Çankaya University Journal of Science and Engineering
Volume 14, No. 1 (2017) 042-098
Assessment of the Use of AutoCAD in
Mechanical Engineering Technical Drawing
Education
Turgut Akyürek,
Department Mechanical Engineering, Çankaya University, Ankara, Turkey,
e-mail: turgutakyurek@cankaya.edu.tr
Abstract: AutoCAD is one of the widely used software tools in engineering education. In this study, a
general assessment of AutoCAD for the usage in the mechanical engineering technical drawing education
is made. AutoCAD is assessed in terms of the fulfilment of the requirements defined for the main two
technical drawing courses. AutoCAD is assessed in terms of its capability in meeting the requirements of
the technical drawing courses.
Keywords: AutoCAD, assessment, technical drawing, education, mechanical engineering.
1. Introduction
In general, there are mainly two technical drawing courses within the context of the
mechanical engineering education. These courses are generally given using commercially
available software, such as AutoCAD [1], Catia [2], DataCAD [3], DraftSight [4], Inventor
[5], KeyCreator Direct CAD (former CADKEY) [6], NX (former Unigraphics) [7],
OpenSCAD [8], Pro/Engineer [9], Solid Edge [10], Solid Works [11], Turbo-CAD [12] and
VariCAD [13]. The first of the Computer Aided Drawing/Design (CAD) courses deals with
basics of engineering drawing and focusses on part drawing (CAD I), while the second course
(CAD II) captures assembly drawing and descriptive geometry. On the other hand, most of the
Computer Aided Engineering (CAE) software used in engineering education requires
knowledge of solid modelling, which is covered by CAD I and CAD II. It is common to use a
CAD software for these purposes, and AutoCAD [1] is one of the widely used software tools
within this context.
ISSN 2564 – 7954 © 2017 Çankaya University
CUJSE 14, No. 1 (2017)
43
In this study, the AutoCAD Mechanical (2013) software – a version of AutoCAD with some
features specialized in mechanical engineering - is assessed for the use in mechanical
engineering technical drawing education. This study is not a benchmarking for comparing
CAD software tools in mechanical engineering education, but focuses on the assessment of
the usage of AutoCAD, which is considered as the most widely used software for engineering
education.
2. Methodology
In this study, a three-step approach has been used.
Step 1 – Define contents of the CAD courses,
Step 2 – Determine requirements for each content,
Step 3 – Assess the capability of AutoCAD Mechanical in implementing each requirement.
2.1. Step 1 – Defining Contents of the CAD Courses
In defining the CAD I and CAD II course contents, contents of technical drawing courses
ME113 Computer Aided Engineering Drawing I and ME114 Computer Aided Engineering
Drawing II that are given to mechanical engineering students of Çankaya University have
been used as a basis. The contents are given in syllabi of the courses [14,15] and summarized
in TABLE 1.
The CAD I and CAD II courses of Cankaya University were established in 2011, after a
comprehensive survey of many international and national universities’ CAD courses. A
comparison of the course contents of some of the selected international and national
universities is summarized in
Table 2 and TABLE 3 for the CAD I and CAD II courses, respectively. Considering the
comparison tables, the contents could be regarded as a basis for the assessment study and as
samples representing the general CAD I and CAD II course contents, rather than belonging to
the courses of a single university/department.
TABLE 1. Contents of CAD I and CAD II Courses
Number CAD I
CAD II
1
Basics of engineering drawing
Introduction to solid modelling
2
Coordinate systems
Construction of solid features
3
Basic geometric elements
Tolerances, surface quality marks
44
T. Akyürek
4
Drawing simple geometric objects and
Geometric dimensioning and tolerancing
editing
5
Solid modelling fundamentals
Working drawing and assemblies
6
Projection theory/multi-views from 3-D
Threaded fasteners
7
Projection of 3rd view from others
Non-threaded fasteners, springs
8
Pictorial projection
Mechanisms
9
Section view
Welding
10
Dimensioning and tolerancing
Descriptive geometry
11
Basics of assembly drawing
12
Presentation of engineering
drawings/printing
TABLE 2. A Comparison of the CAD I Course Contents of Some Universities.
Number CAD I Course Content
Course Content of the University’s
Mechanical Engineering Department
1
Basics of engineering drawing
1* 2
+ +
3
+
4
+
5
+
6
+
7
+
8
+
9 10
+ +
2
Coordinate systems
+
+
+
+
+
+
+
+
+
+
3
Basic geometric elements
+
+
+
+
+
+
+
+
+
+
4
Drawing simple geometric objects and +
editing
+
+
+
+
+
+
+
+
+
5
Solid modelling fundamentals
+
-
-
+
+
-
-
-
+
-
6
Projection theory/multi-views from 3-D +
+
+
+
+
+
+
+
+
+
7
Projection of 3rd view from others
+
+
+
+
+
+
+
+
+
+
8
Pictorial projection
+
+
+
+
+
+
+
+
+
+
9
Section view
+
+
+
+
+
+
+
+
+
+
10
Dimensioning and tolerancing
+
+
+
+
+
+
+
+
+
+
11
Basics of assembly drawing
+
+
+
+
-
+
-
-
+
-
12
Presentation of engineering
drawings/printing
+
+
+
+
+
+
+
+
+
+
*Numbers represent: 1- Cankaya, 2-UC, Berkeley, 3-Cambridge, 4-Carnegie Melon, 5-Gazi,
6-ITU, 7-IYTE, 8-METU, 9-Stanford, 10-YTU universities.
CUJSE 14, No. 1 (2017)
45
TABLE 3. A Comparison of the CAD II Course Contents of Some Universities.
Number CAD II Course Content
Course Content of the University’s
Mechanical Engineering Department
1
Introduction to solid modelling
1*
+
2
+
3
+
4
+
5
+
6
+
7
+
8
+
2
Construction of solid features
+
+
+
+
+
+
+
+
3
Tolerances, surface quality marks
+
+
+
+
+
+
+
+
4
Geometric dimensioning and
tolerancing
+
+
+
+
+
+
+
+
5
Working drawing and assemblies
+
+
+
+
+
+
+
+
6
Threaded fasteners
+
+
+
+
+
+
+
+
7
Non-threaded fasteners, springs
+
+
+
+
+
+
+
+
8
Mechanisms
+
+
+
+
+
+
+
+
9
Welding
+
+
+
+
+
+
+
+
10
Descriptive geometry
+
-
-
+
-
-
+
-
*Numbers represent: 1- Cankaya, 2-UC, Berkeley, 3-Carnegie Melon, 4-Gazi, 5-ITU, 6IYTE, 7-METU, 8-YTU universities.
The contents of the courses are given at least in two levels. TABLE 1 shows only the first level
of contents. An example of the second level is given in TABLE 4 for ‘Drawing Simple
Geometric Objects and Editing’.
TABLE 4. Second Level of Contents for Simple Geometric Objects and Editing
Number
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
4.13
4.14
4.15
4.16
4.17
Content
Drawing a rectangle
Drawing a circle
Drawing tangent lines or arcs
Drawing an arc
Drawing an ellipse
Drawing an involute
Drawing regular polygons
Creating a copy of an object
Creating a mirror copy of an object
Creating a resized copy of an object at a distance
Trimming unnecessary portions of a drawing
Extending incomplete lines
Changing size of an object
Chamfering or filleting
Creating array of an object
Moving and rotating an object
Undoing, re-doing, erasing, zooming
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T. Akyürek
2.2. Step 2 – Determining Requirements for Contents of the CAD Courses
For each content, the requirements that mechanical engineering students should achieve are
determined. As an example, requirements for the content ‘simple geometric objects and
editing’ in CAD I is given in TABLE 5.
