How would you interpret a callout with 'Ø0.050' and a position tolerance '0.010 A B'?

• A. The diameter tolerance of 0.010 and a position at Ø0.050.
• B. The hole axis must lie within a cylindrical zone of diameter 0.010 relative to datums, while the hole's size must be within 0.050 diameter.
• C. The hole axis must lie within 0.050 relative to datums, while the diameter tolerance is 0.010.
• D. The hole axis must be within a 0.050 cylindrical zone; the datums are not used.

Answer: (B)

The key idea here is how GD&T separates where a feature goes from how big the feature is. A position tolerance (0.010 A B) defines a cylindrical tolerance zone for the axis of the hole. That means the hole’s axis must lie within a cylinder whose diameter is 0.010, and this cylinder is located and oriented relative to the datums A and B.

The Ø0.050 part specifies the size constraint of the hole itself—the hole diameter must be within that Ø0.050 size tolerance.

So, both requirements must be met at once: the hole’s axis must be located within a 0.010-diameter cylindrical zone relative to datums A and B, and the hole’s diameter must stay within Ø0.050. The datums are used to define the reference frame for the true position.

This interpretation distinguishes the two values: the smaller 0.010 governs the true position (axis location), while the larger Ø0.050 governs the hole’s size. The other readings would mix up which value controls position versus size or ignore the datum references.