1. IENG 248: Orthographic, Multi-view Projections
Lecture 03
IENG 248:
Orthographic, Multi-view Projections
4/23/2017
Engineering Graphics & 3-D Modeling

2. Computer Lab work starts Thursday! Engineering Graphics & 3-D Modeling
Load SolidWorks & Test SolidWorks
See link on Materials page for 2015 version
Copy & run the “workarounds” from your desktop
Takes about 1 hour (if nothing else running)
Test Installation by starting Tutorials
Re-install (repair installation) if necessary
May only be used from Campus IP addresses
M, W, F: 1:00 – 5:30 PM IER 308/310 for help
Can VPN into SDSM&T to run from off-campus site
Computer Lab work starts Thursday!
Lab project will require teamwork, so start to form person teams:
Sit in teams by table pods for class (share )
Share texts by table pods when doing HW / Labs
4/23/2017
Engineering Graphics & 3-D Modeling

3. Engineering Graphics & 3-D Modeling
Assignments
Lab 01: Due 24 SEP
Open SolidWorks, Open the Tutorials
Perform the Introduction to SolidWorks (~ 1 hr)
Print the model, staple & turn in with a cover page
HW 3: Due in One Week
Turn in the following on EP with a cover sheet
Sketch the symbol for a third angle projection
Complete HO 5.5 and HO 5.6 on the photocopies
Draw the following Projects (p.152) two per page:
# 3, 4, 16, and 22 (note: numbers are below object)
Draw the following Projects (p.154) two per page:
# 6, and 11 (note: numbers are below object)
4/23/2017
Engineering Graphics & 3-D Modeling

4. Orthographic Projection
a system of drawing views of an object using perpendicular projectors from the object to a plane of projection
4/23/2017
Engineering Graphics & 3-D Modeling

5. Projection of an Object
A projection is a single view of an object
Imagine tracing the image of an object on a sheet of glass with a pen
If the projection rays are perpendicular to the glass, the view is orthographic
4/23/2017
Engineering Graphics & 3-D Modeling

6. Engineering Graphics & 3-D Modeling
The Glass Box
To get to a Multi-view drawing:
Imagine encasing the object within a glass box and tracing the outline on each face
Note that there are 90o between each adjacent face
4/23/2017
Engineering Graphics & 3-D Modeling

7. Unfolding the Glass box
To locate the six standard views
Imagine that the walls of the box are hinged and unfold the views outward around the front view.
4/23/2017
Engineering Graphics & 3-D Modeling

8. Standard Views - (3rd Angle)
Unfolding the box flat locates the projections
Each of the six views aligns with the adjacent views
4/23/2017
Engineering Graphics & 3-D Modeling

9. Engineering Graphics & 3-D Modeling
Locating Side Views
An alternative position for a side view is to rotate it and align it with the top view
Note that there is still a 90o fold between the top and side view in the alternative position
4/23/2017
Engineering Graphics & 3-D Modeling

10. Engineering Graphics & 3-D Modeling
Projection Systems
Third Angle Projection:
Is the arrangement of standard views used in the U.S., Canada, and Mexico.
For this system, imagine the planes of glass being between the viewer and the object - so one traces the outline, then opens planes flat.
First Angle Projection:
Is the arrangement of standard views used in the E.U., and most Asian countries.
For this system, imagine that the object is between the viewer and the plane of glass - so one draws around the object edges like a template, then opens the planes out flat.
4/23/2017
Engineering Graphics & 3-D Modeling

11. First Angle Projection
For 1st Angle projections then:
The right side view is located left of the front view,
The top view is located below the front view, … etc.
To distinguish between projection systems, a standard symbol is used
4/23/2017
Engineering Graphics & 3-D Modeling

12. Symbols for 1st & 3rd Angle Projection
The symbol is a simple front & right side view of a truncated cone
The front of the cone is always viewed head-on (target-like)
So for 1st Angle projections, the profile view is located to the left, …
and for the 3rd Angle projections, the profile is on the right
4/23/2017
Engineering Graphics & 3-D Modeling

13. Transferring Dimensions
The depth of a projection should be the same in both the Top and Side views
One method to keep the depth proportional is to measure from a parallel reference (like the folding line), and transfer the distance to the vertices from one view to the other.
Folding lines are considered a form of construction line
4/23/2017
Engineering Graphics & 3-D Modeling

