CDT Technical Drawing & Blueprint Interpretation 3 — Questions and Answers
Question 1: What does a centerline (alternating long and short dashes) indicate when applied to a circular feature?
- The hidden outline of the circle
- The axis or center of symmetry of the circular feature (Correct answer)
- The cutting plane through the circle
- The tangent edge of a curved surface
Correct answer: The axis or center of symmetry of the circular feature
Centerlines mark the axis of symmetry, center of circles, paths of motion, or pitch circles of gears.
Question 2: On a drawing with the note 'SCALE 1:2', an object drawn 50 mm long represents an actual size of:
- 25 mm
- 50 mm
- 100 mm (Correct answer)
- 200 mm
Correct answer: 100 mm
A 1:2 scale means the drawing is half actual size, so 50 mm on paper equals 100 mm in reality.
Question 3: Which type of sectional view shows only half the object in section and half in exterior view, separated by a centerline?
- Full section
- Offset section
- Half section (Correct answer)
- Revolved section
Correct answer: Half section
A half section cuts only one quarter of the object, revealing interior on one side and exterior on the other, divided by the centerline.
Question 4: In GD&T, the symbol for flatness tolerance is:
- A circle with a horizontal line through it
- Two parallel horizontal lines (Correct answer)
- A diagonal line with arrowheads
- A rectangle enclosing a circle
Correct answer: Two parallel horizontal lines
The flatness symbol is two parallel horizontal lines, indicating that a surface must lie within two parallel planes separated by the tolerance value.
Question 5: An isometric drawing differs from a perspective drawing primarily because:
- Isometric uses only two axes while perspective uses three
- Isometric lines remain parallel and do not converge to vanishing points (Correct answer)
- Isometric drawings show true shape on all faces
- Isometric views require auxiliary views for inclined surfaces
Correct answer: Isometric lines remain parallel and do not converge to vanishing points
In isometric drawings, parallel edges remain parallel and are drawn at true scale, whereas perspective drawings converge toward vanishing points.
Question 6: On a wiring or electrical schematic blueprint, dashed lines between components typically represent:
- High-voltage connections
- Mechanical linkage or enclosure boundaries (Correct answer)
- Ground connections
- Alternate circuit paths
Correct answer: Mechanical linkage or enclosure boundaries
Dashed rectangles or lines on electrical schematics usually indicate mechanical enclosures, panels, or linkages — not electrical connections.
Question 7: What does the abbreviation 'MAX' beside a dimension indicate on a technical drawing?
- The dimension is a nominal reference value
- The feature must not exceed the stated value (Correct answer)
- The feature must equal the stated value exactly
- The dimension requires a maximum material condition modifier
Correct answer: The feature must not exceed the stated value
'MAX' means the feature size or dimension must not exceed the given value, setting an upper limit.
CDT Technical Drawing & Blueprint Interpretation 3
What does a centerline (alternating long and short dashes) indicate when applied to a circular feature?