Before you determine the dimensions of a project, your design is in flux and many questions may be unanswered. Once you begin dimensioning, you will begin to see if things fit or work together. Dimensioning can be crucial to how well a design works and how quickly it develops. The dimensions answer questions about code conformance if you are an architect; they answer questions about tolerances, fit, and interference if you are involved in mechanical applications. Once you and your design team have reached a design on a schematic; level, communicating even tentative dimensions to others on the team can accelerate design development. Dimensions represent a point from which you can further develop your ideas.
With AutoCAD, you can easily add tentative or final dimensions to any drawing. AutoCAD gives you an accurate dimension without your having to take measurements. You simply pick the two points to be dimensioned and the dimensio n line location, and AutoCAD does the rest. AutoCAD’s associative dimensioning capability automatically updates dimensions whenever the size or shape of the dimensioned object is changed. These dimensioning features can save you valuable time and reduce the number of dimensional errors in your drawings.
AutoCAD’s dimensioning feature has many settings. Though they give you an enormous amount of flexibility in formatting your dimensions, all these settings can be somewhat intimidating to the new user. This chapter will ease you into dimensioning by first showing you how to create a dimension style.
Understanding the Components of a Dimension
Before you get started with the exercises in this chapter, it will help you to know the names of the different parts of a dimension. Figure 9.1 shows a sample of a dimension with the different parts labeled. The dimension line is the line that represents the distance being dimensioned. It is the line with the arrows on either end. The extension lines are the lines that originate from the object being dimensioned, They show you the exact location from which the dimension is taken. The dimension text is the actual dimension value, usually shown inside or above the dimension line.
Other components of a dimension line include the dimension line extension. This is the part of the dimension line that extends beyond the extension line. Dimension line extensions are usually only used on architectural dimensions. The extension lines “usually extend beyond the dimension lines in all types of dimensions. The extension line offset from origin is the distance from the beginning of the extension line to the object being dimensioned.