CPM Blueprint Reading and Schematics 2 — Questions and Answers
Question 1: On a mechanical drawing, edges that are not visible from the current view are shown with which line type?
- Short evenly spaced dashes (Correct answer)
- Alternating long and short dashes
- Thick solid line
- Long dash followed by two short dashes
Correct answer: Short evenly spaced dashes
Hidden lines are drawn as short, evenly spaced dashes to show edges that cannot be seen in that view.
Question 2: A line made of alternating long and short dashes running through the middle of a shaft most likely represents what?
- A cutting plane
- A center line marking the axis of symmetry (Correct answer)
- A phantom line for an alternate position
- A break line
Correct answer: A center line marking the axis of symmetry
Center lines use alternating long and short dashes to mark axes of symmetry and centers of holes or shafts.
Question 3: In third-angle projection, the standard used on US drawings, where is the top view placed?
- Below the front view
- To the left of the front view
- Directly above the front view (Correct answer)
- Behind the right-side view
Correct answer: Directly above the front view
Third-angle projection places the top view above the front view and the right-side view to its right.
Question 4: A thick line with arrows at each end, drawn across a view, tells the reader what?
- Where an imaginary cut was made for a section view and which way to look (Correct answer)
- The total length of the part
- Where the part should be welded
- The boundary of a detail view
Correct answer: Where an imaginary cut was made for a section view and which way to look
A cutting-plane line shows where the section was taken, and its arrows show the viewing direction.
Question 5: A part outline drawn with long dashes separated by pairs of short dashes most likely represents what?
- A hidden surface
- An alternate position of a moving part or an adjacent part (Correct answer)
- A dimension extension
- The center of a bolt circle
Correct answer: An alternate position of a moving part or an adjacent part
Phantom lines (long, short, short) show alternate positions, repeated detail, or nearby parts.
Question 6: A drawing's title block shows a scale of 1:2. A feature measures 1.5 inches on the print. What is its actual size?
- 0.75 inch
- 1.5 inches
- 2.0 inches
- 3.0 inches (Correct answer)
Correct answer: 3.0 inches
At 1:2 the drawing is half size, so the actual feature is 1.5 × 2 = 3.0 inches.
Question 7: Why would a drafter add an auxiliary view to a drawing?
- To show the true size and shape of an inclined surface (Correct answer)
- To list the bill of materials
- To show hidden internal threads only
- To show the part at a larger scale
Correct answer: To show the true size and shape of an inclined surface
An auxiliary view is projected perpendicular to an inclined surface so its true size and shape can be seen.