Computer-aided design and drafting (CADD) has forever changed the way that engineering services are designed and delivered. Along came the personal computer, and the rest was history. Coupled with electronic delivery, CADD singularly increased the pace at which design information is shared in the market place. To meet these needs, educational institutions rightly overhauled their freshman engineering courses to include training in CADD, but to the exclusion of hand sketching.
Given that graphics is the written language of engineering, we believe that structural engineers must understand orthographic projection theory and hand sketching. Incredibly, most university professors teaching freshman engineering courses are amazed that there is still a need for hand sketching in structural engineering practice. In the minds of some, all work in practice is now done with CADD. And, it is not unusual for employers to encounter younger engineers who are not proficient sketchers, yet are quite capable at working in a CADD environment.
While it is true that in many fields of civil engineering CADD is used almost exclusively, in structural engineering there is an ongoing need to sketch ideas and details by hand for the furtherance or construction of a design. This is because hand sketches can be produced in a fraction of the time needed to draw the same information by CADD. Unfortunately, CADD—without an engineering graphics background—can be a cause for future missteps in the world of graphic communication, that is, the world of engineered construction.
Where are we?
Today’s structural engineering offices are run using CADD. This is the reality. The CADD computers are linked to a network, and the netwo r k may be available to offices around the country, or even the world.
However, design ideas are most often worked out with “redlines” on paper, not on the screen.
There are several reasons for this. Most important is the fact that information is not always easily seen on a computer screen. Most computer screens are not the same size and shape as the drawing being produced, and there is still the question of what to do if you need to look at several drawings at one time. With current technology, working on a screen is not the same as reading something on paper. A common experience, even in the related world of word processing, is that drafts are more easily read and corrected on a paper copy than on a screen. In the CADD environment, redlines are marked in the design process, and then corrected in the computer file. Certain corrections and editing do take place on the screen; however, there is still an immense amount of design work that goes on off-screen.
It is far and away faster to initiate details for CADD with hand sketches.
This is particularly true the detail-intensive practice of structural engineering. Even with structural engineering software that dumps design data into a CADD drawing, a great amount of clean-up work and detailing must be completed using engineering judgment and hand-sketched details.
With CADD backgrounds amassed into drawings from all types of analysis programs, and the ease with which details are copied, there is an awful lot of paper out here—maybe even more than before using CADD.
At least in the foreseeable future, with “paperless” offices notwithstanding, there will still be a lot of paper drawings created.
What to do?
In bygone days, engineers were trained in freehand and instrument drafting. Instrument drafting invo l ved the use of equipment such as scales, triangles, T-squares, compasses, ruling pens, and the erasing shield. This method was used to produce final drawing for fabrication and/or construction.
But, the use of these tools has gone the way of the slide rule. Just as hand-held calculators have taken the place of the “slip stick,” CADD has made the drafting board and a case of instruments a thing of the past.
However, the ability to pull out a pen, grab a cocktail napkin, and sketch up a concept that can save a client two weeks off a construction schedule is a skill that remains timeless.
To become more comfortable with freehand drafting there are a few simple rules to follow.
First and foremost, make your drawing to scale! Obviously using a divider and scale is not called for, but an effort to portray an object in a way that shows relative proportions is required. Drawing two rectangles of roughly the same size, one to represent a 1/2-inch thick base plate, and the other a 2-foot thick concrete footing, is not effective sketching.
Using grid paper, if available, will aid in production of scaled sketches. Roughly estimate the size of the final drawing, then select an interval for each grid such as one square equals 1 inch or 1 foot, depending on the size of the object to be drawn.
Second, choose views that most appropriately show the features of interest. There are six principal orthographic views: top, bottom, front, back, left, and right sides. Always be sure to indicate which of these views you are drawing. Many a confusing discussion has resulted from a field engineer sketching a front view (or an elevation) while the general foreman thought this was a top view (or a plan). Often, more than one view is required to express the concept you want. Be sure that multiple views are shown with the proper relationship to each other.
Third, practice using appropriate line work.
In addition to the outline of the object, use hidden line and centerlines where required.
