"Engineering Dissection 101": A five week multimedia
module where students, by taking apart and reassembling a simple
mechanical assembly (e.g., a valve, a coupling, etc.), learn the
importance of providing, at the design stage, for accessibility
in view of inspection, maintenance, repair or replacement; for choice
of material for durability, robustness or recycling; for choice
of manufacturing process (casting, forging, machining, welding,
etc.) dictated by use and economy; for choice of form dictated by
function, esthetics and economy, etc.; where they develop the ability
to observe and describe graphically, verbally and in writing (e.g.
by writing a manual for disassembling or reassembling their piece
Students in this course would already have completed 15 weeks of
CAD drafting instruction and would be familiar with orthographic
projections, drawing conventions, dimensioning and tolerances and
with some concepts of production drawings.
The multimedia module would include written material for instruction
and reference, some videos (for instance on manufacturing processes)
some software (e.g., on economics), etc. It would be "media-intensive"
in the sense that it would consist mostly of self-taught, self-paced
instructional material leaving the instructor readily available
for tutoring, coaching and direct involvement with the student groups.
Typically, students working in groups of two would learn and practice:
Taking a simple mechanism apart and reassembling it.
Building a vocabulary of common engineering terms (valves, pistons,
cylinders, screws, nuts, rivets, guides, bushings, shafts, journal
Taking graphical, notes by sketching: the individual parts (perspective,
and axonometric views, dimensioned freehand orthographic views)
and the assembly, (exploded view and external or sectional orthographic
Taking written notes by writing assembly and disassembly instructions.
(A technique might be to take an audio or video record as they
disassemble and reassemble the unit and to edit this into a coherent
"expletiveless" written record.)
The material that might be included for teaching engineering sketching
would be such as that in Croft et al., Engineering Graphics,
Wiley, 1989, Chapter 3, Chapter 4 (Set 4-15), Chapters 5 and 6,
selected sections from Chapter 9 and from Appendix A on Advanced
The students would be expected to complete:
A set of detailed orthographic dimensioned freehand drawings
suitable for shop manufacturing together with axonometric views.
An assembly drawing of the unit including an exploded view of
A written analysis of the design explaining how each piece would
have been manufactured and assembled and a critique of the design
with suggestions on how it could be improved.
A short video tape (5 to 8 minutes) of an oral presentation explaining
the operation, use and design of the simple mechanism constituting
the case study.
Of course, it is not expected that students will learn all this
in great depth. The purpose is to make them aware, through a simple
case study, that here are some of the important factors a designer
has to keep in mind during the design process and that they will,
therefore, have to learn about in the course of their further studies.
The approach to take is more towards awakening the students to the
multiplicity and diversity of topics necessary to perform design
than presenting them with treatises on any of these topics.
Chronology of Events
As this five week portion of the EID 103, Principles of Design
evolved, it became obvious that a certain degree of flexibility
in presenting the material was required depending on the background
of the students. Most of the students in the class had just completed
EID 101 which includes an extensive amount of mechanical drawing
theory and practice. Emphasis was therefore placed on freehand sketching
and the so-called "Brain-Hand-Image-Eye" process of drawing
as a continual cycle of development and expression.
An important objective of this portion of the course was the intensity
of the "hands-on-" design experience to be learned by
the actual disassembly and re-assembly of fairly complicated electromechanical
devices. Following the "heuristic" teaching method, which
encouraged the student to discover design concepts himself by asking
questions, the class was divided into twelve groups of two or three,
with each group given a 5 1/4 inch computer floppy disk drive to
disassemble. Tools were supplied to each group including precision
screwdriver and hex-key sets as well as other miscellaneous items.
A short lecture on the concepts of a disk drive was given using
the overhead projector and accompanying hand out sheets. Thus students
began actual hands on work at the first meeting of the class.
In the second week, a short lesson was given on the concepts of
rational design exposing the student to the ideas of functional
requirements, design parameters, and external, human and input constraints.
In accordance with the heuristic approach, a list of design questions
to be answered by the student in the course of disassembly and reassembly,
was presented. An industrial size butterfly valve was then disassembled
in front of the class as an example of the heuristic approach to
be applied to the disk drive. Several written articles pertaining
to design were then distributed to the class. The students continued
to disassemble the drives and were asked to then reassembly them
before the end of the class.
As was to be expected only a few students were able to successfully
reassemble the drives. This demonstrated the importance of sketching,
blow up drawings, wiring diagrams and notes in the course of disassembly.
Photographs of the drive in various stages of disassembly were displayed
as a guide for the students to complete their assemblies. Each group
was then challenged to devise their own system or procedure for
a successful disassembly and reassembly of the drive down to the
smallest possible components. This included disassembly of the stepper
motor for the read-write head, the drive motor, and hub bearings,
along with an inventory of the many small screws, nuts, bolts and
sensors. All sketch work and notes were to be done in a log book
for later submission as part of the class grade. Students were also
invited to bring cameras to class and utilize the concepts of oblique,
isometric and orthographic projection with photographs. The class
remarked that they were able to work much faster during their second
attempt illustrating an example of the "learning curve"
on hands on manufacturing.
The class continued documenting free hand sketches and notes in
their log books, and a discussion was held on the various written
articles distributed to the class regarding concepts of design including
the manufacturing process, re-cycling of materials and environmental
consciousness. In preparation for the audio/visual student presentation
of next week, the class was coached for about one hour by an adjunct
professor on how to exploit the VCR for report presentation.
Final report were presented and commented on by the class. Each
group worked together on an audio-visual presentation of design
concepts related to their mechanical disassembly and reassembly
of the floppy disk drive. The presentation was recorded with a VCR.
Individual log books with the disassembly procedure, sketches, answers
to heuristic design questions and in many cases, photographs were
also collected. The remaining time was used for the students to
complete final assembly and turn in the disk drives and tools to
The students commented enthusiastically about the course. For many
of them, it was their first opportunity to use precision tools in
a "hands on" environment involving state of the art engineering