mech 100 – graphics i technical graphics communication: multiview drawings (part 2)

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)