MEM 201
Fundamentals of Computer Aided Design
Sectional Orthographic Views
Dept of Mechanical Engineering and Mechanics, Drexel University
Today’s Learning Objectives…
• Need for Sectional View
• Contents of Sectional view
• Identifying different kinds of sectional views.
• Sectional View Guidelines and good practices.
• Cross Hatching in AutoCAD.
Dept of Mechanical Engineering and Mechanics, Drexel University
Sectional Views
• These are views that show internal features such
as cuts, holes, step cuts as orthographic views.
Dept of Mechanical Engineering and Mechanics, Drexel University
Sectional Views
Dept of Mechanical Engineering and Mechanics, Drexel University
Purpose of Sectional Drawings
• Depict assembly of parts.
• Show internal detail.
• Replace complex orthographic views.
• Describe materials in an assembly.
Dept of Mechanical Engineering and Mechanics, Drexel University
Contents of a Sectional View
• Sectional views have:
– Cutting plane shown as edge view: cutting plane line.
– Cutting plane arrow representing the direction of line of sight.
– Section lines (hatch) shows where areas of solid material are
present.
A
Dept of Mechanical Engineering and Mechanics, Drexel University
A
Different Kinds of Sectional Views
•
•
•
•
Full Section
Half Section
Offset Section
Aligned Section
Dept of Mechanical Engineering and Mechanics, Drexel University
Full Sectional View
• Cutting plane cuts fully through object.
• No Hidden Lines are shown.
• Visible Lines behind the cutting plane must be shown.
Dept of Mechanical Engineering and Mechanics, Drexel University
Half Sectional View
• Cutting plane passes halfway through object.
• Used for symmetric parts.
• Omit hidden lines.
Dept of Mechanical Engineering and Mechanics, Drexel University
Offset Sectional View
• Cutting plane line not straight but offset to pass
through important features.
• Don’t show cut formed by offset.
Dept of Mechanical Engineering and Mechanics, Drexel University
Aligned Sectional View
• Align sections cut at an angle (for circular shapes).
• Features may be projected onto plane for clarity.
Dept of Mechanical Engineering and Mechanics, Drexel University
Good Sectional View Drawing Practices
• Different parts at different angles or patterns
• Hatch spacing of about 1/16”-1/8”
• Cutting plane line .020” wide (bold)
• Section or hatch lines -- thin .007”
• Visible lines -- width .015”
• Do not show Hidden lines.
• Direction 45° – not parallel or perpendicular to boundary
A
• Name them on the side.
Section A-A
Dept of Mechanical Engineering and Mechanics, Drexel University
A
Position of Sectional Drawings
Dept of Mechanical Engineering and Mechanics, Drexel University
Sectioning of Holes
Dept of Mechanical Engineering and Mechanics, Drexel University
Cross Hatching in AutoCAD
• AutoCAD can apply a given pattern to fill an area.
• The area must be a closed area.
• To fill the area use the BHATCH command.
Dept of Mechanical Engineering and Mechanics, Drexel University
In AutoCAD….
Dept of Mechanical Engineering and Mechanics, Drexel University
Standard Material Patterns
• The
ANSI
patterns
represent the more standard
engineering materials.
• ANSI31 is the generic
material which can be used
in no material is specified.
Dept of Mechanical Engineering and Mechanics, Drexel University
Predefined Pattern Library
Dept of Mechanical Engineering and Mechanics, Drexel University
Questions
?
Note: A 20min quiz of Orthographic Views, Sectional
Views will follow next week.
Dept of Mechanical Engineering and Mechanics, Drexel University