What is a section view?

A sectional view or a section looks inside an object. Sections are used to clarify the interior construction of a part that can not be clearly described by hidden lines in exterior views. By taking an imaginary cut through the object and removing a portion, the inside features may be seen more clearly.

What is this? An ugly rock? Hover your mouse over the image and find out.

Creating a section view.

1. The part is cut using an imaginary cutting plane.
2. The unwanted portion is mentally discarded exposing the interior construction.

Section view example

Lines used in section views.

Cutting Plane Line: Used to show where the object is being cut. (Phantom line type)

Section Lines: Used to indicate where the cutting plane cuts the material. Section lines are thin and the symbols (type of lines) are chosen according to the material of the object. Section lines are generally drawn at a 45° angle.

Rules of Sectioning

Rule 1: A section lined area is always completely bounded by a visible outline.

Rule 2: The section lines in all areas should be parallel. Section lines shown in opposite directions indicate a different part.

Rule 3: All the visible edges behind the cutting plane should be shown.

Rule 4: Hidden features should be omitted in all areas of a section view. Exceptions include threads and broken out sections.

What type of section should I use?

The type of section used depends on the situation and what information needs to be conveyed.

Basic Sections

• Full Section
• Half Section
• Offset Section

Full Section

To create a full section, the cutting plane passes fully through the object. Used in many cases to avoid having to dimension hidden lines.

How does a half section work?

A half section exposes the interior of one half of an object while retaining the exterior of the other half. Half sections are used mainly for symmetric objects or assembly drawings. A centerline is used to separate the two halves. Hidden lines should not be shown on either half.

What is an offset section?

An offset section is produced by bending the cutting plane to show features that don’t lie in the same plane.

What is an offset section?

An offset section is produced by bending the cutting plane to show features that don’t lie in the same plane.