object. After the gauge is withdrawn, it can be transferred to a micrometer or caliper to provide a precise measurement of the diameter. Other options describe functions that do not align with the specific design and purpose of a telescoping gauge. For example, measuring depth accurately is typically the role of a depth gauge, while measuring thickness or external dimensions often involves the use of calipers or other types of measuring tools that serve those specific functions. Thus, understanding the specialized use of the telescoping gauge for measuring inner diameters clarifies why it is the correct choice in this context.