February 20, 2016

CAD Drafting Standards

In working with both large and small companies drafting standards have ranged from rigid to "rigid but rarely followed" to non-existent. Do global standards fix a problem or create a new one? Is there a problem to begin with? Read on to get my take.

Printed on paper standard
I am a proponent of what gets printed on paper being standardized. Mainly I'm thinking of symbols. If someone were to create their own symbol for an electrical outlet for example, it's only going to create confusion to those reading the paper drawings.

Internal standard
Standardization inside the DWG files within an organization makes sense if, and it's a big if, everyone follows it. At a large company I used to work for, we spent a year developing a CAD Standards package with layer names, linetypes, colors, symbols and lineweights. Once developed, we had engineers (typically the younger ones) telling the newer CAD guys to change things to suit their whim as far as what the printed product looked like. I vividly remember numerous arguments about this. What's the point of a standard if someone refuses to follow it? It also affected project budgets when we had to get back into drawings to fix things. Also, internal standardization makes drawing setup easier. Putting all your layers and blocks into a generic drawing with the file also setup to your most often used settings saves time. Open the drawing, do a saveas and put the new file in the appropriate location.

Internal standards make no sense once outside of any individual company (like trying to create a global standard). Mainly it has to do with translation or rogue engineer issues. Once a CAD file leaves your control and gets into the hand of another company you have no idea what software they use. A little communication goes a long way. When working on the civil drawings for a large shopping mall there was a separate company that did the architecture. Instead of getting the whole DWG that I had to sort through, all I needed was the building outline, sanitary locations and water taps. So we communicated that to the architect. It didn't matter what CAD software they used or what layer standard they used.

Not to mention enforcement of a layer standard is implausible outside of your own company. Is some global policing organization going to start levying fines for incorrect symbol usage?

I liken the argument of internal standardization to trying to regulate the pencil the old hand drafter was using. Regulating the outcome is one thing, regulating the process is another.

I'm an advocate of simplistic "standards" within my own files because it makes my life easier. I begin any layer that's existing with an X. Proposed gets a P. To be removed or demolished gets a D. An existing wall goes on a layer called X-WALL. Labels for the existing wall (text, dimensions, notes) are X-WALL-TXT. As far as symbols go, I use standard symbols that existed long before computer drafting programs.

Layer Names
This is a big global stupid. Ever seen a drawing with Discipline-Major-Minor-Status layers? I mean, what the hell is that? When you get to a point that there are no two entities in a drawing on the same layer, you've gone way too far. But at least it's better than ISO 13567 which is insane. If you can easily understand an ISO 13567 layer without looking it up, you're much better than I am. I would rather get my drawings done on time, under budget and have the contents easily identifiable and correct than playing a layername game.

At the end of the day, I'm lucky I don't do government work nor do I do work with any entities that adhere to standards to a degree beyond being useful. I'm careful when working with clients to comply to their standards if they have one. If they don't, I make sure to make everything logical enough so when I'm done with the job anyone can open the drawing and easily figure out what's going on.

Follow me on Twitter @bryanhellard

No comments:

Post a Comment