CDT Materials & Equipment Knowledge 2 — Questions and Answers
Question 1: Which lead grade is most appropriate for lettering on a finished engineering drawing?
- 4H
- 2H (Correct answer)
- HB
- 6B
Correct answer: 2H
2H lead provides clean, dark, consistent lines suitable for lettering without smearing or indenting the paper excessively.
Question 2: What is the primary advantage of using vellum over bond paper for hand drafting?
- It is less expensive to produce
- It allows superior erasure and is semi-transparent for reproduction (Correct answer)
- It is more resistant to moisture damage
- It accepts ink more readily without bleeding
Correct answer: It allows superior erasure and is semi-transparent for reproduction
Vellum's semi-transparency allows it to be used as an overlay or original for reproduction, and its surface erases more cleanly than bond paper.
Question 3: A drafting machine combines the functions of which two traditional drafting tools?
- T-square and protractor (Correct answer)
- Compass and dividers
- French curve and ruler
- Triangle and scale
Correct answer: T-square and protractor
A drafting machine replaces both the T-square (for horizontal reference) and the protractor (for angular measurement) in a single adjustable head.
Question 4: Which type of drafting scale is used primarily for maps and site plans where large areas must be reduced?
- Architect's scale
- Engineer's scale (Correct answer)
- Metric scale
- Decimal scale
Correct answer: Engineer's scale
The engineer's scale uses decimal divisions (1"=10', 20', 30', etc.) making it ideal for civil/site drawings covering large geographic areas.
Question 5: What is the recommended method for cleaning a drawing surface before starting a new drawing?
- Wipe with a damp cloth to remove oils
- Dust with a dry drafting brush to remove loose particles (Correct answer)
- Apply drafting powder and spread with a cloth
- Use compressed air to blow away debris
Correct answer: Dust with a dry drafting brush to remove loose particles
A dry drafting brush removes eraser debris and dust without introducing moisture or oils that could damage the drawing surface or affect pencil adhesion.
Question 6: Mylar (polyester film) is preferred over vellum for original drawings that will be revised repeatedly because it:
- Is significantly cheaper per sheet
- Allows pencil lines to be darker
- Withstands repeated erasure without surface degradation (Correct answer)
- Accepts standard graphite without surface preparation
Correct answer: Withstands repeated erasure without surface degradation
Polyester film is dimensionally stable and its surface can withstand many more erasures than vellum without pilling, ghosting, or tearing.
Question 7: When using a ruling pen with India ink, the gap between the nibs should be adjusted to control:
- Ink drying time
- Line weight (width) (Correct answer)
- Ink opacity
- Drawing angle
Correct answer: Line weight (width)
The nib gap on a ruling pen directly determines how wide the ink flow is, thus setting the line weight of the drawn line.
CDT Materials & Equipment Knowledge 2
Which lead grade is most appropriate for lettering on a finished engineering drawing?