IN THIS CHAPTER
Placing dimensions in drawings
Choosing a dimensioning method
Creating and modifying your own dimension styles
Adjusting dimension sizes to suit the drawing plot scale
Placing and modifying annotative dimensions, including details at other scales
In drafting, either CAD or manual, dimensions are special text labels with attached lines that, together, clearly indicate the size of things. Although it’s theoretically possible to draw all the pieces of a dimension by using AutoCAD commands such as Line and mText, dimensioning is such a common drafting task that AutoCAD provides special commands to do the job more efficiently. These dimensioning commands group the parts of each dimension into a convenient, easy-to-edit package, much like a block. In fact, AutoCAD actually produces each dimension as something it calls an anonymous block. I discuss blocks in Chapter 17.
Even better, as you edit an object, by stretching a line for example, AutoCAD automatically updates the measurement displayed in the dimension text label to indicate the object’s new size. And perhaps best of all, AutoCAD’s annotative dimensions adjust their text height and arrowhead size automatically to suit the annotation scale on the model tab or the viewport scale in a layout. I explain the general principles of annotative objects in Chapters 13 and 15; in this chapter, I take a close look at annotative dimensions.