Unit 5 Sectional Views
The purpose of a section is to show interior detail or space. By means of a limited number of carefully selected views, the external features of the most complicated designs can be fully described. However, we often need to show interiors that cannot be illustrated clearly by hidden lines. We show such interiors by slicing through the object much as we cut through an apple or melon. A cutaway view of the part is then drawn; such views are called sectional views, cross sections, or simply sections.
To produce a sectional view, a cutting plane is assumed to pass through the part. The cutting plane is then removed, and the two halves are drawn apart, exposing the interior construction. In which case, the direction of sight is towards one half of the object. The other half is then mentally discarded.
Drafters use sectional views to improve the clarity of complex objects when internal surfaces result in too many hidden lines. Special conventions are used to make a sectional view easy to understand. Creating a sectional view with CAD can be a complicated operation. Understanding thoroughly the concepts of sectional views will help the drafter create the drawing with the CAD software.
Unit Objectives
005.
Demonstrate the correct techniques for preparing sectional views
005.01
Explain the concepts and principles of sectional views
005.02
Construct sectional views
Sections
A. The purpose of a section view is to show interior detail or space of an object or entity.
B. There are multiple types of Section views:
1. Full Section
2. Half Section
3.Broken out
4. Revolved or Rotated
5. Remove
6. Offset
7. Aligned
C. Identify Cutting Plane Lines :
1. Cutting plane lines are used to indicate where the section or cut is made.
2. Arrowheads on a cutting plane line indicate the direction of sight.
3. The two most commonly used cutting plane lines are:
a. A heavy line of altering long dashes (3/4" to 1 ½") with a pair of short dashes (1/8") long.
b. Uniform length dashes (¼") with uniform spacing between.