reverse engineering and digital prototyping for a whole new net

63rd Annual ASEE/EDGD Mid-Year Conference Proceedings, Berkeley, California – January 4-7, 2009

Reverse Engineering and Digital Prototyping for a Whole New Net Generation Engineering Design Graphics

J.M. Leake, D. M. King, J. W. Markowski

University of Illinois at Urbana-Champaign Urbana, Illinois 61801

ABSTRACT - A first year engineering design graphics

course at the University of Illinois has been modified to

more fully accommodate today’s Generation Net

students. Changes include providing multiple paths for

learning CAD software, the addition of a reverse

engineering design project, and exposure to digital

prototyping tools.

In this paper it is argued that (1) by including a

reverse engineering component, students begin to

develop critical cognitive skills essential to a successful

career in engineering, (2) students should be exposed

to the downstream capabilities of mid-range

parametric solid modeling software packages,

including 3D printing and digital prototyping tools, so

that these tools can be used more effectively in other

courses, and (3) by providing multiple paths for

learning CAD software, different learning styles are

accommodated, lifelong learning is promoted, and

students become active participants in their own

instruction. The results of a student survey are used in

support of these assertions.

I. Introduction

Undergraduate students on today's college

campuses have grown up in an increasingly self-guided

culture. The capacity to quickly gather information and

other media on the Internet allows students to sample

from a wide variety of different learning tools, while

the ability to communicate instantaneously with people

around the globe lets them build active communities

outside the confines of their local geography. As these

students bring their experiences to university

campuses, it is important that the engineering curricula

they encounter are able to integrate the new dynamic

learning styles that have arisen from this culture, while

still giving students a solid foundation that will serve

them well in their careers after graduation.

This paper discusses the attempt to integrate these

principles in a first year engineering design graphics

course at the University of Illinois at Urbana-

Champaign (UIUC). Throughout the 2007-2008

academic year, course instructional staff held regular

meetings to determine how to best meet the particular

needs of these students. Modifications made to this

course include:

1. Forgoing the use of a CAD textbook, and instead

providing an array of methods and tools that allow

students to acquire solid modeling skills in a way

best suited to their particular learning style.

2. Establishing a reverse engineering design project

that engages students, while developing critical

cognitive skills needed to solve the complex

problems that they will encounter in the

engineering profession.

3. Employing digital prototyping tools in order to

demonstrate the downstream capabilities of CAD


software.

The students' reactions to these changes were

assessed through a survey conducted in May, 2008.

Further efforts are underway to involve departmental

faculty and to integrate digital prototyping across the

curriculum. This will allow students to use their CAD

skills in the exploration of such advanced analysis

topics as finite element and kinematic analysis.

II. Generation Net

The world has grown considerably flatter and

smaller in the past few decades, with the result that this

ethnically diverse, socially well-connected generation

is heavily influenced by and naturally accustomed to

the accelerated returns technology brings: the perpetual

internet connectivity conduit arranges everyone and

everything in life not by distance but by interest online.

Lifelong access to this resource is as natural as an extra

appendage to new generations and on the whole has

improved confidence, knowledge independence,

optimism, and their capacity to collaborate at the costly

insistence of immediacy, forfeiture of privacy, and—

most paradoxically—detachment from the real world.

As such, this generation learns differently.

“Today’s child is bewildered when he enters the

19th century environment that still characterizes the

educational establishment where information is scarce

but ordered and structured by fragmented, classified

patterns subjects and schedules” said communications

theorist and patron saint of Wired magazine Marshall

McLuhan not of education today, but from 1967. The

law may lag technology by a decade; education more

so. As the tools previous generations made shape

future ones, so should education reconsider and

accommodate the modern student’s learning style.

Weekly course improvement meetings were held

during the spring 2008 semester to find ways to better

accommodate the traits and learning style preferences

of Generation Net (Chubin, 2008) in a first year

engineering design graphics course. Meeting attendees

included the course instructor (baby boomer), the head

graduate teaching assistant (Gen X), and the head

undergraduate lab assistant (Gen Net). Table 1

summarizes the course problems identified in these

meetings, as well as actions taken to address them.

