1. OrthroGraphic View Dwgs-1
Engineering 22
OrthroGraphic View Dwgs-1
Bruce Mayer, PE
Licensed Electrical & Mechanical Engineer

2. Learning Goals
How to Unfold the “Glass” Box to draw Perpendicular Projection (OrthoGraphic) Views
Determine the Minimum No. of Views Needed to Fully Describe an Object
Properly Place Views Relative to Each Other
Which Views show Which Combination of the Object’s H, W, & D

3. Learning Goals cont
Understand the Criteria for Selecting the CENTRAL View
Apply the Guidelines for the Proper Use of Hidden Lines
Determine When Lines/Shapes are in TRUE Length/Shape as opposed to FOREshortened
Construct MultiView Orthographic Projection Drawings

4. OrthoGraphic View Drawing
All Objects Are Three Dimensional (3-D)
Height, Width, and Depth
Drawings are done on a 2-D surface
Multiview Sketching (Orthographic Projection) Represents A 3-D Object With A Series Of 2-D Views
Best Understood By Technical People
In Contrast To “Pictorials” Which Show Three Dimensions In A Single View

5. Projection Planes Versus Views
Objects are Formed From Parallel “Sight Lines” Projected Perpendicularly Onto A Projection Plane
Horizontal, Frontal, Profile
Each Projection Plane Is Perpendicular To the Adjacent Projection Planes
Lines/Features Parallel to Proj Plane are TRUE Length/Size

6. Principle Views
The Object Is Rotated 90° About The Horizontal Or Vertical Axis To Yield the Six Principle Views
Top, Bottom, Front, Rear, Left & Right Side
Common views:
Top
Front
Right Side

7. View Selection
Only Use The Views That Are Needed To Represent The Object
One view drawings
Stamped part: Specify uniform thickness with a note
Two view drawings
A Cylindrical Part
Three view drawings
Usually Sufficient For All Other Objects
Top, Front, And Right-Side Views

8. General Guidelines
The Most DESCRIPTIVE View Should Be The FRONT, or CENTRAL, View
Views MUST Be ALIGNED
Top View ABOVE Front View
Right-Side View To The RIGHT Of Front View
Hidden lines
Represented With Dashed Lines
Precedence of lines (Visible, Hidden, Center)
Views Should Be Selected To MINIMIZE The Use Of HIDDEN LINES

9. Parallel Projection Preserves true relationship between features
Parallel lines are drawn parallel
The geometry is generally not distorted
Parallel projectors
Light from a point-source at an -distance

10. The Glass Box
Projection Planes Placed Parallel to the Principle Faces of an Object Form a Glass Box
What An Observer Would See From the OUTSIDE Looking IN

11. Unfolding The Glass Box
Hinge the Four Intersections on The Frontal Plane And “Flatten Out” the Box
Maintains the TRUE-Length Of Lines Parallel to the Viewing Planes
The 5 Hinge Lines are Known as FOLDING Lines

12. The Unfolded Glass Box

13. Common Dimensions
Every 3-D Object Can Be Described By its Height, Width, and Depth
The Views from the Glass Box Share These Dimensions in This Form

14. Central View = Front View
Criteria for Selecting Central View
Front View Shows The Shape Of The Object MOST Clearly
Chose Front View So That It Has A Large Number Of Normal () Surfaces
Minimize Hidden Lines
Show The Object In A Usual Or Operating Position
i.e., Do NOT show the Object “UpSide Down”

15. The Primary Views

16. Producing a Multiview Drawing
Select Front View As Before
Align View Bounding Boxes
i.e., Block-In Views
Approx. Center on Drawing Border
Draw Features Using Instruments/CAD
True Shapes Remain
Project Between Views
Use 45° “Mitre” Lines to Xfer Depth Dims
Label Vertices if Needed

17. Align Bounding Boxes TOP FRONT RIGHT WIDTH DEPTH WIDTH DEPTH
Miter line at 45°
HEIGHT
HEIGHT
FRONT
RIGHT

18. Construction Lines to Xfer Dims
TOP
Use 45° Miter Line to Transfer Dims Between Top & Side View
FRONT
RIGHT

19. Label Vertices A B C A B C A B C ,A B C
An Intermediate Step to Aid Construction
Only If needed to Clarify Positions For the Designer A B C ,A B C

20. Views FULLY Aligned
Very FEW Hidden Lines

21. True Length Vs. Foreshortened
Only Lines/Planes that Are PARALLEL to the Projection Plane are (LoS  Plane) show in TRUE LENGTH/SHAPE
Others are ForeShortened in the View

22. Hidden Line Usage
Hidden Lines can Greatly-CLARIFY or Greatly-CONFUSE a Drawing View
Visible Lines are Usually Easy
Exceptions = Fillets & Rounded Edges
Creating Useful Hidden Lines Requires
Judgment
Adherence to Convention

23. Draw Hidden Lines Dashes are 2X to 3X Longer Than Spaces
.e.g.; Dashes 1/8” (3mm) Long, Spaces 1/16” (1.5mm) Long.
Should Intersect Neatly Except Where A Line Of A Different Linetype Would Appear To Be Extended
“Jump” Visible Lines That They Cross
Closely Spaced Parallel Hidden Lines Are Drawn With The Dashes STAGGERED if Possible

24. Conventions for Hidden Lines
Hidden lines should join neatly with visible lines except when it causes a visible line to be extended. When two different lines join to form a single line, leave a gap on the less important line.
Hidden lines should join neatly to form “T” or “L” shaped inter- sections.
Hidden lines should jump visible lines that they do not intersect.
It is permissible for a hidden line to cross a visible line.

