Lecture 4: Sections

Question 1

Why are sections used?

Answer 1

To see internal features that are not visible in projections.

Question 2

Cutting plane

Answer 2

An imaginary plane by which the object is cut to see the inside. Written as a dashed line with arrows showing which side is being cut.

Question 3

How to draw a section

Answer 3

1. Choose a cutting plane and direction best suited to the object’s internal features.
2. Draw the cutting plane on the original object.
3. Draw a front view parallel to the cutting plane.
4. Draw section lines.
5. Name the sectional view.

Question 4

Section lines

Answer 4

Drawn on exposed surfaces. For a single material, a hatch pattern is used.

Question 5

Section types (6)

Answer 5

1. Full
2. Half
3. Offset
4. Broken out
5. Revolved
6. Aligned

Question 6

Full section

Answer 6

Cutting plane divides the whole object

Question 7

Half section

Answer 7

Cutting plane divides half the object while keeping the other side intact. The center line must be indicated. Used for symmetrical objects.

Question 8

Offset section

Answer 8

Cutting plane is not a straight line. Bends in the cutting plane are not shown in the drawing. used to show unaligned internal features.

Question 9

Broken out section

Answer 9

Freestyle cutting plane. Used to show internal details that look best when broken apart.

Question 10

Revolved section

Answer 10

Cross sections perpendicular to the object and superimposed onto the orthographic view. Used for when an object’s profile changes.

Question 11

Aligned/angled Section

Answer 11

Used on circular objects (EX: ceiling fan), angled cutting plane lines to include more features in a section view (like an offset cutting plane line but not 90 degrees)