Table 1. Course problems and their solutions. Specific Course Problem Response To promote… Single instructor; lack of new ideas

Weekly head meetings, monthly “steering committee” meeting open to all course staff

Fresh ideas

Lack of communication between instructor, TAs, LAs, and students

Weekly head meetings, monthly “steering committee” meeting open to all

Improved communications

Boring, non-interactive lectures Guest speakers Breadth TA’s lack necessary skills TA mentoring program Competence Language barriers (non-native English speaking TA’s)

Experienced TA writes tips slides that describe important CAD tools each week

Self-help

CAD skills atrophy; course exists in vacuum until senior design

Retain understanding by infusing CAD across curriculum

Curriculum integration, lifelong learning

Linearity institutionalized by step-by-step tutorials

Abandon step-by-step approach; provide multiple paths

Nonlinearity

CAD book became outdated Assignments point to native help files in CAD software

Self-help, lifelong learning

Outmoded assignments More relevant assignments Breadth No student feedback loop Online forum provided for students to get

help from lab assistants Improved communications

Final design project lacks structure Changed to emphasize reverse engineering Experiential learning


Figure 1 - Parametric modeling training materials.

One of the more important findings is that many

students resent being forced to follow the linear step-

by-step tutorials found in many CAD books. In

response, the students were provided with a variety of

resources (e.g., demonstrations, roadmaps to software

help, help sessions, help from other students, etc.) to

assist them in the mastery of the parametric modeling

software used in the course. Figure 1 shows the

students’ response to a survey question addressing the

usefulness of these resources. This survey will be

discussed more fully later in the paper.

III. Reverse Engineering Design Projects - A Focus

on How Things Work

Due to its open-ended, abstract nature, design is

widely recognized as being difficult to teach. Reverse

engineering design projects overcome this problem by

in effect providing a case study from which students

can begin to learn about design. In addition, by actively

engaging in the hands-on product dissection process,

students learn experientially by doing, rather than being

told what to do. Finally, product dissection projects

focus attention on the functionality of the product, on

the essential question, “How does this thing work?”

In 2007 approval was obtained and funding

provided by the College of Engineering at UIUC to

create a product dissection laboratory in support of a

reverse engineering design project in the first year

graphics course. The product dissection laboratory was

established in the fall 2007 semester, and the reverse

engineering projects began at the same time.

The team design project is worth 20% of the

course grade. Deliverables include CAD models and

drawings, animations demonstrating product

functionality, freehand sketches, a 3D print, a written

report and an oral presentation.

Student teams are expected to obtain a

commercially available product or mechanism for

dissection. Guidelines are provided to assist the

students in selecting their products. These guidelines

are taken from the textbook (Leake, 2008) used for the

course. The book includes a chapter on reverse

engineering, as well as sections on the downstream

applications of solid assembly models, including 3D

printing and digital prototyping.

Approximately $60,000 in funding was provided

by the college towards the development of the lab (see

Figure 2). The list of purchased equipment includes a

3D printer, two 3D scanners, several computers, a

printer, dissection tools, cameras, digital calipers, tables

used for dissection, etc. The lab has also inherited a

plotter as well as a granite surface plate and associated

metrology equipment. Using the Dimension SST 1200

3D printer, student teams produce rapid prototype

models of actual parts, and then demonstrate the

prototype’s accuracy by having them replace actual

parts within the assembly. For those parts with

particularly complex geometry, students have access to

a Microscribe G2X 3D Digitizer and a NextEngine

Desktop 3D Scanner. Students gain direct exposure to

these technologies, with student staff responsible for

the operation of this equipment, as well as for training

the other students.


Figure 2 - Product dissection laboratory.