TABLE 5. Requirements for Simple Geometric Objects and Editing
Number
R4.1
R4.2
R4.3
R4.4
R4.5
R4.6
R4.7
R4.8
R4.9
R4.10
R4.11
R4.12
R4.13
R4.14
R4.15
R4.16
R4.17
Requirement
Draw a rectangle
Draw a circle
Draw an arc
Draw lines or arcs which are tangent to two circles or lines
Draw an ellipse
Draw an involute
Draw equilateral polygons
Create a single or multiple copy of an object
Create a mirror copy of an object
Create a resized copy of an object at a defined distance
Trim unnecessary portions of a drawing
Extend incomplete lines until a boundary item
Change size of an object
Chamfer or fillet the sharp edges of an object
Create array of an object in rectangular or polar form
Move an object and rotate at an angle
Undo, re-do, erase, zoom
There are 104 and 73 requirements for CAD I and CAD II, respectively.
2.3. Step 3 – Assessing Capability of AutoCAD Mechanical in Implementing
Each Requirement
AutoCAD Mechanical is assessed on a ‘1 or 0’ basis by reviewing whether it does or does not
meet each requirement. If the assessment is partial ‘1’ and partial ‘0’, the requirement is
fragmented so that the result is either ‘1’ or ‘0’.
For example, in assessing AutoCAD Mechanical for the requirements of unit system, the
requirement ‘Metric, US Customary or any other unit for length and angle can be defined or
be changed at any time’ is rated as 1, which indicates that AutoCAD Mechanical meets the
requirement. The assessment is not the subjective view of the assessor. It shows only whether
students can or cannot implement the requirement by using AutoCAD Mechanical.
The assessment of AutoCAD Mechanical is done for the CAD I and CAD II courses
separately.
CUJSE 14, No. 1 (2017)
47
3. Results and Discussion
3.1. Assessment of AutoCAD Mechanical in Terms of Fulfillment of the
Requirements of a CAD I course
The main subjects of the course, the requirements, and assessment of AutoCAD Mechanical
in meeting the requirements are given below. Numbered items define the main subjects of the
course, while R and A stand for the requirements in that area and assessment of AutoCAD
Mechanical in fulfilling the requirement, respectively. The score ‘1 or 0’ is given at the end of
each assessment. The score ‘1 and 0’ imply that AutoCAD Mechanical does or does not fulfil
the requirement.
3.1.1. Basics of Engineering Drawing
R1.1. Determine units for drawing
A1.1. Metric, US Customary or any other unit for length and angle can be defined or be
changed at any time. In AutoCAD, there are three ways to implement a drawing action,
namely writing a command, selecting a menu item or clicking on the related toolbar icon, and
then following instructions of the program (1).
R1.2. Establish a layout page
A1.2. Layout page is required to take a printout of the drawing. For each drawing in the model
space, many layout pages with different paper sizes, units, scales and title blocks can be
created using the templates of AutoCAD or established by the user.
R1.2.1. Determine paper size
A1.2.1. The paper size may change with the units used, complexity of the drawing, and the
standards adopted. Templates can be prepared for different purposes and paper sizes, and then
a convenient template can be selected for a new layout (1).
R1.2.2. Determine drawing scale
A1.2.2. The scale used in the model space is 1:1. A different scale may be used to fit the
drawing in the layout page. The scale will change with the page size (1).
R1.2.3. Develop title block
A1.2.3. AutoCAD has some title block templates. These templates are not proper for
professional use. However, users can create their own title block templates which will be in
line with ISO, ANSI or any international standard (1).
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T. Akyürek
R1.3 Prepare a template
A1.3. AutoCAD has many templates for different uses. Any available template can also be
used or new templates can be created with a previously defined setup. All the parameters such
as unit, limits of drawing area, grid size, snap spacing, layout templates can be defined in the
templates (1).
3.1.2. Coordinate Systems
R2.1. Define a coordinate system
A2.1. A cartesian or polar coordinate system can be used in the world coordinate system or
user (local) coordinate system. Depending on the information available, absolute or relative
coordinate values can be used. Relative coordinates are very practical, and can be used with
either Cartesian or Polar coordinates.
R2.1.1. Locate a point by using Cartesian absolute coordinate values
A2.1.1. A point can be located by inputting absolute Cartesian coordinate values in the world
or local coordinate system (1).
R2.1.2. Locate a point by using Cartesian relative coordinate values
A2.1.2. A point can be located by inputting relative Cartesian coordinate values in the world
or local coordinate system (1).
R2.1.3. Locate a point by using polar absolute coordinate values
A2.1.3. A point can be located by inputting absolute polar coordinate values in the world or
local coordinate system (1).
R2.1.4. Locate a point by using polar relative coordinate values
A2.1.4. A point can be located by inputting relative polar coordinate values in the world or
local coordinate system (1).
3.1.3. Basic Geometric Elements
R3.1. Draw a point
A3.1. Point command, clicking on point icon or selecting the point menu item requires
coordinates of the point, inputting the coordinates through writing coordinate values or
clicking on the desired location (1).
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R3.2. Create a grid system
A3.2. The grid system of pattern of dots is easy to create. It helps the user in aligning objects
and measuring the distances between the grid dots. Grid spacing can be changed. The grid
system can be turned on or off. Grid snapping is a very useful tool in drawing a defined sized
element. Snapping restricts the motion of the cross hair to the defined grid spacing intervals.
The orientation of the grid axes can be rotated (1).
R3.3. Draw a line
A3.3. A line can be drawn easily using different ways. It may be a finite line, ray or infinite
line. Line conditions such as being parallel, perpendicular, tangent or intersecting is easy to
define. Basic types of lines such as visible line, hidden line, center line, dimension line,
extension line, cutting-plane line, phantom line can be drawn easily with AutoCAD,
especially with AutoCAD Mechanical. Basic types of lines are shown in FIGURE 1.
FIGURE 1. Basic line types.
R3.3.1. Draw a line by using Cartesian coordinate system
A3.3.1. Using a relative coordinate system is easier and more practical than an absolute
coordinate system. After inputting the starting point coordinate values, the line can be drawn
50
T. Akyürek
by inputting 𝛥x, 𝛥y, 𝛥z values of the next point with respect to the previous point (1).
R3.3.2. Draw a line by using the polar coordinate system
A3.3.2. The polar relative coordinate system is default in AutoCAD Mechanical. After
clicking on the first point location, the line is drawn by inputting distance and angle of the
second point with respect to the first (1).
R3.4. Arrange precedence of lines
A3.4. Lines which are at the same location can be arranged in the order as visible line, hidden
line and center line (1).
R3.5. Draw polylines in different forms
A3.5. The polyline tool is a very flexible and useful tool combining different portions of lines
as a single object, which can be split later. Changing width and shape of the line is possible as
shown in FIGURE 2. Line types can be changed with the ‘pedit’ command. There is a mix of
some line definitions: AutoCAD has two options for spline, namely ‘spline-fit points’ which is
identical to mathematical spline, and ‘spline-control vertices’ which is similar to a Bezier
curve.
