What does true position refer to in GD&T?

What does true position refer to in GD&T?

• A. The measured position.
• B. The maximum material condition.
• C. The theoretical target.
• D. The projection height.

Answer: (C)

True position is the theoretical target location of a feature relative to the datum reference frame. It's the exact position the feature would have if the part were perfect, defined by the datums and the design intent. When a positional tolerance is specified, you’re allowing an acceptable deviation from this ideal target by creating a tolerance zone around the true position; the actual feature must lie inside that zone to be acceptable. This isn’t the measured position you read off after manufacturing, and it isn’t about size (that would be maximum material condition) or about a projection height. For a hole, the true position refers to the exact axis location and orientation the hole should have in the ideal part, and the tolerance governs how far the actual hole’s axis may stray from that axis.

True position is the theoretical target location of a feature relative to the datum reference frame. It's the exact position the feature would have if the part were perfect, defined by the datums and the design intent. When a positional tolerance is specified, you’re allowing an acceptable deviation from this ideal target by creating a tolerance zone around the true position; the actual feature must lie inside that zone to be acceptable.

This isn’t the measured position you read off after manufacturing, and it isn’t about size (that would be maximum material condition) or about a projection height. For a hole, the true position refers to the exact axis location and orientation the hole should have in the ideal part, and the tolerance governs how far the actual hole’s axis may stray from that axis.