Question 1

Forms of dimension expression Dimensions are communicated as distances, angles, and notes in both metric and inch systems; this practice is not limited to metric-only drawings.

Accepted Answer

Introduction / Context: Drawings worldwide use a consistent set of methods to convey requirements: linear and angular dimensions, plus notes for specifications that do not fit neatly into numeric callouts. These methods apply regardless of unit system—metric (SI) or inch—so teams can communicate clearly in any context. Given Data / Assumptions: A project may use SI, inch, or dual units. Angles, lengths, and textual notes appear together to define requirements. Standards specify unit formatting and notation for each system. Concept / Approach: A complete drawing typically mixes: distances (for lengths, diameters, radii), angles (for tapers, chamfers, and rotations), and notes (for finishes, coatings, processes, and defaults). The presentation style differs slightly by standard and units (for example, decimal separators or leading zeros), but the fundamental trio—distances, angles, notes—is universal. Step-by-Step Solution: Declare the unit system in the title block.Apply linear and angular dimensions with consistent formatting (e.g., mm without unit repetition per ISO, inches with trailing zeros per company policy).Use notes for specifications like surface finish, heat treatment, or general radii/chamfers.Ensure no conflict exists between notes and numeric dimensions. Verification / Alternative check: Review with a unit-conversion check: if a dual-unit drawing is required, verify conversion rounding does not create ambiguous tolerances. Why Other Options Are Wrong: Stating “Correct” or limiting to SI-only, dual-dimensioned, or welded assemblies misunderstands the universal nature of these expression forms. Common Pitfalls: Mixing unit formats, omitting unit declaration, or placing conflicting instructions between notes and callouts. Final Answer: Incorrect

Question 2

Scale indication on drawings Engineering drawings are usually prepared to a defined scale, and that scale is identified in the title block or a dedicated note on the sheet.

Accepted Answer

Introduction / Context: Drawings are representations, not necessarily full-size depictions. To manage sheet size and readability, views are scaled up or down. The declared scale informs readers how the drawing’s geometry relates to real size and allows accurate use of printed dimensions and visual checks. Given Data / Assumptions: Views may be enlarged (e.g., 2:1) or reduced (e.g., 1:2). The title block provides the default sheet scale; individual views can override it if needed. Dimensions remain controlling, not the physical measurement of the printed view. Concept / Approach: The title block typically lists the default scale (for example, SCALE: 1:1). Detail views may carry their own scale note when they differ from the default (for example, SCALE: 4:1). This avoids confusion when checking proportions and ensures that any manual measuring or overlaying is done with the correct expectation. Step-by-Step Solution: Determine the appropriate default scale for overall layout.Override scale on specific views that require enlargement or reduction.Label all deviations from the default clearly near the view.Confirm that plotted output maintains intended scale (no unintended printer scaling). Verification / Alternative check: Use a printed scale bar for a quick visual confirmation that the plot is at the intended scale. Why Other Options Are Wrong: Saying the scale is never shown or only needed on assemblies is incorrect. A mandatory 1:1 requirement is impractical and unnecessary; dimensions, not rulers on the paper, control. Common Pitfalls: Forgetting to update the title block after view scale changes, or letting printer settings “fit to page” and distort the intended scale. Final Answer: Correct

Question 3

Metric whole-number formatting According to common metric drawing conventions, a metric dimension that is a whole number is written without a decimal point or trailing zero (for example, 12 rather than 12.0).

Accepted Answer

Introduction / Context: Consistent numeric formatting improves readability and prevents misinterpretation. In metric drawings, whole-number dimensions are typically shown without decimal points or trailing zeros. This convention keeps the drawing clean and reduces confusion about implied precision while still allowing tolerances to control actual acceptance limits. Given Data / Assumptions: The drawing uses SI (metric) units. Default tolerance policy is stated in the title block or per-feature. Readers understand that the number of decimal places does not alone define tolerance unless specified by a drawing convention. Concept / Approach: Many organizations follow the practice: whole numbers without decimals (e.g., 12), and decimals used only when needed (e.g., 12.5). Precision and acceptance are governed by explicit tolerances (limits, ± values, or tables), not by writing 12.0 versus 12.00. This helps avoid implying false precision and keeps attention on the tolerance specification. Step-by-Step Solution: Declare units (mm) and default tolerances in the title block.Express whole-number dimensions without decimal points (e.g., 16).Use decimals only where fractional values exist (e.g., 16.2) or where company policy requires.Apply tolerances explicitly to control variation (e.g., 16 ± 0.1 or limits). Verification / Alternative check: Audit the drawing for consistency and ensure the CAD dimension style matches the metric formatting rules adopted by your organization. Why Other Options Are Wrong: Restricting the rule to specific disciplines or part types is incorrect. Tolerances, not decimal places, control precision; therefore “Only true when toleranced” is misleading. Common Pitfalls: Mixing inch-style formatting conventions with metric, adding unnecessary zeros that suggest tighter than intended precision, or leaving the title-block tolerance ambiguous. Final Answer: Correct

Question 4

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.

Accepted Answer

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

Question 5

Drafting convention check: Should a heavy straight underline be drawn beneath all dimension values that are “to scale,” or is that not a standard practice in modern technical drawings?

Accepted Answer

Introduction / Context: Dimensioning communicates the true intended size of features regardless of drawing scale. Conventions like underlining, brackets, or special symbols exist in some legacy contexts, but current standards emphasize clarity without unnecessary adornments. This question tests whether underlining all “to scale” dimensions is recommended practice. Given Data / Assumptions: Modern drawings show true sizes with dimension text, independent of graphic scale. “Not to scale” conditions are typically indicated by general notes or local annotations, not by underlining all other values. Heavy underlines can add clutter and are not part of mainstream standards for normal dimensions. Concept / Approach: Dimensions are authoritative; the model or drawing graphics are secondary. Whether or not a drawn view is perfectly scaled, the numerical dimension stands as the requirement. As a result, standards do not call for a heavy underline under every dimension that happens to be graphically to scale. Instead, atypical conditions (e.g., NTS) are explicitly noted. Step-by-Step Solution: Recognize that dimension text defines requirement, independent of graphic scale.Identify that highlighting “to scale” values is unnecessary and nonstandard.Note that special cases (reference or NTS) are handled with notes/symbols, not bulk underlining.Conclude the proposed heavy underline practice is not standard—statement is incorrect. Verification / Alternative check: Review drafting guides: dimensions are presented plainly; exceptions are called out specifically rather than underlining normal conditions. Why Other Options Are Wrong: “Correct” conflicts with standard practice. Use in architecture, reduced scales, or inspection-critical dimensions does not establish a universal rule. Common Pitfalls: Over-annotating drawings; mixing up legacy shop-floor markings with formal drafting standards. Final Answer: Incorrect

Dimensioning Questions