FIGURE 2. Polyline example.
R3.5.1. Draw a line as a polyline
A3.5.1. It is the same as drawing a line. The difference is that all the lines in polyline are
treated as a single object, and there is no need to use the ‘region’ command to create a surface
before creating a 3-D model (1).
R3.5.2. Draw an arc as a polyline
A3.5.2. It is the same as drawing an arc. In polyline, arc is a part of polyline and treated as a
single object (1).
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3.1.4. Drawing Simple Geometric Objects and Editing
R4.1. Draw a rectangle
A4.1. Rectangles can be drawn with various line widths, with normal, chamfered or filleted
corners as shown in FIGURE 3 (1).
FIGURE 3. Rectangle types.
R4.2. Draw a circle
A4.2. Drawing a circle by using different ways depending on the available data is possible. It
might be circumscribed about or inscribed in a polygon. It might be concentric or eccentric.
AutoCAD provides six options to draw a circle: center point-radius, center point-diameter, 2
point, 3 point, tangent-tangent-radius, and tangent-tangent-tangent. An example of tangenttangent-radius circle application is given in FIGURE 4 (1).
FIGURE 4. Tangent-tangent-radius circle application.
R4.3. Draw an arc
A4.3. Arcs can be drawn using different combinations of center, end point, start point, radius,
angle, length, and direction data (1).
52
T. Akyürek
R4.4. Draw lines or arcs which are tangent to two circles or lines
A4.4. AutoCAD provides convenient object snap for finding tangency so that drawing a line
tangent to two circles, an arc tangent to one or two lines or arcs is a simple process.
R4.4.1. Draw a line which is tangent to an arc or circle
A4.4.1. A tangent line is drawn by inputting the first point location, then going over the circle
or arc, and clicking at the location where the tangency sign appears (1).
R4.4.2. Draw an arc or circle which is tangent to the other two circles or arcs
A4.4.2. It can be drawn by for example drawing a circle using tangent-tangent-radius option
(1).
R4.5. Draw an ellipse
A4.5. There are three options in drawing an ellipse, namely axis end point, center, and arc. An
example with center option is shown in FIGURE 5 (1).
FIGURE 5. An ellipse with center option.
R4.6. Draw an involute
A4.6. Involute – the path of a point on a string as the string unwinds from a line, polygon, or
circle as shown in FIGURE 6- can be drawn using tangencies and snapping (1).
FIGURE 6. Involute examples.
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R4.7. Draw equilateral polygons
A4.7. Regular polygons such as the ones given in FIGURE 7 can easily be drawn using the
options of center or edge, and inscribed in or circumscribed about a circle (1).
FIGURE 7. Regular polygons.
R4.8. Create a single or multiple copy of an object
A4.8. Objects can be copied as many as required at the desired locations (1).
R4.9. Create a mirror copy of an object
A4.9. An object having symmetry can be created through mirror copying of its quarter or half
as shown in FIGURE 8 (1).
FIGURE 8. Mirror copying example.
R4.10. Create a resized copy of an object at a defined distance
A4.10. AutoCAD creates the resized copies at the defined distance easily using ‘offset’
command as shown in FIGURE 9 (1).
54
T. Akyürek
FIGURE 9. Offset examples.
R4.11. Trim unnecessary portions of a drawing
A4.11. Trimming and deleting unrequired portions of a drawing can easily be done as shown
in FIGURE 10 (1).
FIGURE 10. An example of trimming.
R4.12. Extend incomplete lines until a boundary item
A4.12. Lines can be extended up to a defined object feature using ‘extend’ command as
shown in FIGURE 11 (1).
CUJSE 14, No. 1 (2017)
55
FIGURE 11. An example of extend.
R4.13. Change size of an object
A4.13. There are many ways to change the size, such as changing the value in the properties
table, using ‘lengthen’ or ‘stretch’ command, or changing scale with a scale factor (1).
R4.14. Chamfer or fillet the sharp edges of an object
A4.14. Sharp corners can be truncated or rounded.
R4.14.1. Chamfer the sharp vertices
A4.14.1. Chamfering can be done using ‘two distances’ or ‘a distance and angle’ options (1).
R4.14.2. Round the sharp vertices
A4.14.2. By using ‘fillet’ command and defining a radius, a sharp edge can be rounded easily
(1).
R4.15. Create array of an object in rectangular or polar form or along a path
A4.15. Multiple copies of an object can be created using rectangular or polar array commands
as shown in FIGURE 12. It is also possible to multiply an object along a curved path. Basic
features can be arranged and be changed at any time.
56
T. Akyürek
FIGURE 12. Example of rectangular and polar arrays.
R4.15.1. Create an array of an object in rectangular form
A4.15.1. After creating a base view to be multiplied, it can be arranged in linear array form by
defining the number of rows, distance between rows, number of columns and the distance
between the columns (1).
R4.15.2. Create an array of an object in polar form
A4.15.2. After creating a base view to be multiplied, it can be arranged in polar array form by
defining the center of array, number of items and angle of rotation (1).
R4.15.3. Create an array of an object about a curved path
A4.15.3. After creating a base view to be multiplied, it can be multiplied about a curved path.
Number of objects and distances between the array elements can be defined (1).
R4.16. Move an object and rotate at an angle
A4.16. Objects can be moved to a desired location and be rotated about a point at a defined
angle in counter clockwise or clockwise direction like the one given in FIGURE 13 (1).
FIGURE 13. Rotating an object at an angle.
CUJSE 14, No. 1 (2017)
57
R4.17. Undo, re-do, erase, zoom
A4.17. By using the basic handling tools, any number of actions can be taken back or redone,
view of the drawing can be zoomed in or out. Any portion of the drawing can easily be
deleted (1).
3.1.5. Solid Modeling Fundamentals
R5.1. Create primitive solid models
A5.1. Primitive solids such as box, cone, cylinder, torus, wedge, pyramid, and sphere can be
created easily by inputting the required data (1).
R5.2. Create a complex solid by using extrusion technique.
A5.2. Extrude tool can be used along a complex path, or perpendicular/inclined line at an
angle path. An example is given in FIGURE 14 (1).
FIGURE 14. Use of extrude tool.
R5.3. Create a complex solid by using revolving technique
A5.3. Revolve tool can be used in creating objects with axial symmetry. An example drawing
is shown in FIGURE 15 (1).
58
T. Akyürek
FIGURE 15. Use of revolve tool [16].
R5.4. Create a complex solid by using sweeping technique
A5.4. The sweep tool can used to create complex solid models. For example, sweeping a
defined profile along a helix may create a spring model or teeth model of a bolt or screw. An
example is shown in FIGURE 16 (1).
FIGURE 16. Use of sweep tool.
R5.5. Create a complex solid by using lofting technique
A5.5. Loft tool can be used to draw very complex solid models. An example is given in
FIGURE 17 (1).
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59
FIGURE 17. Use of loft tool.
R5.6. Create a solid model by Constructive Geometry Solid Modelling
A5.6. Solid models of complex geometric objects can be created using basic geometric forms
and Boolean operators. An example showing the steps of creating the object is given in
FIGURE 18 (1).
FIGURE 18. Constructive Geometry Solid Modelling Example.
