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CHAPTER 11
Dimensioning

Dimensioning is the art of annotating drawings with precise numerical measurements. The process is generally straightforward in the AutoCAD^® program because everything is typically drawn in real-world scale. Dimensions will automatically display the correct measurements as long as the geometric objects to which they refer are drawn to actual size.

In this chapter, you’ll learn the mechanics of dimensioning in modelspace. Dimensioning in paperspace and in viewports is covered in Chapter 13, “Working with Layouts and Annotative Objects.”

In this chapter, you’ll learn to do the following:

Style dimensions
Add dimensions
Edit dimensions

Style Dimensions

The appearance of dimensions (the size of text and arrows, the length of extension lines, and so on) is controlled by dimension styles. Every drawing comes with a Standard dimension style, which of course is the current style because there is only one by default. When you create more than one dimension style, you must choose which one is current. New dimension objects are assigned the current dimension style in much the same way that objects and layers or text and text styles work.

You can customize dimension styles and even create substyles to control the way different types of dimensions appear according to your personal preferences or to adhere to a corporate or industry standard established for dimensions. For example, if you want to use architectural tick marks rather than arrowheads for linear and aligned dimensions, but want to use arrowheads for radius, diameter, and angular dimensions, you can encode these preferences in a dimension style and a series of substyles.

Exercise 11.1: Create Dimension Styles

In the following steps, you will modify the Standard dimension style and create a few substyles for specific types of dimensions in preparation for adding dimension objects in the next section.

Begin by opening the file Ex11.1-start.dwg (see Figure 11.1), which is among the companion files available for download from the book’s web page, www.sybex.com/go/autocad2016essentials.

images

Select the Home tab on the ribbon if it is not already selected. Expand the Annotation panel and click the Dimension Style button (see Figure 11.2).

Figure 11.2 Accessing the Dimension Style Manager on the ribbon
As you can see in the Dimension Style Manager (Figure 11.3), every drawing has Annotative and Standard dimension styles by default. The Standard style is selected by default. Click the Modify button to alter the Standard style.

Figure 11.3 Dimension Style Manager

You will learn about Annotative styles in Chapter 13.

STYLING DIMENSIONS IN MULTIPLE DRAWINGS

Modifying dimension styles in a particular drawing in no way affects the dimensions or styles in other drawings. If you want to use the same dimension styles in future drawings, customize the dimension styles in your drawing template.
Select the Primary Units tab in the Modify Dimension Style: Standard dialog box (Figure 11.4). Set Precision to 0.000 in the Linear Dimensions section. (If you are in a country that uses a comma instead of a period as a decimal separator, select a comma [,] in the Decimal Separator drop-down menu.) Select Trailing in the Zero Suppression section (see Figure 11.4).

Figure 11.4 Configuring dimension style primary units
Select the Symbols And Arrows tab. In the Arrowheads section, choose Open 30 from the First drop-down (see Figure 11.5). The Second drop-down automatically matches the first by default, so it now says Open 30 as well.

Figure 11.5 Changing arrowheads in the Standard dimension style
Select the Lines tab. Double-click the Offset From Origin value to select it, type 0.125, and press Tab (see Figure 11.6). Observe in the preview image how the distance between the object and its extension lines increases. Click OK and Close to save the modifications you’ve made to the Standard style.

Figure 11.6 Increasing the offset from origin distance

UNDERSTANDING DIMENSION STYLES

Changing a dimension style automatically updates all existing dimension objects in the current drawing that have that style assigned.
Type D (for Dimension Style) and press Enter. The Dimension Style Manager reappears. Click the New button to open the Create New Dimension Style dialog box. Verify that Start With is set to Standard. Choose Angular Dimensions from the Use For drop-down (see Figure 11.7). Click Continue.

Figure 11.7 Creating a dimension substyle for angular dimensions
The New Dimension Style: Standard: Angular dialog box appears. Select the Symbols And Arrows tab. Change the First arrowhead drop-down to Closed Filled. The Second arrowhead automatically changes to Closed Filled as well (see Figure 11.8). The preview image reveals how the angular dimension will appear. Click OK.

Figure 11.8 Customizing the arrowheads in the Angular substyle
Click the New button again in the Dimension Style Manager. Select Radius Dimensions in the Use For drop-down and click Continue. Select Closed Filled in the Second arrowhead on the Symbols And Arrows tab. The preview image again reveals what a radial dimension will look like governed by this substyle; click OK.

Linear dimensions can be either horizontal or vertical. Aligned dimensions measure linear distances at angles other than horizontal or vertical.
Select Standard in the styles list in the left pane of the Dimension Style Manager. The preview image now shows the cumulative effect of the style and its substyles: open arrowheads for linear and aligned dimensions and closed filled arrowheads for angular and radial dimensions (see Figure 11.9). Click Close.