14. Transferring Dimensions - Miter Lines
Dimensions can also be projected across a miter line - a four step process that does not require measurements…
Draw a miter line at 45 degrees, located at a convenient distance to produce the desired view.
4/23/2017
Engineering Graphics & 3-D Modeling

15. Transferring Dimensions - Miter Lines
Sketch light lines projecting depth locations for points to the miter line…
…and then down into the side view
(as shown).
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Engineering Graphics & 3-D Modeling

16. Transferring Dimensions - Miter Lines
Project additional points…
surface by surface…
and project the corresponding surfaces
from the adjacent view… to locate each intersection
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Engineering Graphics & 3-D Modeling

17. Transferring Dimensions - Miter Lines
Then draw the view by connecting the ‘dots” – each vertex of a surface projection
and a miter line projection – using visible lines.
4/23/2017
Engineering Graphics & 3-D Modeling

18. Engineering Graphics & 3-D Modeling
Hidden Lines
are similar to the visible lines of a drawing, but have a different pattern
are used to show the intersections of surfaces that are not directly visible from the direction of sight
each view in a drawing shows the entire object (including hidden & center lines) as seen from that viewing direction
4/23/2017
Engineering Graphics & 3-D Modeling

19. 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.
4/23/2017
Engineering Graphics & 3-D Modeling

20. More Conventions for Hidden Lines
Stagger the dashes on closely spaced parallel hidden lines.
Hidden line dashes should intersect neatly at clear corners, as in the bottom of this drilled hole.
Intersecting hidden lines should form neat corners, as in this countersunk hole.
4/23/2017
Engineering Graphics & 3-D Modeling

21. Conventions for 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.
4/23/2017
Engineering Graphics & 3-D Modeling

22. Engineering Graphics & 3-D Modeling
Choice of View
orient the object so that the front view shows the shape of the object most clearly (fewest hidden lines)
chose front view so that it has a large number of normal surfaces.
show the object in the usual or operating position
show the right side view & top views unless other views are better (fewer hidden lines)
4/23/2017
Engineering Graphics & 3-D Modeling

23. Engineering Graphics & 3-D Modeling
Necessary Views
A sketch or drawing should only contain the views needed to clearly and completely describe the object.
Choose the views that show the shape most clearly, have the fewest hidden lines, and show the object in a usual, stable, or operating position.
One view drawing
of a shim (thin, flat)
One view drawing
of a connecting rod
4/23/2017
Engineering Graphics & 3-D Modeling

24. Remember the part in the Glass Box?
IF DRAWING ALL SIX STANDARD VIEWS …
… we imagined unfolding the walls of the hinged glass box outward around the front view …
4/23/2017
Engineering Graphics & 3-D Modeling

25. Remember the part in the Glass Box?
… but we don’t need all six standard views!
Which of the views below are necessary? X X X
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Engineering Graphics & 3-D Modeling

26. Engineering Graphics & 3-D Modeling
Partial Views
When the entire view is not necessary to show the object clearly you can use a partial view.
Use a break line to limit the partial view as shown in (a), (b), and (d) below.
For symmetrical parts, you can draw a half-view on one side of the centerline as shown in (c).
4/23/2017
Engineering Graphics & 3-D Modeling

27. Engineering Graphics & 3-D Modeling
Right & Left Hand Parts
Many parts are used in pairs where opposite parts are mirror-images of one another. A left-hand part is not just a right hand part turned around. It has to be manufactured differently from a right hand part. In order to save time, a single drawing can be used for both a left and right handed part by noting on the drawing such as:
“LH PART SHOWN, RH OPPOSITE”.
4/23/2017
Engineering Graphics & 3-D Modeling

28. Engineering Graphics & 3-D Modeling
Summary
The six standard views are often thought of as being produced from an unfolded glass box.
Distances can be transferred or projected from one view to another.
Only the views necessary to fully describe the object should be drawn.
4/23/2017
Engineering Graphics & 3-D Modeling

29. Summary: Necessary Views
Show only the views needed to fully define the shape of the object.
Choose the views which show the shapes of the features 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.
4/23/2017
Engineering Graphics & 3-D Modeling