The Scaling for Height text box lets you scale the height of the tolerance relative to the dimension text height. Using smaller text for the tolerances is common. A value of 1 creates tolerance text that is equal to the dimension text height. A setting of 0.5 creates tolerance text that is half the size of regular dimension text.

Figure 15-32: A Basic dimension.

Use the Vertical Position drop-down list to determine how the tolerances are aligned with the main dimension text. This setting has the greatest effect on Deviation tolerances that display two lines of text for the one dimension text line. You have the following choices:

Top: Aligns the tolerance text with the top of the dimension text.

Middle: Aligns the tolerance text with the middle of the dimension text.

Bottom: Aligns the tolerance text with the bottom of the dimension text.

Note The Vertical position setting also applies to stacked fractions, determining how the fractions are justified with the whole-number dimensions.

Use the Zero Suppression section to suppress leading or trailing zeros, or feet and inches. See the preceding explanation of the Primary Units tab for more information.

If you’ve turned on alternate units, you can separately set the precision and zero suppression for alternate unit tolerances in the Precision text box.

Click OK, and then click Close to return to your drawing. You’re ready to start dimensioning!

Changing Dimension Styles

Just as you often need to edit objects in a drawing, you may need to edit dimension styles. Whether you want to use a different dimension style for a certain object or change the properties of a dimension style, you have the flexibility you need. You can change dimensions in the following ways:

Choose a new dimension style.

Create a variant of a dimension style for a certain type of dimension.

430 Part II Drawing in Two Dimensions

Modify the characteristics of the dimension style in use.

Override the dimension style with different dimension options for one dimension that you want to be an exception.

Chapter 14 covers some dimension editing techniques. This section explains how to make changes related to dimension styles.

Choosing a new current dimension style

To start using another dimension style, click the Dim Style Control drop-down list on the Styles toolbar or the Dimension toolbar, and choose the dimension style that you want to use.

Existing dimensions remain unchanged, but any new dimensions that you add from this point forward will use the new current dimension style.

Creating a variant of a dimension style

Create a variant of a dimension style for a specific type of dimension, such as a leader or angular dimension. You might have an architectural dimension style with ticks (rather than arrows) at the end of the dimension lines, but you might want angular dimensions to have open arrows. Here are the steps to do this:

1.Choose Dimension Style from the Dimension toolbar.

2.Click New.

3.From the Use For drop-down list, choose the type of dimension that you want to use with the new variant.

4.Click Continue.

5.Make the changes that you want, using the techniques described earlier in this chapter.

6.Click OK to return to the Dimension Style Manager. Here you see the variant listed under its base (parent) dimension style.

7.Click Close.

Dimensions of the type that you specified now take on the characteristics of the variant. For example, angular dimensions would have an open arrow.

Modifying a dimension to use a new dimension style

You can change the dimension style used by a dimension. Select the dimension and then choose a new dimension style from the Dim Style Control drop-down list on the Styles or Dimension toolbar.

Another method of changing a dimension’s style is to choose Properties on the Standard toolbar and select one or more dimensions. In the Properties palette, click the Dim style item in the Misc section and choose a new dimension style from the drop-down list.

You can choose Match Properties on the Standard toolbar to match the properties of one dimension to those of another. Follow these steps:

1.Choose Match Properties.

2.At the Select source object: prompt, choose the dimension whose properties you want to copy.

3.At the Select destination object(s) or [Settings]: prompt, choose the dimension or dimensions to which you want to copy the properties. (Use the Settings option if you want to copy only some of the properties.)

4.Press Enter to end the command.

Modifying dimension styles

You can easily change a dimension style. The advantage of changing a dimension style is that all dimensions using that style are automatically updated. To change a style:

1.Choose Dimension Style from the Dimension toolbar.

2.Choose the dimension style that you want to change from the list of styles.

3.Choose Modify.

4.AutoCAD opens the Modify Dimension Style dialog box, which is exactly the same as the New Dimension Style dialog box. Use the settings on all of the tabs and make the changes that you want. Click OK to close these dialog boxes and return to the Dimension Styles Manager.

5.Click Close.

All dimensions automatically change to reflect the changed dimension style.

Tip You can create a new dimension style from an existing dimension on the fly by using the Properties palette. Double-click a dimension to open the Properties palette. Click the arrow next to the type of change that you want to make, and make the change. After you’re done, right-click in the drawing area and choose Dim Style Save as New Style. The New Dimension Style dialog box opens so that you can give the dimension style a name. Click OK.

Overriding a dimension style

Sometimes you want to make an exception to a style for one dimension — for example, when suppressing an extension line in a tight space. It isn’t often worthwhile to create a new dimension style for such a situation. To override a dimension style, simply change the properties of the dimension by using the Properties palette.

You can also create an override to the current dimension style. The override is like a subset of the dimension style. After you create the override, all new dimensions that you create using the dimension style include the override changes. To revert back to the original dimension style, you must delete the override. You also have the option to incorporate the override into the dimension style or save it as a new style.

432 Part II Drawing in Two Dimensions

To create a dimension style override, follow these steps:

1.Choose Dimension Style from the Dimension toolbar.

2.Choose the dimension style for which you want to create an override (if it isn’t already selected).

3.In the Dimension Style Manager, click Override.

