How would you specify a position tolerance for a hole pattern to ensure all centers remain within a common zone?

How would you specify a position tolerance for a hole pattern to ensure all centers remain within a common zone?

• A. Apply a basic dimension to locate the centers.
• B. Apply a pattern position tolerance with a circular tolerance zone defined for the pattern's centers.
• C. Apply a pattern position tolerance with a diameter tolerance relative to the DRF, referencing the datums as needed.
• D. Apply a pattern runout tolerance to the entire pattern.

Answer: (C)

To keep all centers of a hole pattern inside one shared tolerance envelope, you control their true positions with a pattern position tolerance that uses a cylindrical tolerance zone (shown with a diameter) anchored to a datum reference frame. By tying that tolerance to the DRF and the required datum features, the entire pattern must stay within the same envelope relative to the datums. This ensures every hole center remains within a common zone as the part is measured against the reference frame. Using a basic dimension alone won’t define any positional tolerance, so it won’t guarantee a controlled envelope. A pattern position tolerance that isn’t explicitly referenced to the datum reference frame wouldn’t establish the common zone relative to the datums. A pattern runout applies to the pattern’s relationship during rotation around a datum axis and doesn’t establish a fixed common zone for the centers in the plane.

To keep all centers of a hole pattern inside one shared tolerance envelope, you control their true positions with a pattern position tolerance that uses a cylindrical tolerance zone (shown with a diameter) anchored to a datum reference frame. By tying that tolerance to the DRF and the required datum features, the entire pattern must stay within the same envelope relative to the datums. This ensures every hole center remains within a common zone as the part is measured against the reference frame.

Using a basic dimension alone won’t define any positional tolerance, so it won’t guarantee a controlled envelope. A pattern position tolerance that isn’t explicitly referenced to the datum reference frame wouldn’t establish the common zone relative to the datums. A pattern runout applies to the pattern’s relationship during rotation around a datum axis and doesn’t establish a fixed common zone for the centers in the plane.