Which tool is used to find the center of a shaft or other cylindrical work?

Which tool is used to find the center of a shaft or other cylindrical work?

• A. Dial indicator
• B. Combination set
• C. Micrometer caliper
• D. Machinist scale

Answer: (B)

Finding the center of a cylindrical work relies on laying out geometry that reveals the axis of the circle. A combination set lets you do this by providing a ruler, a compass/divider, and adjustable square features in one tool. You can use it to draw chords across the shaft, then construct perpendicular bisectors with the compass and straightedge functions. The point where those bisectors intersect marks the center of the circle, giving you the centerline of the shaft for subsequent operations like center drilling or turning between centers. The other tools aren’t as directly suited for this task. A dial indicator measures runout and alignment relative to a reference surface, but doesn’t by itself locate the center of a circular cross-section. A micrometer caliper gives you precise diameters or thicknesses, not the center position of a cylindrical work. A machinist scale is a straight measuring tool and doesn’t provide the geometric construction needed to pinpoint the center.

Finding the center of a cylindrical work relies on laying out geometry that reveals the axis of the circle. A combination set lets you do this by providing a ruler, a compass/divider, and adjustable square features in one tool. You can use it to draw chords across the shaft, then construct perpendicular bisectors with the compass and straightedge functions. The point where those bisectors intersect marks the center of the circle, giving you the centerline of the shaft for subsequent operations like center drilling or turning between centers.

The other tools aren’t as directly suited for this task. A dial indicator measures runout and alignment relative to a reference surface, but doesn’t by itself locate the center of a circular cross-section. A micrometer caliper gives you precise diameters or thicknesses, not the center position of a cylindrical work. A machinist scale is a straight measuring tool and doesn’t provide the geometric construction needed to pinpoint the center.