While both the reverse engineering projects and

the product dissection lab have been popular with the

students (see Figures 10, 11, and 12), there have been

some associated costs. The course instructor’s

responsibilities have expanded to include the lab’s

overall management, and a graduate teaching assistant

is employed on a part-time basis to manage the lab on a

day-to-day basis. In addition, several undergraduate lab

assistants have been hired to staff the lab.

IV. What Engineering Students Don’t Learn, and

How Reverse Engineering Can Help

David Goldberg (2008) identifies a number of

skills essential for success in engineering. These things

engineers need to learn, but often don’t, are derived

from Goldberg’s 18 years of experience coaching

industry-sponsored senior design project teams. Figure

3 is a graphical representation of these essential

thinking skills: label, decompose, question, model,

communicate, measure, and ideate. It is a central

argument of this paper that, by including a reverse

engineering component as part of the first year

experience, students begin to develop the critical

cognitive skills essential to a successful career in

engineering and beyond.

Figure 3 - Essential engineering thinking.

The ability to label refers to the importance of

being familiar with the terminology associated with a

given subject. The contention is that you cannot speak

intelligently about a something unless you know the

jargon. Take for example the subject of sailboat

rigging. In order to thoughtfully discuss and reason

about sailboat rigging, it is important to know what, for

example, a halyard, a fiddle block, or a cam cleat, is.

Figures 4, 5, and 6 all show examples taken from

reverse engineering design projects. In Figure 4, a

product decomposition diagram, components must be

named. Figure 5 shows an exploded view and parts list

where once again, the parts must be named. Patent

searches provide a wealth of information, including

help in part naming (see Figure 6).

Decompose refers to that fundamental engineering

skill, the ability to break a complex problem down into

smaller ones, which can then be solved. The notion of

decomposition is clearly an essential element of

parametric solid modeling — hierarchical tree

structures (a feature tree for parts, a part tree for


Figure 4 - Product decomposition diagram.

Figure 5 - Exploded view and parts list.

Figure 6 - Patent drawings.

assemblies), exploded views (see Figure 5), and

modeling and visualization strategies that depend upon

the student’s ability to decompose a part into

component features come to mind. In addition, reverse

engineering projects also provide the opportunity for

students to gain experience with functional

decomposition, as seen in Figure 7.

Knowing how to ask the right questions, that is, the

ability to question is another critical cognitive skill. In

writing, for example, asking the relevant questions —

who, what, how, when, where — serves to organize the

Figure 7 - Functional decomposition.

work. Professional meetings are always more

productive if time is taken beforehand to identify the

critical questions that need answers. With regard to

product dissection and reverse engineering projects, a

functional decomposition diagram like the one shown

in Figure 7 can only be realized through careful

questioning with regard to the inner working of the

product – how does this thing work?

Model creation is the practice of developing a

simplified version of something complex that can then

be used to analyze and solve problems. While

engineering modeling is normally associated with

mathematical models, clearly CAD models are another

type of model ubiquitous in engineering. Figure 8

shows several images of CAD models created for the

reverse engineering design project. Notice too that

today’s parametric models go far beyond geometric

modeling, also serving as models for analysis,

simulation, prototyping, and testing.

The ability to measure is another important

engineering activity. Of course there are countless

examples illustrating the importance of measurement in

engineering. One of the paper’s authors once worked

on the design of a Hong Kong to Macao passenger

ferry. The payload (i.e., number of passengers) and

time required to complete the passage were tightly


Figure 8 - CAD product models.

constrained. Using a navigational chart to plot the water

depth along the route, it was found that the water was

too shallow for the ferry to make the speed necessary to

complete the passage within the required time1, and the

job had to be cancelled. If this simple measurement

task had not been undertaken, the project could have

continued, with unhappy results. Clearly reverse

engineering design projects provide multiple

opportunities for students to gain experience with

instrumentation, as seen in Figure 9. Similarly,

experience working with parametric modeling software

introduces such relevant measurement topics as sketch

constraints, tolerances, design intent, etc.

