Drawing on Auto Cad

In This Chapter Using CAD in the drawing office Understanding the origins of AutoCAD Getting to know AutoCAD file formats Familiarizing yourself with AutoCAD LT Getting the lowdown on the newest of the new features
elcome to AutoCAD & AutoCAD LT All-in-One Desk Reference For
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Dummies, your one-stop shop for AutoCAD users of every skill level.
If youíve read this far, we assume you know a thing or two about the worldís
most popular computer-aided drafting program ó enough, at least, to know
that computer-aided drafting usually goes by the much friendlier acronym
of CAD. (And if youíre a brand-new user, you might also cast an eye at this
bookís companion volume, AutoCAD 2007 For Dummies.)
The AutoCAD & AutoCAD LT All-in-One Desk Reference For Dummies is
aimed at AutoCAD users in every discipline ó architecture, mechanical
design, mapping and GIS, product design, survey and civil engineering,
diagramming . . . whatever your field, youíll find useful information here.
We cover the entire CAD workflow process, not forgetting that 90 percent
of the time, what you need to produce at the far end of the workflow is a
clear and well laid-out paper drawing.
Using CAD in the Drawing Office
Personal computers revolutionized the drafting trade in the 1980s. Before
that, some drafting was computerized, but the computers were mainframes
or minicomputers (equivalent to the Stanley Steamers and Baker Electrics of
the early days of motoring), well beyond the price range of most small archi-
tectural or engineering firms.
As a result, even as recently as 30 years ago, virtually all drafting was done
by grizzled veterans wearing green eye-shades in smoke-filled back rooms.
And not on computers!In the old days, apprentice drafters (who were called draftsmen ó or even
draughtsmen ó for it was a male profession) started their careers on the
boards as tracers. Hard to believe, but there was a time before mechanical
reproduction when every copy of an engineering drawing had to be traced,
by hand, from an original. If youíre being forced to learn AutoCAD, you may
grumble, but you should be thankful you donít have to go through a proce-
dure like that!
Today, your job is much easier because of AutoCAD. Maybe your boss is
making you use AutoCAD, or you have to pass a course. But there are other
reasons to use it ó some of which may help you pass that course or get
home from the office a little earlier. Here are some CAD advantages: Precision. AutoCAD is capable of precision to 14 significant digits (ask
your math prof or your counselor why one digit should be more signifi-
cant than another). Thatís way more precise than the best manual
drafter could ever be. Appearance. AutoCAD-produced drawings are cleaner, easier to read
when reduced, and more consistent than manually drafted drawings. Reuse. Itís easy to copy and paste parts of drawings into other drawings
for use in new projects. Scalability. You draw things full-size in AutoCAD on an infinitely large
drawing sheet. This not only eliminates the possibility of scaling errors
as you draw, it also lets you print your drawings at any scale. Sharing work. Drawing files can be shared with consultants and con-
tractors who can add their own information without having to redraft
the whole drawing. Distributing work. No more running dozens of prints and having them
couriered to clients ó using AutoCAD you can electronically transmit
drawings via e-mail or upload them to shared Web space. 3D benefits. Youíre not limited to 2D space; AutoCADís drawing space is
three-dimensional so you can create models of your projects and gener-
ate drawings from them.
Understanding AutoCAD Files and Formats
Like every other computer program under the sun, AutoCAD has its own digi-
tal file format. Unlike a Paint program, where the image is created by series of
dots, CAD programs store the locations of objects in a database format. Every
object in a drawing file ó every line, arc, circle, dimension, and so on óis
located in the 2D or 3D drawing space using a Cartesian coordinate system.
For more on coordinate systems in AutoCAD, see Book VI.