CAD and The Lost Art of Draughtsmanship
It should be a given that we can all agree that the point of technical drawing is to convey lots of information
about very complex systems. We do this to allow skilled mechanics and tradespersons to construct artifacts that work, to the
extent possible, as intended by their designers.
I threw in the parenthetical “to the extent possible” in the last sentence because I realized
as I was writing that the artifacts of modern civilization are so complex that, despite everyone’s best efforts, things
sometimes go wrong. In fact, books have been written about the various permutations of a law attributed to have been
formulated by one known to the world simply as "Murphy".
Why have we then deluded ourselves into believing that CAD is the magic bullet to simplify the construction
process? We also seem to have come to believe that the advent of CAD has made it unnecessary to know anything about drafting
(“draughting” in the uppity spelling which headlined this piece).
You don’t believe me? Why then do we still use the locution “CAD Operators?” It
used to make sense when few used CAD, and we wanted to insure fluency in the new paradigm, but nowadays you can’t get
out of school without AutoCAD courses. So, newly hired CAD operators are given a copy of the office’s CAD drafting
standards and all is supposed to be well.
Why then do I still receive drawings that are difficult to read, and why do some offices still send out
drawing packages that look like they came from several different offices?
You still don’t believe me? Click here to open a separate window with a sample drawing shipped with AutoCAD 2002. This is how not to do it, courtesy of Autodesk.
Move the window around so you can look at it while reading this, and then look at the three callouts at
the upper left of the excerpt. Why are the they staggered like stairs instead of being aligned like the text in this document?
Why do the leader arrows from the two lower callouts come from the middle line of callout text, while that from the topmost
callout comes from the first line of callout text? Why does the leader line from the bottom of the three callouts cross
a leader line from a dimension just below and to the right of that text?
Look at the “VENT FROM BELOW” callout near the upper right of the center grid box. Isn’t
it neat the way the leader line from it goes right through a column of text above it, and how that column of text goes right
through the waste line referred to by the middle left callout block?
Note that none of this has anything at all to do with layers, linetypes, or lineweights, things so fondly
addressed by office CAD standards. It has everything to do with knowing how to draw, however
Maybe “CAD Operators” should not be taught by techies who know their way around CAD software
better than they know their way around the graphic presentation standards necessary to facilitate the transfer of the complex
information presented on drawings to people who are actually going to build the things.
As if that isn’t enough, not infrequently, internal CAD standards are developed by MIS types who
wouldn’t know a hard to understand drawing if they tripped over it, because they know even less about drawing than the
CAD Operators they are charged with supervising.
That the drawing excerpt is not totally unreadable (it’s awfully close, though) is only because
it’s not quite as crowded as some drawings I have seen.
Are we nuts, that we let stuff like this go out our front door after we worked so damned hard to get the
engineering right? Murphy’s predilection for screwing things up tells us we need to make sure we don’t add
lousy presentation as a possible means for him to work his evil ways.
While my technical library used to be lousy with books on drafting, only two remain for me to recommend
to those of you who want to cruise Amazon to find out more about what I’ve been saying. They are:
An Introduction to a Creative Profession, Beakley/Leach; McMillan, 1967. See chapter 14 “Technical Sketching-A Universal Language for the Engineer.”
for Engineers, Earle; Addison-Wesley,
Unfortunately both are fixated upon very basic stuff, and the former even makes some of the mistakes I
pointed out regarding extension of leaders from text blocks, but it’s a start.
My parting thought:
You’ve gotta get this stuff right before you can make all the cool stuff in CAD 3D and Building
Information Modeling systems worth anything at all to you and your clients.
OK, I started writing this newlsletter again at the beginning of the year after a 7 year hiatus because
I needed to do some marketing, and while polemics such as this one make me feel better, they don’t do much to impress
potential clients with my brilliance.
Make sure you have sunglasses handy for the next issue.