4.The Override dialog box opens, which is just like the New (or Modify) Dimension Style dialog box. Make the changes that you want using any of the tabs. Click OK.

5.In the Dimension Style Manager, you see the style override listed beneath the dimension style that you selected. Click Close.

New dimensions that you create using the dimension style that you selected now include the override properties.

To stop using the override, open the Dimension Style Manager, right-click the style override to open the shortcut menu, and do one of the following:

Choose Delete to delete the override.

Choose Save to Current Style to incorporate the override properties into the current dimension style.

Choose Rename to create a new dimension style from the override. You see a selection box around the name. Type a new dimension style name and press Enter. This action removes the override and replaces it with the new dimension style.

Removing the override doesn’t change dimensions that you’ve already created with the override.

Updating dimensions

The Dimension toolbar includes an Update button. This command updates selected dimensions so that they use the current dimension style, including any overrides that you may have just made. Use this command when you realize that you want to include some existing dimensions in the overrides that you’ve made.

Comparing dimension styles

You can compare a dimension style with the current dimension style. To do this, follow these steps:

1.Choose Dimension Style from the Dimension toolbar, and choose Compare. The Compare Dimension Styles dialog box opens, as shown in Figure 15-33.

2.In the Compare and With drop-down boxes, choose the two dimension styles that you want to compare. The resulting list shows the differences by system variable. For more information about system variables used in dimensions, see the sidebar, “Dimension System Variables.”

3.Click Close twice to return to your drawing.

Figure 15-33: The Compare Dimension Styles dialog box enables you to compare the properties of two dimension styles.

Copying dimension styles from other drawings

With proper planning, dimension styles make dimensioning much easier and produce more-uniform results. Although you can save dimension styles in your templates, you may sometimes need to work with someone else’s drawing or an old drawing that doesn’t contain the dimension styles that you need. As explained in Chapters 11 and 13, you can use the DesignCenter to import features from other drawings. To import a dimension style, follow these steps:

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STEPS: Changing Dimension Styles

1.Open ab15-b.dwg from your CD-ROM.

2.Save the file as ab15-05.dwg in your AutoCAD Bible folder. This is a tension arm for a commercial dryer, as shown in Figure 15-33. ORTHO and OSNAP should be on. Set running object snaps for endpoint, intersection, and center. The Dims layer is current. If the Dimension toolbar is not visible, right-click any toolbar and choose Dimension.

3.The current dimension style is CIR. From the Dim Style Control drop-down list on the Dimension toolbar, choose LIN.

4.Choose Linear Dimension from the Dimension toolbar. At the Specify first extension line origin or <select object>: prompt, choose the endpoint at 1 in Figure 15-34. (If necessary, press Tab until you see the endpoint tooltip.) At the

Specify second extension line origin: prompt, choose the intersection at 2. At the Specify dimension line location or [Mtext/Text/Angle/Horizontal/

Vertical/Rotated]: prompt, choose an appropriate location above the bottom-most dimension.

5.Choose Dimension Style from the Dimension toolbar. Choose Override and click the Tolerances tab. Change the Tolerance Method to None. Click the Lines tab. In the Extension Lines section, check the Suppress: Ext Line 1 option to suppress the first extension line. Click OK. In the Dimension Style Manager, click Close.

6.Choose Linear Dimension from the Dimension toolbar. At the Specify first extension line origin or <select object>: prompt, choose the intersection at 2 in Figure 15-34. At the Specify second extension line origin: prompt, choose the intersection at 3. At the Specify dimension line location or [Mtext/Text/ Angle/Horizontal/Vertical/Rotated]: prompt, pick the endpoint object snap at the right side of the previous dimension’s dimension line in order to align the two dimensions.

7.The first dimension (the one you created in Step 4) needs to be updated to remove the tolerance. Choose Dimension Update from the Dimension toolbar. At the Select objects: prompt, choose the first dimension. Right-click to end object selection to update the dimension.

8.To list the overrides, choose Dimension Style from the Dimension toolbar. Choose Compare. In the Compare Dimension Styles dialog box, <style overrides> should be displayed in the Compare drop-down list, and LIN should be displayed in the With drop-down list. You see a list of the overrides, which are the only differences between the two. Click Close.

9.To remove the overrides (no tolerance and the first extension line suppressed), rightclick <style overrides> in the Dimension Style Manager and choose Delete. You get the message, Are you sure you want to delete ‘<style overrides>’? Choose Yes. Click Close to return to the drawing.

10.Choose Linear Dimension from the Dimension toolbar. At the Specify first extension line origin or <select object>: prompt, choose the intersection at 4 in Figure 15-34. At the Specify second extension line origin: prompt, choose the

intersection at 5. At the Specify dimension line location or [Mtext/Text/Angle/ Horizontal/Vertical/Rotated]: prompt, pick an appropriate location to the right of the model.

4

Figure 15-34: The tension arm needs some additional dimensions.

11.To compare the CIR and LIN dimension styles, choose Dimension Style from the Dimension toolbar. Choose Compare. LIN should appear in the Compare drop-down list. Choose CIR from the With drop-down list. The result is a list of the differences. Click Close twice to return to your drawing.

12.Save your drawing. It should look like Figure 15-35.

Figure 15-35: The dimensions have been added.