CDT Materials & Equipment Knowledge 3 — Questions and Answers
Question 1: What does the term 'tooth' refer to when describing a drafting surface?
- The hardness rating of the paper
- The slight texture that helps pencil graphite adhere to the surface (Correct answer)
- The weight of the paper in grams per square meter
- The translucency percentage of vellum
Correct answer: The slight texture that helps pencil graphite adhere to the surface
Tooth refers to the microscopic texture of a drawing surface that mechanically grips graphite particles, affecting how well pencil marks adhere and how they erase.
Question 2: Which instrument is used to transfer a measurement from one location on a drawing to another without reading the numeric value?
- Compass
- Dividers (Correct answer)
- Protractor
- Engineer's scale
Correct answer: Dividers
Dividers have two sharp points and are used to transfer distances directly between two locations without referencing a numeric measurement.
Question 3: In CAD drafting, what is the equivalent of a physical template used in manual drafting?
- Layer
- Block or symbol library (Correct answer)
- Viewport
- Xref
Correct answer: Block or symbol library
CAD blocks or symbol libraries serve the same purpose as physical templates — they provide pre-drawn standard symbols that can be inserted repeatedly.
Question 4: Which paper weight (in lb bond) is most commonly used for standard engineering drawing sheets?
- 16 lb
- 20 lb (Correct answer)
- 28 lb
- 36 lb
Correct answer: 20 lb
20 lb bond paper is the standard weight for most engineering drawings, providing adequate durability without being unnecessarily heavy for reproduction.
Question 5: A flexible curve (french curve substitute) is best suited for drawing:
- Precise geometric arcs of known radius
- Irregular curves that do not follow a fixed geometric formula (Correct answer)
- Straight lines at precise angles
- Ellipses with specific major and minor axes
Correct answer: Irregular curves that do not follow a fixed geometric formula
Flexible curves can be bent to match any irregular curve shape, making them ideal for drawing non-geometric curves such as topographic contours or streamlined profiles.
Question 6: What is the purpose of drafting dots (small adhesive dots) in manual drafting?
- To mark center points for compass placement
- To temporarily attach drawings or overlays to the drafting board (Correct answer)
- To indicate revision points on a drawing
- To anchor a compass needle without damaging the drawing
Correct answer: To temporarily attach drawings or overlays to the drafting board
Drafting dots are repositionable adhesive circles used to lightly tack drawings or tracing paper to the board without tape damage or residue.
Question 7: Isometric drafting ellipse templates are available in different angles. Which angle represents an ellipse drawn on the top (horizontal) face of an isometric cube?
- 15°
- 30°
- 35°16' (Correct answer)
- 45°
Correct answer: 35°16'
The ellipse representing a circle on the top face of an isometric drawing has a minor-to-major axis relationship corresponding to approximately 35°16' (often rounded to 35°).
CDT Materials & Equipment Knowledge 3
What does the term 'tooth' refer to when describing a drafting surface?