How would you inspect a hole that has a true position tolerance and a diameter tolerance?

How would you inspect a hole that has a true position tolerance and a diameter tolerance?

• A. Check surface finish
• B. Inspect length and depth
• C. Verify the hole axis location with true position tolerance and verify hole size with diameter tolerance
• D. Check perpendicularity and runout

Answer: (C)

When a hole has both a true position tolerance and a diameter tolerance, you must control two things: where the hole’s axis sits, and how big the hole is. The true position tolerance specifies how far the actual hole axis can deviate from its intended location relative to the defined datum references. The diameter tolerance specifies the allowable variation in the hole’s size. To inspect, verify that the hole axis location lies within the true position tolerance zone when referenced to the datums, and separately verify that the hole diameter falls within the specified diameter tolerance. In practice, a CMM is a common tool for checking both the axis position and the diameter, though bore gauges or plug gauges can be used for the diameter as needed. Other checks like surface finish, simple length/depth, or orientation features (perpendicularity or runout) aren’t addressing the two tolerances given here, so they’re not the focus of this inspection.

When a hole has both a true position tolerance and a diameter tolerance, you must control two things: where the hole’s axis sits, and how big the hole is. The true position tolerance specifies how far the actual hole axis can deviate from its intended location relative to the defined datum references. The diameter tolerance specifies the allowable variation in the hole’s size.

To inspect, verify that the hole axis location lies within the true position tolerance zone when referenced to the datums, and separately verify that the hole diameter falls within the specified diameter tolerance. In practice, a CMM is a common tool for checking both the axis position and the diameter, though bore gauges or plug gauges can be used for the diameter as needed.

Other checks like surface finish, simple length/depth, or orientation features (perpendicularity or runout) aren’t addressing the two tolerances given here, so they’re not the focus of this inspection.