CDT CDT Structural & Mechanical Drafting 2 — Questions and Answers
Question 1: Which projection method is standard in the United States for engineering drawings?
- First-angle projection
- Third-angle projection (Correct answer)
- Second-angle projection
- Oblique projection
Correct answer: Third-angle projection
Third-angle projection is the standard method used in the US, where the view is placed on the same side as the observer relative to the part.
Question 2: What does a centerline (alternating long and short dashes) represent on a mechanical drawing?
- A phantom line showing an alternate position
- The axis of symmetry or center of a circular feature (Correct answer)
- A cutting plane line
- A break line for shortened views
Correct answer: The axis of symmetry or center of a circular feature
Centerlines mark the axis of symmetry of a part, the center of holes or cylinders, or the pitch circle of bolt patterns.
Question 3: A bill of materials (BOM) on a mechanical assembly drawing typically includes which information?
- Only the part names and quantities
- Item number, part number, description, quantity, and material (Correct answer)
- Only the cost and lead time of each part
- The manufacturing sequence and tooling requirements
Correct answer: Item number, part number, description, quantity, and material
A BOM is a structured list that includes each item's number, part number or drawing number, description, quantity required, and often material specification.
Question 4: In structural drafting, what does a break line indicate?
- A crack or defect in the structure
- That a long part has been shortened and the middle portion removed from the view (Correct answer)
- A weld joint between two members
- A dimension that falls outside the drawing border
Correct answer: That a long part has been shortened and the middle portion removed from the view
Break lines are used when a long uniform object is too large to draw at full scale; the middle is removed and the ends are brought together with a break symbol.
Question 5: What is a revision block (revision history) on an engineering drawing used for?
- Recording who printed the drawing
- Tracking changes made to the drawing after initial release (Correct answer)
- Listing approved vendors for the part
- Documenting the inspection results
Correct answer: Tracking changes made to the drawing after initial release
The revision block records each change made to the drawing after release, including the revision letter/number, description of change, date, and approver.
Question 6: Which line type on a structural or mechanical drawing indicates an alternate position or a repeated feature?
- Hidden line (dashed)
- Phantom line (long-short-short dashes) (Correct answer)
- Section line (diagonal hatching)
- Cutting plane line
Correct answer: Phantom line (long-short-short dashes)
Phantom lines are used to show alternate positions of moving parts, repeated details, or the outline of adjacent parts for reference.
CDT CDT Structural & Mechanical Drafting 2
Which projection method is standard in the United States for engineering drawings?