Figure 11.9 The preview image shows how different types of dimensions will appear when they are added to the drawing.
Save your work.

Your model should now resemble Ex11.1-end.dwg, which is available among this chapter’s companion files.

Add Dimensions

In technical drawings, dimensions are typically measurements for which the designer may be legally responsible. So although it is essential to know how to add specific dimensions to a drawing, it is also useful to use inquiry commands that measure linear objects (MEASUREGEOM or DIST) or find areas (AREA) without making specific annotations in the drawing. You will explore how to do so in the following section. In addition, you will add a variety of dimension objects that show specific measurements on the drawing. The section ends with a discussion on how to add a multileader, which is text with an arrow pointing to a specific geometric feature in a drawing.

Exercise 11.2: Use Inquiry Commands

Use inquiry commands when you want to find out (but not document) the length, angle, name, and/or area of a specific feature without annotating the drawing with this information. In the following steps, you’ll explore inquiry commands to get these specific types of information from a drawing.

To begin, open the file Ex11.2-start.dwg from this chapter’s companion files.

images

Toggle on Object Snap mode on the status bar if it is not already on. Right-click the Object Snap button and turn on Endpoint and Intersection running object snap modes.
Click the Distance tool in the Utilities panel of the Home tab on the ribbon. Click points A and B shown in Figure 11.10. The distance 5.000 is shown onscreen, and the command prompt reads as follows:
```
Distance = 5.000, Angle in XY Plane = 26.565,
Angle from XY Plane = 0.000 Delta X = 4.472,
Delta Y = 2.236, Delta Z = 0.000
```
Figure 11.10 Measuring the distance between two points

Press Esc to end the MEASUREGEOM command.
Open the Measure menu in the Utilities panel, select the Radius tool, and select the circle. The command prompt reads as follows:
```
Radius = 1.000
Diameter = 2.000
```
Select the Angle option in the dynamic prompt. Select lines A and B shown in Figure 11.11. The command prompt now gives the following value:
```
Angle = 36.87&ring;
```
Figure 11.11 Measuring the angle between two lines

Press Esc to end the MEASUREGEOM command.
Type AREA (for area) and press Enter. The command prompt reads as follows:

The number of decimal places shown in the inquiry commands is controlled by the Precision drop-down in the Drawing Units dialog box (accessed with the UNITS command).
```
AREA Specify first corner point or
[Object Add area Subtract area eXit]
<Object>:
```
Press Enter to accept the default Object option and select the circle. The command prompt gives these values:
```
Area = 3.142, Circumference = 6.283
```
Press Esc, and the MEASUREGEOM command ends.
Save your work.

Your model should now resemble Ex11.2-end.dwg, which is available among this chapter’s companion files.

Exercise 11.3: Add Dimension Objects

In the following steps, you’ll add dimension objects one at a time using a variety of specialized tools to produce dimensions that are linear, aligned, angular, radial, and so on.

To begin, open the file Ex11.3-start.dwg from this chapter’s companion files.

images

Toggle on Object Snap mode on the status bar if it is not already on. Right-click the Object Snap button and turn on Endpoint and Intersection running object snap modes in the shortcut menu that appears if they are not already selected.

Use the DIMLAYER command to specify which layer dimension objects go on. By default they will go on the current layer.
Click the Dimension tool on the Annotation panel. Click points A and B to specify the first and second extension line origin points, as shown in Figure 11.12. Click point C to specify the dimension line location.

Figure 11.12 Creating a dimension by clicking three points

Dimension objects are typically associated with the geometry to which they refer so that when you modify the geometry, the dimensions automatically update with new measurements.
Click the top red line and then click point A shown in Figure 11.13. Press Enter to end the DIM command.

Figure 11.13 Creating a linear dimension by selecting an object and its dimension line location
Type DIMCENTER (for Dimension Center Mark) and press Enter. Select the circle, and a small crosshair symbol appears at the center of the circle.
Type DIM and press Enter. Click points A, B, and C shown in Figure 11.14.

Figure 11.14 Creating another linear dimension
Type C (for the Continue option) and press Enter. Click the last dimension object you created and then click the lower-left corner of the object being dimensioned to add another dimension below the previous one.
Click points A, B, and C shown in Figure 11.15. An aligned dimension appears, parallel to the angled line.

Many of the separate individual dimensioning commands have been aggregated into the single DIM command in AutoCAD 2016.

Figure 11.15 Adding an aligned dimension
Add the four additional aligned dimensions shown in Figure 11.16, measuring 2, 3, 4, and 5 units.

Figure 11.16 Adding additional aligned dimensions
Click the Dimension tool in the Annotation panel, select lines 1 and 2 shown in Figure 11.17, and then click point A to create an angular dimension object. Select lines 1 and 3 and then click point B to create a second angular dimension.