The term ideate refers to the ability to generate

ideas about something. Ideation is closely associated

with product development, brainstorming, creativity,

innovation, and design thinking. In the reverse

engineering design project, student teams are asked to

consider how a product might be improved, modified

for expansion into new markets, etc. These are both

ideation exercises.

1 If the water depth is sufficiently shallow, the water disturbed by the propeller will be influenced by the sea floor, thus limiting the vessel’s attainable speed.

Figure 9 - CAD lab measurement instrumentation.

Figure 10 - Teamwork and communication in

design.

Finally, the ability to communicate is undoubtedly

essential to success in engineering. The ability to work

collaboratively on a team, to make presentations, to

write reports; each of these communication activities

are employed by students in the course of the design

project. Other important communication skills include

listening, networking, and negotiating. Good design

communication also involves pushing oneself to ask

questions (of vendors, customers, collaborators, bosses,

etc.), pursuing leads, and resisting the tendency to go it

alone.


Figure 11 - Product design insights.

V. Student survey results

In order to assess student reaction to the changes

made in the course, a survey was conducted at the end

of spring 2008 semester. This survey contained 21

questions, each falling into one of three categories;

preparation, training, and design. The preparation

category was designed to gage the degree to which

students felt prepared to complete modeling

assignments, many of which are new. Questions on

training focused on resources provided to help students

learn Autodesk Inventor, the parametric modeling

software used in the course. Figure 1 features a

training category question, one which summarizes all

of the other questions in this category. The design

category attempts to capture student views with regard

to the reverse engineering design project. See Figures

10, 11, and 12.

VI. Digital Prototyping – Extending CAD Usage

beyond Geometry Creation

If not regularly used, students cannot be expected

to maintain their CAD skills. While taking at most one

graphics course, it is hard for students to see how their

solid modeling skills can serve them in more advanced

courses. If a student does make the connection, they

often find that the instructor for the later course is

unfamiliar with solid modeling, and consequently

Figure 12 - Insights into how products work.

unable to demonstrate the application of these CAD

skills in order to solve new problems. Digital

prototyping though, provides an opportunity to

seamlessly integrate 3D modeling into other

coursework.

While a reverse engineering project can convert the

abstract nature of design into fertile ground for students

to learn valuable problem solving skills, incorporating

digital prototyping into such a project can bridge the

gap between the qualitative nature of design and the

quantitative nature of such engineering science courses

as kinematics and structural mechanics. Bridging this

gap allows students to gain early exposure to these

types of analysis. This capability demonstrates the

versatility of CAD software, thereby facilitating its

integration into other engineering courses while

demonstrating that the uses of parametric solid models

extend well beyond geometry creation.

V1I. Using Digital Prototyping in a Introductory

Level CAD Classroom

Digital prototyping encompasses a set of tools,

conceptual and analytical, used to evaluate the form, fit,

and function of a product. For example, finite element

analysis is used to assess how a part will react to a

specific loading condition. Other digital prototyping


tools allow the user to create specialized parts for their

models, such as mechanical components, electrical

cables, and structural frames. These tools are valuable

in industry, as they allow companies to test their

products on-the-fly and to identify opportunities for

design improvement without producing physical

prototypes. Digital prototyping tools are now prevalent

in mid-range parametric solid modeling software

packages like Autodesk Inventor. These tools include:

• Stress Analysis: Finite-element analysis software

• Design Accelerator: Generators and calculators for

creation of mechanically correct components (e.g.,

gears, shafts, springs)

• Dynamic Simulation: Kinematic analysis software

• Frame Generator: Structural frame assembly

generation featuring automated selection and

placement of standard frame members

• Cable and Harness: A design environment used to

add cable and harness connections between

electrical parts

Adding material to an engineering course is always

problematic. Instructors must balance the need to cover

the fundamentals, while still managing to address

technological breakthroughs. To meet this problem,

much of the training for digital prototyping in this

course is provided outside of class, where students are

expected to take responsibility for learning the material.

