Dimensioning fundamentals in technical drawing: Is the “nominal size” of a feature the exact measured size after applying tolerances, or is it the target/identifying size before tolerances are considered? Evaluate the statement.

Introduction / Context:
In engineering drawings and manufacturing, clear terminology around size is essential. “Nominal size,” “basic size,” “limits,” and “tolerances” each carry precise meanings that determine how parts are produced and inspected. This question tests whether nominal size represents the exact as-produced dimension after tolerances, or the nameplate/target value before variation is applied.

Given Data / Assumptions:

• Nominal size is used to identify or designate a feature (for example, a “10 mm shaft” or a “1/2 in bolt”).
• Actual size is the measured size of the finished feature.
• Tolerances establish the permissible variation around a target size via upper and lower limits.
• No special standard overrides are assumed.

Concept / Approach:
Nominal size functions as the convenient label or target from which limits are derived. It does not imply the exact achieved measurement. The produced dimension must fall within the specified tolerance band around the intended value. Therefore, equating nominal size to the post-tolerance exact measurement confuses identification with measurement.

Step-by-Step Solution:
Identify definition: nominal size = identifying/target value, often the basis of a size series.Contrast with actual size: the measurement taken on the produced part.Relate to tolerances: limits = nominal (or basic) ± tolerance; actual must lie within.Conclude: nominal is not the exact result after tolerance—statement is incorrect.

Verification / Alternative check:
Check any standard parts catalog: “Nominal 10 mm” shafts will have allowable plus/minus limits; measured values vary but remain within limits, proving nominal is not the exact, post-tolerance size.

Why Other Options Are Wrong:
“Correct” reverses the definitions. “Only for ISO fits,” “Only for sheet-metal,” and “Reference dimensions only” add conditions that do not change nominal-size meaning.

Common Pitfalls:
Assuming nominal equals actual; ignoring that inspection certificates report measured values, not nominal labels.

Final Answer:
Incorrect