25. More Hidden Line Conventions
Stagger the dashes on closely spaced parallel hidden lines.
Hidden line dashes should intersect neatly to from clear corners, as in the bottom of this drilled hole.
Intersecting hidden lines should form neat corners, as in this countersunk hole.

26. Curved Hidden Lines
Curved hidden lines should not extend a visible curve in the same direction. Leave a gap on the hidden line so that you can easily see where the visible line ends.
Curved hidden lines dashes should extend to the point of tangency. Don’t end with a gap at the point of tangency. It makes it hard to see the location.

27. Hidden Lines Hidden Lines Can be Made A number of ways in AutoCAD
Draw Line in a LAYER with Hidden Form
Draw a SOLID Line, then CHANGE to a Hidden LAYER (Described Last Lecture)
Draw a SOLID Line, then CHANGE to a Hidden LINETYPE using PROPERTIES ToolBar
Draw a SOLID Line, then CHANGE to a Hidden LINETYPE using PROPERTIES Side-Menu

28. Chg Hidden-Line by ToolBar
Want
Select HIDDEN
Select Line to Light-Up Handles
Click on “Layer Control” Box to PullDown LineTypes Menu
Deactivate Grips by Hitting Esc

29. Chg Hid-Ln by Properties Menu
Want
Rt-Click Line or Grips to Activate the Context PullDown Menu
Select properties
Double-Click an END Grip
Select Line to Light-Up Handles
Activate the Properties Side Menus by one of

30. Chg Hid-Ln by Properties Menu
On Properties Side Menu Activate the LineType PullDown
Select Hidden and Deactivate Grip by Hitting Esc
NOTE
The Prop-ToolBar or Prop-Menu Can also Change Line Color, and Thickness

31. Visualization: Ortho → 3D
For a Practicing Engineer with Detail-Design Assistance, READING Projection Drawings Is as Important as MAKING them
The Practicing Engineer Must be Able to Think in 3-D Using 2-D Projections
i.e., To Visualize a 3-D Object Given Front, Top and Side Views
This is Inverse of Creating Views from the 3-D Object

32. Visualization Aids Using Labels on Multiview Drawings1 S 1 S 3 3
Using Labels on Multiview Drawings
Label surfaces; e.g.,
Label surfaces; e.g., S
Label vertices; e.g., 1,3

33. Visualization Continued
Recognize Similar Shapes in Different Views
Equal number of sides
Parallel edges
Best Way to “Read” Engineering Drawings is the “Writing” of Great Numbers of them

34. Eliminate Unnecessary Views
Show Only The Views Needed Drawing To Fully Define The Shape Of The Object
Choose The Views Which Show The Shapes Of The Features Most Clearly
The Right Side View Is Preferred To The Left Side View If They Show The Object Equally Well
The Top View Is Preferred To The Bottom View If They Show The Object Equally Well
Showing Only The Necessary Views Saves Time, Makes The Drawing Less Cluttered, And Makes It Easier To Interpret

35. Try 0.7mm MechPencil w/ HB or B Lead
All Done for Today
Try 0.7mm MechPencil w/ HB or B Lead
".. indeed, far and away the most prolific writer in the history of the subject" writes Howard Eves in An Introduction to the History of Mathematics. Euler's contribution to mathematics is represented here by a few of the notations conventionalized by him or in his honor. Around the world, these are read, written, and spoken thousands of times every day:
e for the base of the natural logarithm (a.k.a. "the calculus number") a, b, c for the sidelengths of a triangle ABC f(x) for functional value R and r for the circumradius and inradius of a triangle sin x and cos x for values of the sine and cosine functions i for the imaginary unit, the "square root of -1" capital sigma for summation. capital delta for finite difference.
Euler grew up near Basel, Switzerland, and studied at an early age under Johann Bernoulli. He finished studies at the University of Basel when only 15 years old. From 1727 to 1741, Euler worked in St. Perersburg, Russia, and then moved to the Akademie in Berlin. In 1766 he returned to St. Petersburg, where he remained.

36. Licensed Electrical & Mechanical Engineer BMayer@ChabotCollege.edu
Engr/Math/Physics 25
Appendix 
Time For
Live Demo
Bruce Mayer, PE
Licensed Electrical & Mechanical Engineer

37. Recall Std Lines
Visible line
Hidden line
Hatching
Centerline
Dimension
Extension
Leader
Cutting Plane
Viewing Plane
Short break
Long break
Phantom
Stitch
Chain
Line Patterns Communicate What The Line Represents In The Drawing
Line Patterns Tell You Information Such As Whether The Line Is Hidden, Visible, Or A Centerline
Line Precedence:
Visible → Hidden → Center

38. Hidden Line Example Block-In sizes 2 6 FView → 15W x 7H
TView → 15W x 6D
RView → 7H x 6D 6 11 2 Ø2 3 3 4 4 3 3 4 8 3 11
1Hx2D Groove, Ctr’d

39. OrthoGraphic View Sketching
Block-In Views Using Approximately True-Length Dimensions
Engr-Comp-Pad Grid is Useful for Scaling
Block-In all Details Such as Corners, Notches, Circles, etc.
Dim All Construction Lines with Eraser
Darken All Final Lines to Emphasize Object in All Views