1. Engineering Graphics Stephen W. Crown Ph.D.
Multiview Sketches
Engineering Graphics
Stephen W. Crown Ph.D.

2. Objective
How to use sketching as an effective tool in the engineering design process
How to represent a 3-D object effectively on a 2-D drawing surface (multiview sketching)

3. Overview Sketching Mechanics of sketching Multiview sketches
Definition
Tools / Instruments
Mechanics of sketching
Lines and Curves
A Bounding Box
Multiview sketches
How to create them
When to use them
Why use sketches?
Creativity
Communication
Documentation

4. Sketching
Definition: A rough freehand drawing used to document, communicate, and refine ideas developed in the ideation phase of the design process
Beginners will benefit from instruments
Follows standard practices
A developed skill
Should be the first step of any CAD drawing

5. Tools Pencils Paper Eraser Use a mechanical pencil (0.5mm lead)
Practice using different pressure to produce desired linetypes (construction lines)
Paper
Unlined paper is the most useful
Square grid and tracing paper is often useful
Eraser
A good eraser is worth the investment
Do not overuse your eraser (save some mistakes)

6. Using Simple Instruments
The use of mechanical instruments is recommended only for beginners. Break away from reliance on tools that slow you down.
Helpful tools for beginners
Compass
Triangles
Dividers
Ruler

7. Mechanics of Sketching
Drawing straight lines
Drawing curved lines
Using a bounding box

8. Drawing straight lines
Mark starting and ending point
Break long lines into short line segments by marking the midpoint
Start with a light pass if necessary and then darken
Use a loose comfortable grip
Reorient the paper to your convenience
test your skill with different orientations
an awkward orientation may occasionally produce positive results

9. Drawing curved lines Break large arcs/circles into small segments
Make guide marks for each segment
Circles and Ellipses
Sketch a light square/rectangle
Lightly sketch in diagonals
Mark contact points on square/rectangle
Rotate the paper for each segment

10. Bounding Box and Construction Lines
Plan
choose proper scale and orientation
don’t crowd sketches
Start with a bounding box
Use light straight construction lines
Draw boundary lines of internal features starting with the largest features
Sketch dark object lines using light boundary lines as a guide

11. Multiview Sketching
Represents a 3-D object with a series of 2-D views in contrast to “pictorials” which show all three dimensions in a single view
Also called orthographic projection
Best understood by engineers or technically trained people
Multiview Drawing
Pictorial

12. Parallel projection Preserves true relationship between features
The geometry is generally not distorted
Lines that are parallel on the object are parallel on the drawing
Parallel projectors
The object is projected onto a projection plane as a shadow is projected where the rays form the light source are parallel.
Projection from one view to another is accomplished with parallel projection lines

13. Parallel versus Perspective Projection

14. Projection Planes versus Views
Object formed from projection lines projected perpendicularly onto a projection plane
Planes: Horizontal, frontal, and profile
Each projection plane is perpendicular to adjacent projection planes
Principle views
The object is rotated 90 degrees about the horizontal or vertical axis to give six principle views (top, bottom, front, rear, left, and right side)
Common views: top, front, and right side

15. Only use Necessary Views
One view drawings
Stamped, thin or extruded parts
Specify thickness with a note
Two view drawings
Cylindrical parts
Show the circular and rectangular view
Three view drawings
Usually sufficient for all other drawings
Top, front, and right side view

16. Orientation and Placement of Views
The most descriptive view should be selected as the front view
The natural orientation of the part should be preserved if possible
Views must be aligned
Top view above front view
Right view to the right of front view

17. Hidden lines Represented with dashed lines
Precedence of lines (visible, hidden, center)
Views should be selected to minimize the use of hidden lines most descriptive view should be selected as the front view

18. First Versus Third Angle Projection
Third Angle Projection Associated with English units
First Angle Projection Associated with SI units
ANSI Symbol

19. Fold Lines Represents a 90 degree fold between views
Generally not shown on engineering drawings except when views other than the principle views (auxiliary views) are used.
Labeled as: H/F, F/P, F/1, 1/2

20. Terminology to Relate Views
Adjacent view
A view that is separated by a fold line
The top view is an adjacent view to the front view
Central View
A view that is between two adjacent views
The front view is the central view of the top, front, and right side view
Related views
Two views that are adjacent to a central view
The top and right side view are related views since they are both adjacent to the front view

21. Constructing a New View2
The top and front views of a surface are shown
The fold line represents a 90 degree fold between the views
Parallel projection lines are perpendicular to the fold line 1 3 1 3 2

22. Constructing a New View
A vertical fold line is drawn at an arbitrary distance from the front view
Parallel projection lines are drawn from each vertex
The common depth between the top and side view is used to locate each vertex on the projection lines 1 2 3

23. Sketching as Part of the Creative Design Process
Quickly translate thoughts to paper
An effective means of communication
Stimulates creativity and visualization

24. Sketching Allows for the Quick Translation of Thoughts to Paper
Commit thoughts to paper before you lose an idea
Avoid the of use mechanical tools (drawing tools are helpful for beginners)
Does not need to be an exact representation
objects may be simplified
parts may be missing
Avoid erasing
as new ideas are developed make new sketches
start with light lines and then darken with darker lead or heavier strokes

25. Sketching is An Effective Means of Communication
Understand your audience
Who is looking at the sketches?
What details are they interested in?
What type of sketch will they best understand?
Follow standard practices
You may not always accompany your sketches
Others may misinterpret your drawing
Sketches provide a log of ideas that were considered in a brainstorming session

26. Sketching Stimulates Creativity and Helps Visualization
The process of sketching ideas that are partially developed often aids the design process
do not wait until you have a clear picture before you start sketching
allow yourself the freedom to make mistakes
Visualization of the entire design is essential but often impossible without aid of sketches

27. Appendix
Engineering Graphics

28. Make a Quick Sketch
You will have ten seconds to make a sketch of each object shown below before being asked a few questions about the objects.
How many of the nine views consisted of a square bounding box?
How many of the nine views are the same?
How many of the nine views consisted of only vertical or horizontal lines?
What is the volume of each object (Cube=8 in3)?