R5.7. Create solid model of an object using Boolean operators
A5.7. Boolean operators, namely union, subtraction, and intersection, can be effectively used
in creating new complex objects from comparatively simple objects like the one shown in
FIGURE 19. Exclusive-or (XOR) option is not available in AutoCAD.
60
T. Akyürek
FIGURE 19. Use of Boolean operators [17].
R5.7.1. Create solid model by using Boolean ‘union’ operation
A5.7.1. A new complex model can be created from two separate parts by adding the parts,
using union command (1).
R5.7.2. Create solid model by using Boolean ‘subtraction’ operation
A5.7.2. A new complex model can be created from two separate parts by subtracting one from
the other, using subtract command (1).
R5.7.3. Create solid model by using Boolean ‘intersection’ operation
A5.7.3. A new complex model can be created from two separate parts by keeping intersecting
portions, using intersect command (1).
R5.7.4. Create solid model by using Boolean ‘Exclusive or (XOR)’ operation
A5.7.4. XOR is a combination of Boolean operations ‘union’ and intersection. In the
intersection operation common portions of the two parts are reserved. In XOR operation, the
deleted portion of the two parts after application of intersection operation is reserved. It is the
union minus the intersection of two parts. That command is not available with AutoCAD (0).
R5.8. Create Constraint Based solid models
A5.8. Constraint based (parametric) modelling in 2-D can be used effectively. Changing the
parameters changes the drawing automatically while keeping the constraints. Two examples
are given in FIGURE 20. Parametric modelling in 3-D is not possible.
CUJSE 14, No. 1 (2017)
61
FIGURE 20. Constraint based modelling example for 2-D.
R5.8.1. Create solid models by using parametric 2-D models
A5.8.1. AutoCAD is very flexible in defining parametric constrains on any plane.
After changing the parameters, new sketch file to be used in creating solid model is
generated automatically without a need to redraw the 2-D profile (1).
R5.8.2. Create solid models by using parametric 2-D models
A5.8.2. AutoCAD is not intended for 3-D modelling, and Autodesk, who is the owner
of AutoCAD provides the software Inventor for this purpose. AutoCAD does not keep
the sketch which is used to create a 3-D model. When the 3-D model is created, the
sketch is converted to 3-D model and no sketch is contained in the 3-D model data,
but it is kept in the 3-D model data by the solid modelling software such as Inventor
of Autodesk. For example, the 3-D parametric design shown in FIGURE 21 is not
possible with AutoCAD, since AutoCAD provides only 2-D parametric capability.
Any feature in the 3rd dimension cannot be defined as a parameter of the features
created in the 2-D sketch plane. After generating a 3-D model, the defined parameters
are cancelled and the parametric model is converted to a 3-D model which has no
parametric data. A standard part or assembly in different sizes is easy with 3-D
parametric design, which can be created by changing only the values of the
parameters. In AutoCAD a different size of a product should be re-drawn. This feature
is more important in mating parts of an assembly, since any configuration change in
one part requires related changes in the other parts. This can be achieved easily
through 3-D parametric modelling. Absence of this feature is a deficiency of
AutoCAD (0).
62
T. Akyürek
FIGURE 21: Parametric modeling in 3-D [18].
R5.9. Create 3-D models by using sweeping techniques
A5.9. Sweeping a plane (generatrix) along a path (diretrix) creates complex solid geometries,
and using Boolean operations may yield to the desired very complex solid model. An example
is given in FIGURE 22. Before creating the solid model, the generatrix should be drawn on the
proper working plane. Working plane can be defined using different techniques such as using
user coordinate system or object snapping utility. Setting UCSFOLLOW to 1 provides
working in 2-D instead of 3-D space (1).
FIGURE 22. Steps of creating a solid model using sweeping and Boolean operations [19].
CUJSE 14, No. 1 (2017)
63
R5.10. Duplicate solid part features.
A5.10. Solid parts can be duplicated using linear and radial arrays like the one given in
FIGURE 23. Creating array of holes requires subtracting (1).
FIGURE 23. Linear and polar array application [20].
R5.11. Obtain volume related properties from the drawing
A5.11. Volume related properties such as volume, mass, moments of inertia, and centroid
cannot be obtained from the solid model (0).
R5.12. Use different options for rendering a model
A5.12. AutoCAD has many options in rendering a model, such as 2D wireframe, conceptual,
hidden, realistic, shaded, shaded with edges, shades of grades, sketchy, wireframe, and x-ray.
Some rendering options are shown in FIGURE 24 (1).
FIGURE 24. Rendering options.
R5.13. Get the solid models of standard parts from the content library
A5.13. AutoCAD is not intended to create solid models although it has basic tools for creating
solid geometries. AutoCAD has 2-D multi-views of standard parts. However, a library of solid
models of standard parts with optional sizes is not available (0).
3.1.6. Projection Theory/Projection of Multi-views from 3-D Models
R6.1. Create multi-views from 3-D model and keep them associative
A6.1. Creating multi-views from 3-D model is possible. Changes in the model are reflected to
layout page automatically, but reverse is not possible, i.e. model-multiview data associativity
is unidirectional as shown in FIGURE 25.
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FIGURE 25. Model-data associativity [19].
R6.1.1. Create multi-views from 3-D model and keep solid model-drawing data associative
A6.1.1. Creating multi-views from 3-D model is possible. Any change in solid model is
automatically reflected to multi-views created in layout page (1).
R6.1.2. Keep drawing data - model associative
A6.1.2. After creating multi-views from 3-D model, changing the solid model through
modifying multi-views in layout page is not possible with AutoCAD Mechanical (0).
R6.2. Create perspective and isometric projections
A6.2. One-point perspective, and isometric projection can be obtained from 3-D model
automatically. Principal views can be obtained for both third-angle projection and first-angle
projection as shown in FIGURE 26 (1).
FIGURE 26. Third-angle projection and first-angle projection [21].
3.1.7. Projection of Third Principal View from Other Views/Auxiliary View
R7.1. Align the principal views
A7.1. Three principal views can be aligned by using object snapping, miter line and
construction lines as shown in FIGURE 27 (1).
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FIGURE 27. Alignment of principal views.
R7.2. Complete the missing lines
A7.2. Students should do exercises to improve their visualization capabilities. Some
incomplete drawings with missing lines are given and the students are expected to complete
the missing lines. AutoCAD is a flexible tool in such exercises like the one given in FIGURE
28 (1).
FIGURE 28. Missing line exercise.
R7.3. Draw the missing view
A7.3. Multi-view drawings with a missing view are given to the students and they are
expected to draw the missing view like the one shown in FIGURE 29 (1).
FIGURE 29. Missing view exercise.
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R7.4. Create auxiliary views
A7.4. An auxiliary view from a solid model can be easily created by looking at the inclined or
oblique face of model at right angle. When the multi-views are used; primary, secondary,
tertiary auxiliary view can be drawn by aligning coordinate axes parallel and perpendicular to
the related edge view, using object snapping, and measuring and locating the distances of the
related features from the fold lines. An example is given in FIGURE 30 (1).
FIGURE 30. Auxiliary views [22].
R7.5. Draw a point view of a line
A7.5. The point view of a line can easily be drawn with solid models by looking at the model
in the direction of the line. In the case of multi-views, the view can be obtained in two steps:
first drawing primary auxiliary view by looking at the line at right angle, then drawing
secondary auxiliary view through looking at the line of primary auxiliary view in the direction
of the line (1).
