Millwright Level 1 Practice Exam 2026 – All-in-One Guide to Master Your Certification!

The center head and rule combination set is specifically designed for locating the center of circular objects, such as the end of a shaft. The center head features pointed ends that can be positioned on the outer edges of the shaft, allowing for the easy marking of the diameter's midpoint. When the ruler is used in conjunction with the center head, it provides a reference line to ensure that the center is accurately determined. This method is essential in tasks such as drilling, where finding the exact center is crucial for maintaining balance and accuracy in the operation.

Other options do not serve this specific purpose as effectively. The straight edge and square are used for checking squareness and guiding cuts, while the protractor and height gauge are primarily for measuring angles and heights respectively. Calipers and micrometers, although useful for measuring dimensions, are not tailored for centering applications on circular objects. Therefore, using the center head with a rule is the optimal choice for finding the center on the end of a shaft.