Dimensioning practice: Is it acceptable drafting practice to place dimensions to hidden features (features shown only with hidden lines) instead of showing those features in a visible or sectioned view?

Introduction / Context:
Clear dimensioning ensures that machinists and fabricators can interpret drawings without confusion. A frequent rule taught in standards-based drafting is to avoid dimensioning to hidden lines, because hidden geometry is inherently harder to read and can lead to errors.

Given Data / Assumptions:

• We follow common drafting standards practices (e.g., ASME Y14 series).
• Hidden lines indicate features not visible in the current view.
• Views and sections can be added to reveal features clearly.

Concept / Approach:
Dimensioning should reference visible edges or centerlines in views where the geometry is shown clearly. If a feature is hidden in all chosen principal views, create an auxiliary or section view so the feature appears visibly. This reduces misinterpretation and improves manufacturability. Dimensions attached to hidden lines are harder to track and may be missed during inspection.

Step-by-Step Solution:

Verification / Alternative check:
Compare two drawings of the same part: one dimensioned to hidden lines and another dimensioned in a section view. The sectioned version will be easier to read and less prone to mistakes, confirming best practice.

Why Other Options Are Wrong:

• “Always dimension to hidden features” contradicts standards guidance.
• “Preferred for all holes and pockets” is incorrect; sections or visible views are preferred.
• “Assembly drawings by default” is not a blanket exception; clarity still rules.
• Limited exceptions exist, but the general rule is to avoid hidden-line dimensioning whenever a clearer alternative exists.

Common Pitfalls:
Saving sheet space at the cost of clarity; forgetting to add a section view; placing dimensions on cluttered hidden-line areas that lead to misreading on the shop floor.

Final Answer:
Incorrect: avoid dimensioning to hidden lines; use a visible or section view