R7.6. Measure a dihedral angle
A7.6. Keeping the line of sight parallel to the edges of the angular surfaces, and then drawing
the primary auxiliary view gives the true angle auxiliary view. In solid model, it can be
measured directly by drawing two intersecting lines that are perpendicular to the edges of the
inclined faces and measuring the angle between these two intersecting lines (1).
R7.7. Draw true size of an oblique surface
A7.7. It can be drawn through constructing successive auxiliary views in the way shown in
FIGURE 31 (2).
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FIGURE 31. True size of an oblique surface.
3.1.8. Pictorial Projection/Isometric Drawing
R8.1. Create isometric drawing of an object
A8.1. Isometric drawing can be created in two ways: automatic creation from a solid model or
drawing it in 2-D using isometric axes and grid system. Regular and reversed axis isometric
are easy to draw, however long axis isometric requires rotation of isometric axis. Using the
proper isometric plane and ‘ortho’ mode, isometric drawing is easy to create. Steps of drawing
are shown in FIGURE 32 (1).
FIGURE 32. Isometric drawing in 2-D [23].
R8.2. Draw an isocircle
A8.2. It is easy to draw an isocircle after shifting to the proper isometric plane, and using
isocircle option of ‘ellipse’ command. However, rounding the corners is not possible with
‘fillet’ command, and it requires first drawing an isocircle on the right isoplane and then
trimming unnecessary portions (1).
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R8.3. Create oblique drawing
A8.3. Oblique drawing can’t be created automatically through a solid model, however 2-D
drawing is possible.
R8.3.1. Create oblique drawing in 2-D
A8.3.1. Oblique drawing angles might be 300, 400 or 600. It might be Cavalier, Cabinet or
General type. Drawing an oblique drawing in 2-D is possible (1).
R8.3.2. Create oblique drawing in 3-D
A8.3.2. 2-D oblique drawing through a solid model is not possible (0).
R8.4. Create perspective projection
A8.4. Only a one-point perspective is possible with solid model. All types of perspective
projections, namely one-point, two-point, and three-point perspective projection can be drawn
in 2-D. Horizon line, ground line, vanishing point locations are defined and perspective
drawing is created accordingly as shown in FIGURE 33 (1).
FIGURE 33. Two-Point Perspective Drawing [24].
3.1.9. Section Views
R9.1. Draw cutting plane line
A9.1. Creating cutting plane line is easy with solid model. Line style and arrow location are
arranged in accordance with ISO or ANSI standards like the one given in FIGURE 34. It is
possible also in 2-D (1).
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FIGURE 34. Cutting plane line.
R9.2. Create full section view of an object
A9.2. Section view at the desired cutting plane location, defined labeling and scale is very
easy in solid modeling as shown in FIGURE 35. It is possible also in 2-D but the way through
solid model is more practical (1).
FIGURE 35. Full section view.
R9.3. Draw a half section view
A9.3. It is possible to create a half section view as given in FIGURE 36 through solid
modelling or directly drawing in 2-D (1).
FIGURE 36. Half section view.
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R9.4. Draw an offset section view
A9.4. An offset section view can be created automatically from solid model or be drawn in 2D as given in FIGURE 37 (1).
FIGURE 37. Offset section view.
R9.5. Create a rotated (revolved) section view
A9.5. There is not any command for a rotated section view, but it can be obtained as full
section view and then move it to the required position. It is possible in 2-D as shown in
FIGURE 38.
FIGURE 38. Revolved section view.
R9.5.1. Create a rotated (revolved) section view from solid
A9.5.1. There is no special command. However, it can be obtained as full section view be
moved to the required location (1).
R9.5.2. Create a rotated (revolved) section view in 2-D
A9.5.2. Drawing a revolved section view in 2-D is possible (1).
R9.6. Section ribs, webs, lugs and other thin features
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A9.6. Automatic section lining (cross hatching) from a solid model is not possible. However,
they can be arranged in 2-D section views. An example is given in FIGURE 39.
FIGURE 39. Section view of a solid model [25].
R9.6.1. Section ribs, webs, lugs and other thin features from a solid model
A9.6.1. Automatic section lining from a solid model is not possible since rib, web or lug is not
defined as solid. Spoke and web discrimination is not made (0).
R9.6.2. Section ribs, webs, lugs and other thin features in 2-D
A9.6.2. Drawing section view and omitting hatching in 2-D is possible (1).
R9.7. Create an aligned section view
A9.7. Aligned section view is possible both in 3-D and 2-D as shown in FIGURE 40.
FIGURE 40. Aligned section view.
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R9.7.1. Create an aligned section view from a solid model
A9.7.1. AutoCAD provides foreshortened true projection in full section view. However,
rotated conventional aligned section view can be obtained from the solid model by creating
aligned cutting plane lines (1).
R9.7.2. Create an aligned section view in 2-D
A9.7.2. Rotated conventional aligned section view is possible in 2-D (1).
R9.8. Draw a broken-out section view
A9.8. It is possible to draw a broken-out section view in both 2-D and 3-D. An example is
given in FIGURE 41 (1).
FIGURE 41. Broken-out section view [26].
3.1.10. Dimensioning and Tolerancing
R10.1. Dimension and assign tolerances in accordance with the international standards
A10.1. AutoCAD provides the dimensioning and tolerancing tools that are in line with
international standards. Basic standards are given on tolerancing and dimensioning in [27] and
[28], on limits and fits in [29] and [30], on geometrical tolerances in [31], [32] and [33] (1).
R10.2. Use unidirectional or aligned system of placing dimensions
A10.2. Unidirectional is standard for mechanical engineering applications. Both systems of
placing can be used as shown in FIGURE 42 (1).
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FIGURE 42. Unidirectional and aligned dimensioning.
R10.3. Position and place the dimensional information at the proper locations
A10.3. Positioning spacing should be in accordance with the standards as explained in FIGURE
43. AutoCAD is a flexible software leaving the choices to the user. Therefore, there might be
non-conformance with the standards. The user should be aware of the standards (1).
FIGURE 43. Positioning and placing dimensional information
R10.4. Use standard text, arrow, dimension and extension line sizes in dimensioning
A10.4. Text size is flexible while arrow, dimension and extension lines are standardized as
explained in FIGURE 44. It can be standardized using drawing templates with modified styles.
AutoCAD has some templates but they need improvements or modifications which can be
done by the user (1).
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FIGURE 44. Standard sizes for dimensional text and lines [34].
R10.5. Dimension the drawing using datum (baseline), ordinate or linear continued
dimensioning
A10.5. AutoCAD provides alternative dimensioning methods. An example of baseline
dimensioning is given in FIGURE 45 (1).
FIGURE 45. Baseline dimensioning example.
R10.6. Create basic and reference dimensions
A10.6. Basic or reference dimensioning is possible. An example is shown in FIGURE 46 (1).
FIGURE 46. Basic and reference dimensions.
R10.7. Define dimension units
A10.7. SI or US customary units can be used. Angular dimensions can be defined as decimal
degree or degrees, minutes, seconds (1).
R10.8. Dimension linear and aligned features
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A10.8. It is easy with object snapping feature at the desired location (1).
