Which gauge is used to inspect external cylindrical features such as a shaft?

Which gauge is used to inspect external cylindrical features such as a shaft?

• A. Ring gauge
• B. Plug gauge
• C. Caliper
• D. Dial gauge

Answer: (A)

For checking external cylindrical dimensions, a specialized external gauge called a ring gauge is used. Its internal bore is made to an exact diameter, so the shaft’s outside diameter must fit through the ring within tolerance. This provides a fast, repeatable go/no-go check: if the shaft passes, its external size is within the specified range; if it doesn’t, it’s out of tolerance. A plug gauge checks holes (internal features), not the outside of a shaft. A caliper can measure outside diameters, but it relies on the operator’s technique and isn’t a fixed go/no-go standard for quick production checks. A dial gauge measures deviations such as runout or alignment, not the nominal external diameter of a cylindrical part.

For checking external cylindrical dimensions, a specialized external gauge called a ring gauge is used. Its internal bore is made to an exact diameter, so the shaft’s outside diameter must fit through the ring within tolerance. This provides a fast, repeatable go/no-go check: if the shaft passes, its external size is within the specified range; if it doesn’t, it’s out of tolerance.

A plug gauge checks holes (internal features), not the outside of a shaft. A caliper can measure outside diameters, but it relies on the operator’s technique and isn’t a fixed go/no-go standard for quick production checks. A dial gauge measures deviations such as runout or alignment, not the nominal external diameter of a cylindrical part.