CDT Technical Drawing & Blueprint Interpretation 2 — Questions and Answers
Question 1: On a mechanical drawing, what does a phantom line (long-short-short-long) typically represent?
- Hidden internal features
- Alternate positions or repeated detail (Correct answer)
- Center axes of circular features
- Break lines for shortened views
Correct answer: Alternate positions or repeated detail
Phantom lines indicate alternate positions of moving parts, adjacent parts for reference, or repeated detail.
Question 2: A section view labeled 'A-A' corresponds to which cutting-plane line on the primary view?
- Any dashed line in the drawing
- The cutting-plane line labeled with matching letters A-A (Correct answer)
- The first hidden line encountered from left
- A fold line between two views
Correct answer: The cutting-plane line labeled with matching letters A-A
Section view labels match the letters placed at the arrowheads of the corresponding cutting-plane line.
Question 3: What is the correct first-angle projection symbol used to differentiate it from third-angle projection on a drawing?
- A cone with its apex pointing left toward a truncated view (Correct answer)
- A cone with its apex pointing right toward a truncated view
- A sphere inside a rectangle
- Two overlapping circles
Correct answer: A cone with its apex pointing left toward a truncated view
In first-angle projection, the symbol shows the apex of a cone pointing toward the truncated end of the cone (leftward), indicating the European standard.
Question 4: Which line type is used to indicate the boundary of a partial view or a removed section?
- Long-break line
- Short-break line (freehand zigzag) (Correct answer)
- Section line (crosshatch)
- Extension line
Correct answer: Short-break line (freehand zigzag)
Short-break lines (freehand irregular zigzag) indicate where a partial or broken-out section boundary lies.
Question 5: On a blueprint, the note 'TYP' next to a dimension means:
- The feature is a tolerance-yielding part
- The dimension applies to all identical features unless otherwise noted (Correct answer)
- The feature requires a special tolerance
- The part type is unspecified
Correct answer: The dimension applies to all identical features unless otherwise noted
'TYP' (Typical) means the dimension or feature shown applies uniformly to all similar instances on the drawing.
Question 6: In blueprint reading, 'developed length' on a sheet metal part refers to:
- The overall height when folded
- The flat, unfolded length of the part before bending (Correct answer)
- The diagonal measurement across bends
- The perimeter of the finished part
Correct answer: The flat, unfolded length of the part before bending
Developed length is the total flat blank length needed before bending operations are performed on sheet metal.
Question 7: Which auxiliary view is used when an inclined surface does not appear true shape in any principal view?
- Removed section view
- Primary auxiliary view projected perpendicular to the inclined surface (Correct answer)
- Revolved section view
- Half section view
Correct answer: Primary auxiliary view projected perpendicular to the inclined surface
A primary auxiliary view is projected perpendicular to the inclined surface to show its true size and shape.
CDT Technical Drawing & Blueprint Interpretation 2
On a mechanical drawing, what does a phantom line (long-short-short-long) typically represent?