R10.9. Dimension arcs
A10.9. Arcs are dimensioned easily by using object snapping feature. An example is given in
FIGURE 47 (1).
FIGURE 47. Arc dimensioning example.
R10.10. Dimension angular features
A10.10. It requires selecting lines of the angle. It can be placed at the proper location (1).
R10.11. Dimension a circle and repetitive features
A10.11. A circle can easily be dimensioned. Repetitive features can be dimensioned using X
as shown in FIGURE 48 (1).
FIGURE 48. Dimensioning a circle and repetitive features.
R10.12.Show drilling operations on the drawing
A10.12. Counter bore, countersink and spot face features can be defined easily as shown in
FIGURE 49 (1).
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FIGURE 49. Counter bore, countersink and spot face dimensioning.
R10.13. Draw center marks and center lines
A10.13. It is practical to draw center mark or center lines through selecting circular feature
(1).
R10.14. Assign tolerances to a drawing
A10.14. Tolerances can be expressed in several ways such as direct limits or as tolerance
values, geometric tolerances, notes referring to specific conditions, a general tolerance note in
the title block (1).
R10.15. Show surface texture
A10.15. Surface texture information such as average surface roughness height, roughness
width, roughness width cutoff, lay direction, waviness height, waviness width, information on
material removal can be shown in ISO or ANSI format. An example is given in FIGURE 50
(1).
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FIGURE 50. Surface texture
3.1.11. Basics of Assembly Drawing
R11.1. Create an assembly drawing in 2-D
A11.1. Assembled assembly drawing is easy to create using the general drawing tools.
AutoCAD has a 2-D library of standard parts, and they can be used in assembly drawing.
Exploded assembly drawing, especially isometric drawing of standard parts takes much time
than the assembled. Examples of the assembly drawing are given in FIGURE 51 (1).
FIGURE 51. Assembly drawing: assembled and exploded.
R11.2. Create an assembly drawing in 3-D
A11.2. Although AutoCAD is a software created mainly for 2-D drawings, its capabilities has
been extending into 3-D drawings. Creating assembly drawings in 3-D is possible, but takes
much time in comparison to solid modelling software (1).
R11.3. Construct an assembly by using the parts’ available solid models
A11.3. Starting with a base component and adding other components using geometric
relations is the way used. Mating and aligning are the most common methods for relating parts
to each other in the assembly, however mating is handled indirectly (1).
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R11.4. Create a parts list in assembled and exploded assembly drawings
A11.4. Parts list or bill of materials can be created. However, different numbers are assigned
to the same part in assembled and exploded assembly views.
R11.4.1. Create a parts list
A11.4.1. Parts list or bill of materials is easy to create (1).
R11.4.2. Assign the same number for the same part in the parts list
A11.4.2. AutoCAD does not differentiate multiple instances of the same part in creating
assembled and exploded views of the assembly in the same drawing file, and therefore
different numbers are assigned for the same part in assembled and exploded assembly
drawings (0).
R11.5. Create a pictorial assembly drawing
A11.5. It can be created both in 2-D and 3-D (1).
R11.6. Create an outline assembly drawing
A11.6. Outline assembly can be drawn in 2-D and 3-D (1).
R11.7. Create a sectioned assembly drawing
A11.7. It can be created as pictorial or multi-view form. Pictorial form can be achieved easily
through solid modelling, however it takes much time to draw it in 2-D. Sectioning in multiview can be done in 2-D and 3-D. Interior features of an assembly can be shown by using also
a different technique such as transparency (1).
3.1.12. Presentation Techniques of Engineering Drawings/Printing
R12.1. Create a printout of a drawing
A12.1. Printouts can be taken in general from the layout page, but in exceptional cases from
the model space. The layout page can be prepared in different page sizes using the templates
which are in line with international and company standards. Many layout pages can be
prepared from a single model (1).
R12.2. Use rendering techniques to create artistic drawings
A12.2. An introductory information on rendering techniques is given to the students, although
creating artistic images is out of scope of mechanical engineering education. AutoCAD
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provides some tools in rendering, such as light source, shadow, sun status and location,
material, texture and mapping (1).
3.1.13. Results of the Assessment
The overall results of the assessment of AutoCAD Mechanical in meeting the requirements of
CAD I course are summarized in TABLE 6. 96 of 104 educational requirements are fulfilled by
AutoCAD Mechanical. The overall rating of AutoCAD in terms of fulfilment of educational
requirements is 92.3%.
Relatively low rate of meeting the requirements are given in solid modelling fundamentals (13
of 17), obtaining multi-views from 3-D model (2 of 3), pictorial projection (5 of 6) and basics
of assembly drawing (7 of 8).
TABLE 6. Assessment of AutoCAD in terms of meeting CAD I requirements.
Number Content
No of
No of fulfilled
Percent of
requirements
requirements
fulfillments
1
Basics of engineering drawing
3
3
100
2
Coordinate systems
4
4
100
3
Basic geometric elements
7
7
100
4
Drawing simple geometric objects and editing
21
21
100
5
Solid modelling fundamentals
17
13
76.5
6
Projection theory/multi-views from 3-D
3
2
66.7
rd
7
Projection of 3 view from others
7
7
100
8
Pictorial projection
6
5
83.3
9
Section view
11
10
90.9
10
Dimensioning and tolerancing
15
15
100
11
Basics of assembly drawing
8
7
87.5
12
Presentation of engineering drawings/printing
2
2
100
104
96
92.3
Overall
3.2. Assessment of AutoCAD in Terms of Fulfillment of the Requirements of a CAD II
Course
The second Computer Aided Drawing/Design (CAD) course (CAD II) deals mainly with
assembly drawing and descriptive geometry.
Similar to the CAD I assessment, the main subjects of the course CAD II, the requirements,
and assessment of AutoCAD in meeting the requirements are evaluated. Each numbered item
defines a main subject of the course, while R and A stand for the requirements in that area and
assessment of AutoCAD in fulfilling the requirement, respectively.
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3.2.1. Introduction to Solid Modelling
A general assessment in part drawing is made in the CAD I assessment. Additional points are
given below.
R1.1. Create basic surfaces
A1.1. The ‘3dface’ command provides triangular or quadrilateral flat (planar) surfaces from
the points specified. The points can be selected on the display by using the object snap facility
or entering their absolute or relative coordinates (1).
R1.2. Create complex surfaces by using the sweeping tool
A1.2. Swept surfaces can be generated by sweeping generator entities along director entities.
An example application is given in FIGURE 52.
FIGURE 52. Sweep command application.
A more complex surface can be created by sweeping directrix along a curved generatrix, as
shown in FIGURE 53 (1).
FIGURE 53. Sweeping directrix along generatrix [18].
R1.3. Create complex surfaces by using revolve tool
A1.3. Select a line, arc, circle, or 2D or 3D polyline to sweep in a circular path around a
selected axis. ‘revsurf’ command is used. An example is given in FIGURE 54 (1).
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FIGURE 54. Revsurf command application.
R1.4. Create complex surfaces or solids by using loft tool
A1.4. With the ‘loft’ command, a new solid or surface can be created by specifying a series of
cross sections. The cross sections define the profile (shape) of the resulting solid or surface.
Cross sections (generally, curves or lines) can be open (for example, an arc) or closed (for
example, a circle). An example application is shown in Figure FIGURE 55 (1).
FIGURE 55. Loft command application.