Begin your sketch using light strokes. Vertical lines should be drawn from top to bottom.
Horizontal lines from left to right for righthanded drafters. Keep the heel of your hand on the paper to steady your stroke. To draw inclined lines, it is helpful to rotate the page so that you are using the same motion used for horizontal lines. To draw circles or ellipses, locate the center, then sketch a box divided into four quadrants about this center. Fill in the arcs in each of the quadrants to complete the figure. Finally, darken lines to highlight your figure. Use the heaviest lines for object outlines and lighter weights for hidden lines and centerlines.
How does it help?
Now that you understand the principals behind sketching, how does it affect the bottom line? Figure 1, shown on page 19, is a sketch drawing done for a modification to a high-energy pipe support at a nuclear power plant. The sketch was made on isometric paper using a triangle. This drawing was prepared in a few minutes and faxed to the job site for construction and material requisition review. The engineering team analyzed the sketched modified support using a computer program (see Figure 2), which demonstrated compliance with established allowable stresses. This simple hand sketch allowed engineering, construction, and material purchasing to all begin their various tasks within a 5-minute timef rame, helping the project team to stay on schedule. Figure 3 shows the structure being installed on the job site.
One of today’s big issues during construction is to provide contractors with quick answers to Requests For Information (RFI).
Most often, hand sketches—which are converted easily to a .pdf format—are the way to quickly respond to these requests. An example of an answer to a steel detail RFI is shown in Figure 4. This response clarified a field situation not foreseen in design. All of this information was drawn within 10 minutes. Figure 5 is a photo of the detail being constructed from the sketched response.
Some engineers cannot communicate without sketching, and it may seem odd, but hand sketching is a means to clarify thinking, just like writing. Ideas can be tested, relationships explored, and details developed. Without the ability to hand sketch, a structural engineer may be at a loss to perform critical structural engineering thinking. The ability to think critically saves money and time for consumers of structural engineering services. As a profession, we cannot afford to let this skill die because of a perceived lack of technological sophistication.
Where do we go?
Structural engineers, by the nature of the profession, must interact with field construction work. Often, this means sketching an idea “on the back of an envelope.” Sketching is needed in the design office, but even more so in the heated environment of construction. RFI answers, more often than not, are sketches.
There is just not enough time to prepare CADD sketches of details when responding to a time critical RFI. In the field, how many times have we drawn a sketch on a steel column or a concrete wall to illustrate a point of construction? For some, it is not possible to think or talk without making a sketch, and that is not a bad state to be in. The hand sketch will not go away.
The availability of an old-style professional designer/drafter, the right arm of the structural engineer, is waning. Most have retired. Short of having engineers draft everything that they design, there is now even more of a need for civil and structural engineers to use hand sketches to assist CADD drafters to understand structural details. The limited training and experience of the CADD drafters now available in the marketplace demands this.
Structural engineering is different from architecture in that the drawings are not the end; they are the means to the end.
Architecture is expressed on the drawings, and a good deal of an architect’s training is in making those drawings; now in CADD, and previously in hand-drafting.
Engineering students are not trained, as such, to draft designs. The design is mathematically based and is expressed on drawings.
CADD is a tool to create mathematical models for the purpose of engineering, but CADD is not the whole of engineering. This is why, from a management standpoint, requiring younger engineers to draft everything that they design is not the only answer.
Quick, graphic communication is still needed and was and should be a part of a structural engineer’s background. Engineering educators must continue to teach engineering graphics theory and hand sketching, both at the freshman level and integrated throughout the four-year curriculum in more advanced design courses. This should not be to the exclusion of CADD, but as a partner with CADD. Engineering practitioners need to work with younger engineers to develop their sketching skills and to teach proper graphical drafting practices.
Peter Carrato, Ph.D., S.E., P.E., is a principal civil engineer with the Bechtel Corporation in Frederick, Md., and can be reached at firstname.lastname@example.org. C. Gary Kellogg is vice president of professional services with Delon Hampton & Associates in Washington, D.C., and can be reached at email@example.com. Both served on the American Society of Civil Engineers’ Committee on Curricula and Accreditation for more than 10 years.