14.3 Dimensioning, BOM, Projection Standards & GD&T

14.3 Dimensioning, BOM, Projection Standards & GD&T

Quick Answer: Use Smart Dimension (and Model Items) to place size/location dimensions on views; use balloons + Bill of Materials for assembly callouts; read title block fields and projection symbols for standards; recognize basic GD&T symbols (flatness, perpendicularity, position, datum feature, MMC) at associate level—identification, not full tolerance stack analysis.

Views without dimensions and notes are incomplete manufacturing documents. CSWA does not require you to fully detail a production drawing under the clock the way a drafting job would, but the Drafting Competencies items expect you to know what tools and symbols mean. This section finishes that vocabulary.

Dimensioning tools in SOLIDWORKS drawings

Smart Dimension

On a drawing sheet, Smart Dimension (same family as sketch Smart Dimension) attaches dimensions to view geometry: edges, vertices, hole diameters, angles between lines, etc. You click entities in a view, place the dimension text, and the dimension stays associative to the model—change the part, and driving model dimensions update; drawing dimensions that reference model geometry update after rebuild.

Exam angle: Questions may ask which tool adds dimensions on a drawing. Smart Dimension is the primary answer. Marking menu / annotation toolbar placement still counts as Smart Dimension workflow.

Model Items

Insert → Model Items brings dimensions, hole callouts, annotations, and reference geometry marks from the 3D model into selected drawing views. This is efficient when the part was fully dimensioned in sketches/features: you import rather than re-dimension everything by hand.

Trap: Model Items can flood a view with every sketch dimension. Production practice cleans and rearranges; theory questions still test that Model Items imports model-based annotations/dimensions into the drawing.

Annotation types (conceptual list)

Beyond pure dimensions, drawings use:

• Notes — text instructions, finish notes, general tolerances
• Hole callouts — hole wizard-style threaded/simple hole specs
• Center marks / centerlines — for holes and symmetry
• Datum feature symbols — GD&T reference frames (below)
• Geometric tolerance frames — feature control frames
• Surface finish / weld symbols — may appear in figures; rare deep testing on CSWA
• Balloons — item numbers for assemblies

You do not need every annotation PropertyManager option memorized—recognize what family an annotation belongs to when a figure is shown.

Balloons and Bill of Materials (BOM)

Balloons

Balloons (auto-balloon or manual) place circled item numbers on assembly drawing views. Each balloon points to a component instance and matches a row in the Bill of Materials.

If a question shows circled numbers on an assembly isometric with leaders to parts, those are balloons, not section labels (section labels pair with cutting lines) or detail labels (detail circles).

Bill of Materials table

Insert → Tables → Bill of Materials creates a BOM table on an assembly drawing. Typical columns:

BOM is a table, not a view. It lists parts in the assembly (top-level or parts-only/ indented options in the PropertyManager). CSWA-level recognition: BOM = parts list table linked to balloons.

Title block fields (conceptual)

The title block (sheet format) holds drawing metadata. Concept-level fields:

SOLIDWORKS links many title block attributes to custom properties of the model or sheet. For CSWA, know that projection method and scale often live in the title block/format, and that third-angle vs first-angle may be indicated by symbol there (ties to 14.1).

Projection standards — drawing communication recap

CSWA MC pattern: “This title block shows which projection?” or “Which is default for US ANSI templates?” → Third-angle. Do not answer first-angle unless the figure is clearly ISO/first-angle layout or the stem says ISO.

GD&T at associate recognition level

Geometric Dimensioning and Tolerancing (GD&T) uses standardized symbols to control form, orientation, location, and runout beyond simple ± size tolerances. CSWA is not a GDTP certification—you need symbol recognition and basic meaning, not advanced bonus tolerance math for every case.

Feature control frame (concept)

A rectangular feature control frame holds:

1. Geometric characteristic symbol (e.g., flatness, position)
2. Tolerance value (and material condition modifiers if any)
3. Datum references (primary, secondary, tertiary as required)

Example structure (conceptual): [ ⟂ | 0.1 | A ] means perpendicularity within 0.1 relative to datum A (actual drawing frames use the proper symbol cells).

High-yield symbols for CSWA-style recognition

Datums

A datum is a theoretically exact reference (plane, axis, point) established from a datum feature on the part. The datum feature symbol on the drawing points to the real feature (a face, a hole, etc.). Position and perpendicularity frames commonly reference datums; flatness as pure form often does not.

MMC intro (associate depth only)

Maximum Material Condition (MMC) is the condition where the feature contains the maximum amount of material within size limits:

• For a pin/external feature: MMC ≈ largest size
• For a hole/internal feature: MMC ≈ smallest size

The Ⓜ modifier in a feature control frame means the geometric tolerance is stated at MMC; as the actual feature size leaves MMC (hole gets larger, pin gets smaller), bonus tolerance may become available. CSWA may only ask you to identify MMC or know it relates to material condition—not to compute a full stack.

LMC (Least Material Condition, Ⓛ) is the opposite idea; know the name exists. RFS (Regardless of Feature Size) is implied when no material condition modifier is shown on many controls—recognize that absence of Ⓜ/Ⓛ often means RFS at associate level if asked.

Size dimension vs geometric control

Trap: Treating a position frame as “just another diameter dimension.” Diameter still needs a size dimension; position controls where the feature is relative to datums.

Putting annotations together on an assembly drawing

Typical associate-level assembly sheet content:

1. Isometric or multiview of the assembly
2. Balloons on components
3. BOM table with matching item numbers
4. Maybe a few overall dimensions or a note “SEE PART DRAWINGS FOR DETAILS”
5. Title block with scale, projection symbol, revision

Part drawings emphasize orthographics + sections/details + dimensions + GD&T more heavily than balloons/BOM.

Common CSWA drafting traps (full category)

Exam-day drafting sprint (all of Chapter 14)

Study drills that transfer

1. Open any ANSI template drawing of a simple block: confirm third-angle symbol and Top-above-Front layout.
2. Add Standard 3 View, project an isometric, add a section, a detail at 2:1, and an auxiliary on a chamfered face—label each aloud.
3. Insert Model Items, then delete clutter and place two Smart Dimensions manually.
4. On an assembly drawing, Auto Balloon + BOM; match item numbers.
5. Flashcard the five GD&T recognition items: flatness, perpendicularity, position, datum feature, MMC.

Drafting is only 15 points, but it is pure knowledge—no rebuild failures, no unit typos. Combined with strong parts and assemblies, these recognition skills protect the cut score. You have now closed the official CSWA skill map’s drafting category: views, specialized projections, and the annotation/BOM/GD&T language the associate exam expects you to read.