R1.5. Constrain profile geometry for 3-D modelling
A1.5. Constraints can be created in 2-D by using geometric and dimensional constraints. The
drawing shown in FIGURE 56 can be drawn in 2-D, but it loses all the constraints after creating
the third dimension. It is not possible with AutoCAD to define constrains in 3-D. This is a
major shortcoming of AutoCAD. Third dimension can be obtained after changing the
parameters in 2-D. Another deficiency is the unavailability of Offset constraint (0).
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FIGURE 56. Geometric and dimensional constraining example.
3.2.2. Construction of Solid Features
R2.1. Create standard solid features
A2.1 The solid feature dialogue box like the one given in FIGURE 57 is not available with
AutoCAD Mechanical (0).
FIGURE 57. Solid features dialogue box example.
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R2.2. Edit part feature tree
A2.2. AutoCAD does not recognize a solid as a part, therefore part feature cannot be changed
using the feature tree, which is similar to the one shown in FIGURE 58. However, a properties
table is available with some changeable features (0).
FIGURE 58. Part feature tree example.
R2.3. Create feature-based solid models
A2.3. Feature-based modeling refers to the construction of geometries as a combination of
form features. Solid model of a part can be obtained from the raw material (workpiece)
through form features as shown in the example application given in FIGURE 59 (1).
FIGURE 59. Feature-based modeling example [35].
R2.4. Create a rationale modelling with algebraic equations
A2.4. An equation driven solid model can be obtained from the multi-views drawn using
parametric algebraic equations as shown in FIGURE 60. Since constraints are deleted after
solid modelling, parameters are changed before creating solid model from the multi-views.
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FIGURE 60. Equation driven solid model example [18].
R2.4.1. Create a rationale modelling with algebraic equations in 2-D
A2.4.1. Equation driven solid model can be obtained in 2-D (1).
R2.4.2. Create a rationale modelling with algebraic equations in 3-D
A2.4.2. Equation driven solid model in 2-D is not possible with AutoCAD Mechanical (0).
3.2.3. Tolerances, Surface Quality Marks
The general assessment on tolerances is made in the CAD I context. The assessment for
assembly drawings is given below.
R3.1. Describe the nominal size, tolerance, limits, and allowance of two mating parts.
A3.1 Values for maximum and minimum allowable sizes expressed as maximum material
condition (MMC) and least material condition (LMC) can easily be assigned. Nominal size,
tolerance, limits, allowance of mating parts can be shown. An example of limit values is
shown in FIGURE 61 (1).
FIGURE 61. Limit tolerancing example.
R3.2. Identify a clearance fit, interference fit, and transition fit
A3.2. Fitting data of mating parts can be assigned, and be shown in the desired format as
shown in FIGURE 62. ISO or ANSI standards can be used in designation. In ISO; clearance,
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transition and interference fits, in ANSI; running and sliding, clearance locational, transition
locational, interference locational, and force and shrink fits can be defined.
FIGURE 62. Options for fit format.
R3.2.1. Show clearance fit on drawing
A3.2.1. Clearance fit in ISO or ANSI format can be identified easily (1).
R3.2.2. Identify transition fit on drawing
A3.2.2. Transition fit can be defined and shown on engineering drawing in ISO or ANSI
format (1).
R3.2.3. Show interference fit on drawing
A3.2.3. Interference fit in ISO or ANSI format can be identified easily (1).
R3.3. Describe the basic hole and basic shaft systems
A3.3. Hole or shaft basis fit, and assigned tolerances with the basic size of minimum hole or
maximum shaft size can be defined using the ISO and ANSI standard values. An example is
given in FIGURE 63.
FIGURE 63. Hole and shaft basis fit examples.
R3.3.1. Describe the mating parts by using the hole system
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A3.3.1. Hole basis fitting can easily be defined (1).
R3.3.2. Describe shaft basis fitting
A3.3.2. AutoCAD has a data base to define ISO or ANSI standard, shaft or hole basis fitting
(1).
R3.4. Dimension mating parts by using limit dimensions, unilateral tolerances, and bilateral
tolerances.
A3.4. There are many options in dimensioning and tolerancing of mating parts. Basic size, fit
type with fundamental deviation and international grade data, limit values and tolerances can
be shown. Limit form or note form can be used as explained in FIGURE 64 (1).
FIGURE 64. Example for limit form or note form of metric tolerancing.
3.2.4. Geometric Dimensioning and Tolerancing (GDT)
R4.1. Use feature control frame to assign GDT symbols
A4.1. Feature control frames with the required GDT symbols can be added as shown in the
example of FIGURE 65 (1).
FIGURE 65. Feature control frame example.
R4.2. Create datum and datum features
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A4.2. Datum and datum features can be created. An example of datum and feature control
frame application is given in FIGURE 66 (1).
FIGURE 66. Datum feature and feature control frame example.
R4.3. Define material quality conditions
A4.3. Material quality values of maximum material condition (MMC, M), least material
condition (LMC, L), and regardless of feature size (RFS, S) can be assigned by using feature
control frame as shown in FIGURE 67 (1).
FIGURE 67. Material quality condition examples.
R4.4. Define complex tolerances
A4.4. Complex tolerancing data can assigned by using feature control frames like the one
given in FIGURE 68 (1).
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FIGURE 68. Complex tolerancing example.
R4.5. Define form controls such as straightness, flatness, circularity, cylindricity
A4.5. Form controls can be defined. An example is given in FIGURE 69 (1).
FIGURE 69. An example of circularity control.
R4.6. Define orientation controls such as parallelism, perpendicularity, and angularity.
A4.6. Orientation controls can be defined. An example is given in FIGURE 70 for
perpendicularity control (1).
FIGURE 70. An example of perpendicularity control.
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R4.7. Define profile controls such as line profile and surface profile.
A4.7. Profile controls can be defined. An example is given in FIGURE 71 for surface profile
control (1).
FIGURE 71. An example of surface profile control.
R4.8. Define location controls such as concentricity, position, and runout.
A4.8. Location controls can be defined. An example is given in FIGURE 72 for circular runout
control (1).
FIGURE 72. An example of circular runout control.
3.2.5. Working Drawing and Assemblies
The general assessment on assembly drawing is made in the CAD I context. An additional
assessment is given below.
R5.1. Create revision registers
A5.1. Revision blocks can be created and changes in assembly drawings and part drawings
can be registered (1).
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3.2.6. Threaded Fasteners
R6.1. Draw threads in 2-D
A6.1. Bolt, stud, and screw drawings can be created in detailed, schematic and simplified
forms in accordance with international standards. They can be drawn using AutoCAD content
library or available drawing tools as shown in FIGURE 73. Thread notes should be added by
the user (1).
FIGURE 73. Thread drawing example with different options.
R6.2. Draw threads in 3-D
A6.2. It is possible but takes much time to draw solid model of standard threads. However,
AutoCAD does not recognize the model as a standard threaded part. Therefore, automatic 2-D
projection from the solid model is not in accordance with international standards (0).
3.2.7. Non-Threaded Fasteners, Springs
R7.1. Draw non-threaded fasteners in 2-D
A7.1. Pin, key, rivet, retaining ring, and washer drawings can be created in accordance with
international standards. They can be drawn using AutoCAD library or available drawing tools
as shown in FIGURE 74. AutoCAD library does not include all types. Designation notes should
be added by the user (1).
