mech 100 – graphics i technical graphics communication: multiview drawings (part 2)
TRANSCRIPT
MECH 100 – Graphics I
Technical Graphics Communication:
Multiview Drawings(Part 2)
Objectives• Quick review and comments on creation of proper
multiview drawings
• Quick review standard line practices used in multiview drawings
• Fundamentals Views of Edges & Planes • Identify normal, inclined, and oblique planes in
multiview drawings
• ANSI Standards for Partial & Revolved Views
Projection Methods & their Attributes:
Perspective versus Parallel
Multiview Drawings:
The Six Principal Views & Angle of Projection
Multiview Orthographic Projection
Imagine Object Suspended in Glass Box
Projections Produce Six Principal Views
Unfolding “Glass Box” to Produce the Six Principal Views of the Drawing
Multiview Drawing of Object
Multiview Drawing of Object(Conventional View Placement)
Central view
Multiview Drawing of Object(Alternate View Arrangement)
Three Space Dimensions: Width, Height, Depth
- Require Multiple Views (at least 2 views) -
Rule 1 Alignment of Features: Every point or feature in one view must be aligned on a parallel projector in any adjacent view
Rule 2 Distances in Related Views: Distances between any two points of a feature in related views must be equal
Three-View Multiview Layout on A-size Sheet
Transferring Depth Dimensions:
- Between TOP & RIGHT views -
Parts Requiring Two-View Drawings
Parts Requiring One-View Drawings
Layout of CAD Model on a Drawing Sheet
Layout of CAD Model on a Drawing Sheet
Layout of CAD Model on a Drawing Sheet
Layout of CAD Model on a Drawing Sheet
Good versus Poor Orientation
Place Object in Natural Position
Use Minimum Number of Views
Use the Most Descriptive Views
First- & Third-Angle of Projection Drawings: The Different Six
Principal Views
Principal Projection Planes and Quadrants: Used to Create First- and Third- Angle Projections
Pictorial Comparison:
First-Angle
and
Third-Angle
Projections
Standard View Arrangements:
Third-Angle (U.S.)
and
(ISO) First-Angle Projections
Third-Angle
First-Angle
View Arrangement:First-Angle Projection
Alphabet of Lines: ASME standard line types for technical drawings
Alphabet of Lines:
Hand Sketched
Engineering Sketch
Showing Several Line Types Used
Various Line Types used in a
Technical Drawing
ASME standard line types for
technical drawings
(dimensions shown for traditional drawing tools)
Drawing Conventions for
Hidden Lines
Precedence of Lines (Review)
Engineering Drawing: Showing
Application of Precedence of
Lines
Application of Center Lines
(for a Cylinder)
Various Applications
of Center Lines
(Conventions)
Fundamental Views of Edges and Planes
Know when the edges or planes are in true size, not foreshortened. Distances, angles, and areas
can then be measured.
Fundamental Views of Edges
Edge line: intersection of two planes & is represented as a line on multiview drawings
Rule 3 True Length & Size: Features are true length or true size when the lines of sight are perpendicular to the feature
Edge line appears as a point in a plane of projection to which it is perpendicularAppears
as a point
Edge line
Edge lines
Fundamental Views of Edges
Inclined line: is parallel to a plane of projection but inclined to the adjacent planes (4 black lines)
Oblique line: is not parallel to any principal plane of projection. It never appears as a point or in true length in any of the six principal views (line 1 – 2)
Fundamental Views of Surfaces
Surface A: principal plane // to frontal plane
Surface B: principal plane // to horizontal plane
Surface C: principal plane // to profile plane
Surface D: inclined plane (edge view in front view)
Surface E: oblique plane (not parallel nor on edge in any principal planes)
Rule 4 Foreshortening: Features are foreshortened when the lines of sight are not perpendicular to the feature
Rule of Configuration of PlanesRule 5 Configuration of Planes: Areas that are the same feature will always be similar in configuration from one view to the next, unless viewed on edge
Rule 6 Parallel Features: Parallel features will always appear parallel in all views
Rule 7 Edge Views: Surfaces that are parallel to the lines of sight will appear as lines or edge views
Analysis by Surfaces (of Multiview Drawings)
Rule 6 Parallel Features: Parallel features will always appear parallel in all views
Rule 7 Edge Views: Surfaces that are parallel to the lines of sight will appear as lines or edge views
Technique used to visualize 3-D objects from multiview drawings
Rule 5 Configuration of Planes: Areas that are the same feature will always be similar in configuration from one view to the next, unless viewed on edge
Rule 8 Contiguous Areas: No two contiguous areas can lie in the same plane
(If they were in the same plane a line would not be drawn to separate them)
Analysis by Surfaces (of Multiview Drawings)
Technique used to visualize 3-D objects from multiview drawings
Rule 8 Contiguous Areas: No two contiguous areas can lie in the same plane
(If they were in the same plane a line would not be drawn to separate them)
Analysis by Surfaces (of Multiview Drawings)
Technique used to visualize 3-D objects from multiview drawings
Angles in Multiview Drawings
(C) A 90-degree angle can be measured in a foreshortened surface if one edge is true length. (A) Angles other than 90 degrees can only be measured in views where the surface that contains the angle is perpendicular to the line of sight. (B) Not true angle shown in drawing
Representing Limiting Elements
The sides of the triangle represent limiting elements of the cone.
The vertical sides of the rectangle represent the limiting elements of the sides of the cylinder.
Tangent & Non-tangent Partial Cylinder
Note: When the transition of a rounded end to another feature is not tangent, a line is used at the intersection of the two features
Elliptical Representation of a Circle
An elliptical view of a circle is created when the circle is viewed at an oblique angle
Viewing Angles for Ellipses
Note: The size (or exposure) of an ellipse is determined by the angle of the line of sight relative to the circle
Multiview Drawings of Solid Primitive Shapes
Representation of Types of Machined Holes
See textbook (Ch. 10) for technical drawing representations of fillets, rounds, finished surfaces, chamfers, intersecting cylinders with prisms and other features.
ANSI Standards for Multiview Drawings
Partial Views and Revolution Conventions
Partial View for A Symmetrical Object(also for some types of auxiliary views & for saving time)
Use of Partial Views to Eliminate Hidden Lines
Improves clarity
Front View
Revolution Conventions for Ribs and Webs
Violates true projection of views
Revolution Conventions for Objects with Bolt Circles
Violates true projection of views
Revolution Convention for Representation of Arms
Violates true projection of views
Assignment
• Review: Chapter 10 – Multiview Drawings
• Study: Chapter 17 – Dimensioning Practices
• Answer Review Questions on Bb Learn (Chapter 10 – Part 2)