Class instruction is limited to a single fifty minute

lecture, including an overview of the digital

prototyping tools, how to launch them, and how to

access training materials provided by Autodesk.

In addition to these training materials, the course

staff holds office hours and provides some written

introductions to the tools. Digital prototyping is taught

after the students have gained reasonable proficiency

using Autodesk Inventor. Consequently learning to use

the digital prototyping modules, while certainly

Figure 13 - Finite element analysis

challenging, is not an overwhelming task. This type of

instruction allows students to identify materials that

best suit their particular learning style. Requiring

students to be self-sufficient also promotes lifelong

learning; students come to see that they are capable of

learning new material with minimal handholding.

As part of their reverse engineering project, student

teams are evaluated on their digital prototyping efforts.

Approximately 5% of the project grade is based on how

well the tools are implemented, and upon a discussion

of this implementation included in the written report

and oral presentation. Further, each team is free to

select the digital prototyping solution felt to be most

suitable to their specific product. An example of the

incorporation of digital prototyping techniques into the

reverse engineering design projects is shown in Figure

13.

VIII. Using Digital Prototyping to Integrate CAD

into an Engineering Curriculum

The Industrial and Enterprise Systems Engineering

(IESE) curriculum at UIUC culminates in a senior

design project, where student teams work on industry

sponsored engineering problems. The students gain

valuable industry experience, and often find that they

must revisit material from earlier in their studies. Many

groups find themselves returning to CAD; some teams


look to generate graphics to help explain their project

during a presentation, while others find that CAD takes

a central role in the project. For example, students may

be required to redesign a mechanical component to

reduce stress concentrations.

Such scenarios provide adequate motivation for

integrating CAD into an undergraduate engineering

curriculum. However, most engineering curricula

already cover an ambitious array of topics, and there is

limited room to increase coverage. Digital prototyping

makes it possible to incorporate CAD into existing

courses by allowing instructors to teach existing topics

(e.g., finite element analysis, kinematics) using a CAD

approach. To make the case for integrating CAD into

these courses, a two-day workshop was held at UIUC

in May, 2008, to demonstrate the digital prototyping

tools available in Autodesk Inventor. Conducted by

Autodesk representatives, the workshop was attended

by several members of the IESE faculty who teach

structural mechanics and kinematic analysis courses in

the department. In November, 2008, an Autodesk

representative will once again visit the UIUC campus,

this time to give digital prototyping demonstrations to

students in the following courses: engineering design

graphics, advanced design analysis, and component

design.

IX. Conclusions

A first year engineering design graphics course has

been modified to better address the particular

characteristics and learning style preferences of today’s

Generation Net. These changes include (1) a move

away from linear step-by-step tutorials, instead

providing an array of tools and methods for learning

CAD software, (2) the addition of a hands-on reverse

engineering design project, as well as a new product

dissection lab in support the project, and (3) providing

exposure to digital prototyping tools so that these tools

may be more effectively used in upper level design

analysis classes. In addition, it is demonstrated that a

reverse engineering design project offers many

opportunities for students to develop critical

engineering thinking skills.

X. References

Chubin, D., Donaldson, K., Olds, B., Fleming, L., (2008). Educating Generation Net—Can U.S. Engineering Woo and Win the Competition for Talent. Journal of Engineering Education, 97(3), 245-257. Goldberg, D., (2008), What Engineers Don’t Learn & Why They Don’t Learn It [Video File]. Retrieved November 11, 2008, from: http://www.youtube.com/watch?v=TmMmUdn5x4c Leake, J., Borgerson, J., (2008) Engineering Design Graphics: Sketching, Modeling, and Visualization, Hoboken, NJ: John Wiley & Sons. McLuhan, M., Fiore, Q., (1967), The Medium is the Massage, Penguin Books.

reverse engineering and digital prototyping for a whole new net

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