FIGURE 74. Rivet examples.
R7.2. Draw non-threaded fasteners in 3-D
A7.2. It is possible to create solid model by using either content library 2-D sketch or solid
modelling techniques (1).
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R7.3. Draw spring
A7.3. Spring drawings can be created in 2-D using library items or directly drawing using the
available 2-D tools. 3-D drawing can be obtained from the manufacturer or be drawn by using
3-D drawing tools. Creating 2-D projection from the 3-D drawing is possible for detail
drawing (1).
3.2.8. Mechanisms
R8.1. Draw a spur, worm, and bevel gear in 2-D
A8.1. Gear drawings can be created using library items or by using the drawing tools.
Labeling in accordance with ANSI or ISO standards is possible. Shafts, keyways, and key
seats can be drawn. While using library item, automatic creating of other views from the
available view is possible. Gear cutting data can be shown.
R8.1.1. Draw a spur gear in 2-D
A8.1.1. Spur gear is easy to draw by using the 2-D content library. Non-standard spur gear can
be drawn using 2-D drawing tools (1).
R8.1.2. Draw a worm gear in 2-D
A8.1.2. It is easy to draw a worm gear by using the 2-D content library. It is also possible to
draw by using 2-D drawing tools (1).
R8.1.3. Draw a bevel gear in 2-D
A8.1.3. Bevel gear can be drawn by using the 2-D content library. An alternative to the
content library is to draw by using 2-D drawing tools (1).
R8.2. Draw a spur, worm, and bevel gear in 3-D
A8.2. Creating solid model from an available content library of 2-D gear drawings is easy. It
is also possible to draw using the 2-D drawing tools, but it takes much time in comparison to
drawing by using 2-D content library (1).
R8.3. Draw two gears in mesh in 2-D
A8.3. It is possible to create two spur or bevel gears in mesh. An example is shown in FIGURE
75 (1).
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FIGURE 75. Example of two spur gears in mesh.
R8.4. Draw a cam profile, follower, and displacement diagram in 2-D.
A8.4. AutoCAD has a wizard to create a cam profile, follower and displacement diagram.
However, the number of options for displacement is limited. An example drawing of cam and
follower is given in FIGURE 76. Creating the drawing using 2-D drawing tools is also possible
(1).
FIGURE 76. Cam profile example
R8.5. Create a standard bearing drawing in 2-D.
A8.5. Standard bearing drawings can be created using AutoCAD content library (1).
3.2.9. Welding
R9.1. Designate welding using standard weld symbols
A9.1. AutoCAD provides ISO and ANSI standard symbols to designate all the data related to
welding such as reference line, leader line and arrow, basic weld symbol (location, depth of
CUJSE 14, No. 1 (2017)
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weld), finish symbol, weld symbol (type of weld), dimensions, supplementary symbols, tail
and specifications (1).
3.2.10. Descriptive Geometry
R10.1. Create an auxiliary view using reverse construction technique
A10.1. It can be created using the geometric data of the true geometry in 2-D or 3-D (1).
R10.2. Find true length of a line
A10.2. It can be obtained by creating required auxiliary views, using snapping and aligning
coordinate axes (1).
R10.3. Create point view of a line
A10.3. It is obtained when it is looked at the object in the line direction. This view is created
by drawing successive auxiliary views (1).
R10.4. Create true shape and size of a plane
A10.4. True shape of a plane can be obtained by creating an auxiliary orthographic view
parallel to the plane. This is obtained with the second auxiliary view (1).
R10.5. Create the geometry to be obtained at the intersection of two bodies
A10.5. It is very easy with 3-D modelling. Boolean operator ‘intersection’ creates the
intersection of two bodies (1).
R10.6. Locate a line or a point on a plane
A10.6. 2D intersection points of the line with edges are defined in one of the principal views.
The intersection points are projected on the other view, and the points are joined with a line.
The intersection points are extended to end points. The points of intersection with vertical
lines are found. To locate a point on a plane, a line is drawn from one of the plane’s corner
points through the point. The line on the other view is located (1).
R10.7. Determine piercing points
A10.7 Piercing points can be determined by locating intersecting points and projecting
intersections, after drawing two principal views of the planes and the lines (1).
R10.8. Determine shortest distance between a line and point
A10.8. Using two principal views of the line and point, the distance between the two points
that are obtained after getting secondary auxiliary view is measured (1).
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R10.9. Determine distance between two lines
A10.9. Using two principal views of the lines, the distance between the point and the line that
are obtained after the secondary auxiliary view is measured. It is very easy in 3-D (1).
3.2.11. Results of the Assessment
The results of the assessment of AutoCAD Mechanical in meeting the requirements of CAD II
course are summarized in TABLE 7. 63 of 73 educational requirements are fulfilled by
AutoCAD Mechanical. The overall rating of AutoCAD in terms of fulfilment of the
educational requirements is 86.3%.
A relatively low rate of meeting the requirements is observed in the construction of solid
features (2 of 5), threaded fasteners (1 of 2), introduction to solid modelling (17 of 22),
working drawings and assemblies (8 of 9).
TABLE 7. Assessment of AutoCAD Mechanical in terms of meeting CAD II requirements.
Number Content
No of
No of fulfilled
Percent of
requirements
requirements
fulfillments
1
Introduction to solid modelling
22
17
77.3
2
Construction of solid features
5
2
40.0
3
Tolerances, surface quality marks
7
7
100
4
8
8
100
5
Geometric dimensioning and
tolerancing
Working drawing and assemblies
9
8
88.9
6
Threaded fasteners
2
1
50.0
7
Non-threaded fasteners, springs
3
3
100
8
Mechanisms
7
7
100
9
Welding
1
1
100
10
Descriptive geometry
9
9
100
73
63
86.3
Overall
4. Conclusions
AutoCAD Mechanical has been assessed in terms of the fulfillment of requirements of
two main technical drawing courses, which are available in the mechanical
engineering curriculum. This assessment is not meant as a benchmarking but checks
whether AutoCAD Mechanical meets the educational requirements.
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95
It is concluded that AutoCAD Mechanical meets most of the requirements (96 of 104)
of the CAD I course, which focusses on part drawing. Relatively weak points of
AutoCAD are in multiview - 3D model associativity and basics of assembly drawing.
That is, AutoCAD Mechanical can be effectively used in the CAD I course education.
AutoCAD Mechanical meets 63 of the 73 requirements of CAD II, which focusses on
assembly drawing. It is relatively weak in construction of solid features, 3-D threaded
fasteners and the introduction to solid modelling. AutoCAD Mechanical is good in
both courses, but is not as good in CAD II as in CAD I.
The overall rating of AutoCAD in terms of the fulfilment of educational requirements is
92.3% and 86.3% for CAD I and CAD II, respectively. The slightly lower percentage of
86.3% for CAD II is due to the fact that parts, fasteners (threaded and non-threaded),
mechanisms, gears, cams, bearings, etc. occupy an important portion of CAD II which
focusses on assembly drawing. Although, creating parts and fasteners of the assembly
is possible with the knowledge of CAD I, assembling the parts or drawing the parts
parametrically, which is very important for assemblies, is not as easy with AutoCAD
as with a solid modeling software. Moreover, some features are not possible with
AutoCAD, as mentioned in Section 3.2.
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