Lesson
17:
Engineering Specifications and Gear ProfileGears
#6-7
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modeled
and animated by Mark Gatewood 2005
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Engineering Drafting is explored by the use of ACAD
2002. The above simple model and the following 3 models
that follow are examples of 3rd Angle Projection,
which is the projection technique used in the United
States. Refer to page 94 and 95 of your text to understand
1st and 3rd Angle Projection.
In these four lessons we will be involving the fundamentals
of orthographic views and the creation of an Isometric
representation of the model that is being explored.
The above animation represents the model rotating
on an axis which displays the useful view or the working
view of the model.It is positioned in perspective
view not isometric view.
In Engineering Drafting you will understand that
creating a part using isometric and orthographic representation
means that the part can be measured, the various aspects
of the model can be measured accurately.
The Base Bracket is a common part which has 2 mounting
holes and 2 vertical slots where another machine part
can be achored and adjusted by this slot.
Connecting Your Learning
As you work your way through this lesson, you should
reflect on the following questions:
What is the function of a base bracket?
How is the front side and top views determined in
the base bracket?
What an isometric model is and its symmetry?
Why is it important that all useful views are represented
in orthographic's ?
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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
-
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 and dimension
according to ASME14.5 using ACAD 2002.
2. Identify the isometric angles used to create isometric
views (30, 90 and 150 degrees)
3. Understand how to use the commands of : line, copy,
move, the @ command and vectoring,
4. Draw an Isometric view from orthographic views.
5. Center orthographic models in paper space using 1.5"
between views.
6. Identify the working view of a model and its front,
top and side views.
Key
Terms
"click
on the key on any of these terms and it will hyperlink
to the course glossary" |
The first model
you will be drawing is called the base bracket and below
is enough of a dimensioned model to draw the orthographic
views. The top view is missing in this drawing and will
need to be added. With the information below you will draw
in ACAD 2002 the 3 useful views of the following model full
scale. Please Insert Media Disk Engineering 3145 Lesson
1 into the D drive of your computer.
*Note: The Lessons are best
viewed with real player and you can download the latest
version by clicking on the words
real
player.
The following is what your completed orthographic's
of the Base Bracket should look like before submission.
The
following screen capture shows half scale orthographic's
and a full scale Isometric of the Base Bracket. This picture
is an example of what your completed assignment should look
in drawing space.
*Note: The Lessons are best
viewed with real player and you can download the latest
version by clicking on the words
real
player.
After completing
each lesson attach your drawing to an email and send to your
Instructor:losimilar@yahoo.com
or if you are taking this course in the classroom Print your
assignment and pass it in to be graded.
Your
Text Book and Reading Assignments
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Text:
Engineering Drawing and Design
by Jensen and Helsel
Use
this text as a reference together with the media disks that
you are using for the Semester. If you are a classroom student
media is available on either of 3 Servers.
Lesson 17 assessment comprises:
-
Lesson 17a submitted as a dwg file (10
pts.)
-
Lesson 17b 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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