Figure 11.17 Adding angular dimensions
Select the circle and then click a point inside the circle to locate the radius value (see Figure 11.18). Press Enter to end the DIM command.

Figure 11.18 Adding a radius dimension
Save your work.

Your model should now resemble Ex11.3-end.dwg, which is available among this chapter’s companion files.

Exercise 11.4: Add and Style Multileaders

A multileader is text with a line tipped by an arrowhead that leads the eye to specific geometric features. Multileader styles control the appearance of leader objects in much the same way that dimension styles control the appearance of dimensions. In the following steps, you will add a leader object and then configure the multileader style.

To begin, open the file Ex11.4-start.dwg from this chapter’s companion files.

images

Select the Leader tool in the Annotation panel. Click points A and B shown in Figure 11.19, type Area of circle = 3.142, and then press Ctrl+Enter.

You have to use Ctrl in addition to Enter to end the command because Enter by itself advances to the next line.

Figure 11.19 Adding a leader object
Expand the Annotation panel and click the Multileader Style button. Click the Modify button in the Multileader Style Manager dialog box that appears.
On the Leader Format tab of the Modify Multileader Style: Standard dialog box, choose Dot from the Symbol drop-down in the Arrowhead section (see Figure 11.20). Click OK and Close, and the leader object automatically has a dot on its end.

Figure 11.20 Editing a multileader style
Save your work.

Your model should now resemble Ex11.4-end.dwg, which is available among this chapter’s companion files.

Edit Dimensions

Dimensions have grips that allow you to reposition extension lines, the dimension line, and the dimension text independently of one another.

Exercise 11.5: Alter Dimension Objects

In the following steps, you will edit the length and location of extension and dimension lines directly with grips, adjust a dimension style to affect the appearance of dimension objects, and use a few specialized dimension-editing commands.

To begin, open the file Ex11.5-start.dwg from this chapter’s companion files.

images

Toggle on Object Snap mode on the status bar if it is not already on. Right-click the Object Snap button and turn on Endpoint and Intersection running object snap modes.
Click the horizontal linear dimension with a value of 2.236 to select it. Click the lower-left grip to adjust the length of this extension line. Snap the grip to point A in Figure 11.21. Press Esc to deselect.

Figure 11.21 Grip-editing a dimension object
Type DIMEDIT (for Dimension Edit) and press Enter. The command prompt reads as follows:
```
DIMEDIT Enter type of dimension editing
[Home New Rotate Oblique] <Home>:
```
Type N (for New) and press Enter. A text-editing window appears below the last text you entered. Delete the zero by pressing the Delete key.
Type EQ. (for Equal) and then press Ctrl+Enter to end text-entry mode. Select both vertical linear dimensions having values of 2.236 and press Enter. Figure 11.22 shows the result.

Figure 11.22 Editing dimension text content with DIMEDIT

DIMENSION TEXT WRAP

In AutoCAD 2016 you can now wrap text onto multiple lines if there isn’t enough space to accommodate all the words in between the extension lines. When editing dimension text, simply drag the arrow icon on the right of the multiline text ruler left or right to resize the column, and the dimension text automatically wraps to fit.
Type DIMTEDIT (for Dimension Text Edit) and press Enter. Select the aligned dimension with a value of 2 and press Enter. The command prompt reads as follows:
```
DIMTEDIT Specify new location for dimension text or
[Left Right Center Home Angle]:
```
Type L (for Left) and press Enter. The dimension text is now left-justified in relation to the dimension line, so the 2 is more easily read within the space left between the red lines (see Figure 11.23).

Figure 11.23 Changing dimension text justification with DIMTEDIT
Select the ribbon’s Annotate tab and click the Break tool on the Dimensions panel. The command prompt reads as follows:
```
DIMBREAK Select dimension to add/remove break or [Multiple]:
```
Click Multiple on the command line. Select the dimensions with values of 3 and the upper-left dimension with a value of 5 and press Enter. The command prompt reads as follows:
```
Select object to break dimensions or [Auto Remove] <Auto>:
```
Press Enter to accept the default Auto option, and the DIMBREAK command ends. Breaks are made in the selected dimensions where they cross other objects (see Figure 11.24).

Figure 11.24 Using DIMBREAK to clean up overlapping dimension objects
Save your work.

Your model should now resemble Ex11.5-end.dwg, which is available among this chapter’s companion files.

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CHAPTER 11 Dimensioning

Style Dimensions

Exercise 11.1: Create Dimension Styles

Add Dimensions

Exercise 11.2: Use Inquiry Commands

Exercise 11.3: Add Dimension Objects

Exercise 11.4: Add and Style Multileaders

Edit Dimensions

Exercise 11.5: Alter Dimension Objects

AutoCAD 2016® and AutoCAD LT® 2016

CHAPTER 11
Dimensioning