Thursday, October 28 th 2004
ENGR 111 9.2

Learning Objectives
 List and recognize by name; symbol; and ANSI number these materials:
- Cast Iron - Aluminum - Brass, Bronze,
- Steel - Zinc or Copper
 Identify a drawing as being a:
- Full Section - Offset Section - Revolved Section
- Half Section - Broken-Out Section - Removed Section
 Given an orthographic view; draw section views:
- In Pencil or - In AutoCAD
 Use revolutions and partial views (as conventional practices) to construct sectional views of an object.
 List the parts of a drawing which do not get crosshatched, even if the cutting plane passes through them.
 Sketch a cutting plane for any of the sections listed above

R eadiness
A ssessment
T est
9.2.1
 Individually answer the following questions. You will be given 2 minutes:

R eadiness
A ssessment
T est
9.2.1
 Individually answer the following questions. You will be given 2 minutes:
 List 4 types of sectional views.

Team Discussion Item
 As a team, discussing the following question:
 What is the purpose of sectional views?

Purpose of Sections
 Show internal detail
 Replace complex orthographic views
 Describe materials in an assembly
 Depict assembly of parts

Sectioning Practices
 Different parts at different angles
 Hatch spacing of about 1/16”-1/8”
 Cutting plane line .020” wide (bold)
 Section or hatch lines -thin .007”
 Visible lines -wide .015”
 Not parallel or perpendicular to boundary

Sectioning Practices
 When sectioning an assembly of several parts, draw section lines at varying angles to distinguish separate parts.

Most common
ANSI Material Patterns
ANSI No. Name Pattern
 ANSI 31 -- Cast Iron, General
 ANSI 32 -- Steel
 ANSI 33 -- Brass, Bronze,
Copper
 ANSI 38 -- Magnesium,
Aluminum
 Earth

What is ANSI?
.

Available Hatch Patterns in
AutoCAD

Cutting Plane
 The sight arrows at the end of the cutting plane are always perpendicular to the cutting plane.
 Line thickness of the cutting plane is the same as the visible object line.
 The direction of the arrow indicates the line of sight.
CUTTING PLANE LINE

Types of Sections……..Fig #:
 Brokenout section……………6.3
 Conventional breaks………….6.4
 Full section……………………..6.5
 Half section……………………..6.8
 Revolved section……………..6.10
 Removed section……………..6.11
 Offset section………………....6.12
(See Essentials of Engineering Design Graphics by Vinson for figure references)

Full Section
 Cutting plane passes through entire object
 Hidden lines are omitted
 Visible lines
“behind” the cutting plane must be shown

Individual Exercise (7 min)
● Sketch a full section of the object shown below

Individual Exercise (7 min)
● Were you correct ?
● What material (hatch pattern) did you use?

CUTTING PLANE LINE Half section:

HALF SECTION
 Half of view is cross-hatched
 ALL hidden lines may be omitted
 Center line divides halves
 Center line remains only if associated feature is sectioned

CUTTING PLANE LINE Offset section:
 Bend the cutting plane to show more features

CUTTING PLANE LINE Offset section:
 Sectional view does not denote location of offset

Revolved section:
 Show cross- sections by rotating sections 90 o
The section view stays on the object.
Without breaks
With breaks

Removed section:
 Removed sections are offset from the object.
R.05
SECT D-D
SECT E-E
.2 (4) .92
.82
E F
SECT F-F
E F

Broken out section:
 Used to section a small portion of the object
 Does not modify the rest of the view

Conventional Practices
 Conventional practices are accepted drawing techniques that violate the rules of orthographic projection
 They are designed to simplify orthographic drawing of complex features.

Aligned Parts:
Arms Lugs

Aligned Parts:
Single Arm
Ribs & Holes

Parts Not Sectioned.
 Don’t crosshatch (even though the cutting plane may pass thru them):
– Ribs, webs, spokes
– Thin parts like gaskets
– Ball bearings, roller bearings
– Most vendor items:
 Bolts  Washers  Shafts
 Nuts  Screws  Pins

Partial Views
 Use partial views to conserve space
 Which half depends on whether you section the view or not.

Conventional breaks:
…….For extremely large parts
SCROLL SYMBOL LIGHTING BOLT
SOLID SHAFT
HOLLOW PIPE
CYLINDRICAL BREAKS SHORT BREAK LINES

Crosshatching 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.

Pair Homework Assignment
 Drawings (in AutoCAD):
– 28 all
– 29 all
– 32 a, b, c
– 34 all
 Due: Beginning of class 10.2

Stop