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Lesson
12: Drawing the Slotted Sector in Ortho, Iso and 3d |
FIG. 12a (the Slotted Sector)
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In lesson 12 you will be drawing the slotted sector,
which is a challenging model because you will have
to create multiple regions that have to be extruded
and subtracted from one another.
This particular model is found where another object
rotates, such as a shaft and the orientation of the
rotating shaft can be adjusted through a slotted area
in the sector itself.
The slotted sector and parts that are constructed
in a similar fashion and perform similar functions
can be found in door handle assemblies in automobiles,
bell cranks in aircraft ailerons, flaps and elevators,
to name but a few.
If Mechanical engineering is your interest allot
of these simple and not so simple models have been
engineered and will continue to be re-engineered as
new devices that serve similar functions are designed.
Only two views are necessary to describe this model
and in this particular lesson we will use the side
view not illustrated as a sectional but illustrated
with hidden lines instead of hatched regioned areas.
Connecting Your Learning
As you work your way through this lesson, you should
reflect on the following questions:
How did the slotted sector get its name?
What is an ellipse and how is it used in this model?
What is a region and what are the conditions for the
extrusion to a 3d model from a region?
How will the slotted sector model be created in 3d?
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The State of Arizona has assembled Drafting
standards to make sure that Instruction is thorough
and well thought out by the instructor. By clicking
on the hyperlink below will upload to your browser window
the entirety of these standards. The standards that
are addressed in this lesson are below the hyperlink.
1.0 USE BOARD DRAFTING EQUIPMENT,
INSTRUMENTS AND MEDIA.
2.0 DEMONSTRATE SKETCHING, LETTERING,
AND LINE SKILLS.
- 2.1 Demonstrate freehand sketching skills for drafting
applications.
- 2.2 Demonstrate lettering skills.
- 2.3 Demonstrate line work.
6.0 DEMONSTRATE GEOMETRIC CONSTRUCTIONS
- 6.1 Measure Geometric Constructions.
- 6.2 Develop Geometric Constructions.
8.0 APPLY BOARD DRAFTING SKILLS TO COMPUTER-AIDED
DESIGN/DRAFTING (CADD)
- 8.1 Demonstrate computer skills for a CADD system.
- 8.2 Create dimensional CADD entities.
- 8.3 Create 3 dimensional CADD drawings.
The State of Arizona has also assembled Math
standards and many of these apply directly to
the vocational subject area of Drafting. Drafting
is a very precise discipline and the use of mathematics
is integral to design and manufacturing. Below are
the math standards that are involved in this lesson
1M-P1. Compare and contrast
the real number system and its various subsystems
with
regard to their structural characteristics
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PO 2. Compare subsets of the
real number system with regard to their properties
(commutative, associative, distributive, identity,
inverse and closure properties)
1M-P2. Construct, interpret and
demonstrate meaning for real numbers and absolute
- PO 3. Solve real-world distance problems using
absolute value
- PO 4. Determine, among the solutions to a real-world
problem, which, if any, is reasonable
- PO 2. Define absolute value as the distance from
the origin
4M-P1. Interpret and draw three-dimensional
objects
- PO 1. Sketch prisms, pyramids, cones, cylinders
and spheres
- PO 2. Classify prisms, pyramids, cones, cylinders
and spheres by base shape and lateral surface shape.
- PO 3. Recognize the three-dimensional figure represented
by a two-dimensional drawing.
- PO 5. Make a model of a three-dimensional figure
from a two-dimensional drawing and make a two-dimensional
representation of a three-dimensional object (models
and representations include scale drawings, perspective
drawings, blueprints or computer simulations)
4M-P4. Deduce properties of,
and relationships between, figures from given
assumptions
- PO 1. Find similarities and differences among
geometric shapes and designs using a given attribute
(e.g., height, area, perimeter, diagonals and angle
measurements)
- PO 2. Identify arcs, chords, tangents and secants
of a circle
- PO 3. State valid conclusions using given geometric
definitions, postulates and theorems
- PO 4. Represent pi as the ratio of circumference
to diameter
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Lesson
Objectives
By the end of this lesson you should be
able to:
1. Draw the orthographic views of the
slotted sector and dimension the model.
2. Identify the isometric angles used to create isometric
views (30, 90 and 150 degrees)
3. Create an oblique view using the front view of the
slotted sector.
4. Adjust the dimscale overall and linear to reflect
full scale dimensions in the ortho/iso drawing.
5. Create the 3d model of the slotted sector from the
top orthographic view.
6. Working with colors and line rendering for visualization
enhancement.
7. Using 2 views to illustrate a model. "Minimum
views to describe a Part"
8. Create and locate the accurate use of center lines
in orthographic drawings.
9. Be able to distinguish when a model line takes precedence
over a hidden line.
Key
Terms
"click
on the key on any of these terms and it will hyperlink
to the course glossary" |
The 12th
model you will be drawing is called the slotted sector
and it is a model where only the front and top view are
necessary to completely illustrate the model and its attributes.
The illustration of the slotted sector orthographically
involves 3 circles that are used as arcs to create its
initial front view. The side view of this model is illustrated
with hidden and center lines. Notice the double set of
hidden lines at the top of the slot in its side view.
Insert your
Lesson 12 media disk into your CD drive and begin listening
to the avi file: lesson 12a. You can open up both software
programs: ACAD and your media player at the same time
and toggle back and forth between screens, and be able
to draw and listen simultaneously.
Below is
an example of what your completed drawing should look
like. Pay attention to details so you can obtain all your
points for this assignment. It is always better to get
it right the first time, especially when you have what
the finished product should look like. I will mention
in the media files about the Dim-scale of the dimension
text.
The next part of Lesson 12b you will be creating the
Oblique view of the slotted sector.
Creating an oblique in ACAD or on a drafting table is
quite easy when you have a little experience with creating
a model. We will be staying with a full scale side view
illustrated as a full sectional. An oblique will be creaed
from the front view.
Please Insert the Media Disk and listen to lesson 12b.
Below is what your completed assignment should look like
when finished.
Please Insert the Media Disk labeled Lesson
12 into your CD drive of your computer and begin listening
how to draw the 3d model of the slotted sector The lesson
avi is titled Lesson 12c and below is an example of a completed
accurate model of the Slotted Sector. You will submit your
drawing in South East Isometric. This is what your completed
3d assignment should looks like.
*Note:
The Lessons are best viewed with real player, or Windows
Media Player 9 for 2000 Professional and Version 10 for
XP.
After
completing each lesson attach your drawing to an email and
send to your Instructor's email.
email:
losimilar@yahoo.com
Your
Text Book and Reading Assignments
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Text:
Autocad Drafting by
Grout, Resetarits and James
Use
this text as a reference to the media disks that you
are using for the Semester.
Lesson 12 assessment comprises:
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Lesson 12a submitted as a dwg. file
(10 pts.)
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Lesson 12b submitted as a dwg. file.(10
pts.)
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Lesson 12c submitted as a dwg. file.(10
Pts.)
Rubrics for Grading: The drafting
standards for assessing the quality and accuracy of your
drawings are as follows: Neatness, Accuracy and Lines and
Lettering. One half of one point (.5) will be taking off
your score in relation to NALL.
Submit by email attachment all of
the above lessons as dwg. files and send to your Instructor
whose mail address is. losimilar@yahoo.com
Your Instructor will grade your drawings
within 24 hours and email you back the grade/assessment
of your work. You should take allot of pride in your work.
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