In most cases, you shouldn’t have to edit dimension text. Assuming that you drew your geometry accurately and picked the dimension points precisely, AutoCAD displays the right measurement. If you change the size of the associated object, AutoCAD updates the dimension and its measurement. However, you occasionally may need to
AutoCAD creates dimension text as a multiline text (mText) object, so dimension text has the same editing options as ordinary text. Unfortunately, the right-click menu for dimension objects doesn’t include a Text Edit option. You can use the Text Override field in the Properties palette, or type ED (the keyboard shortcut for the ddEDit command) to edit dimension text in the Multiline Text Editor window.
The default text is <> (that is, the left and right angled bracket characters), which acts as a placeholder for the true length. In other words, AutoCAD displays the true dimension length as text in the actual dimension (and keeps the text up-to-date if you change the distance between the dimension’s origin points). You can override the true length by typing a specific length or other text string. You can preserve the true length but add a prefix or suffix by typing it before or after the left-and right-angled bracket characters. In other words, if you enter <> Max., and the actual distance is 12.00, AutoCAD displays 12.00 Max. for the dimension text. If you later stretch the object so that the actual distance changes to 14.50, AutoCAD automatically changes the dimension text to read 14.50 Max. Now you can appreciate the importance of drawing and editing geometry precisely!
Avoid the temptation to override the default dimension text by replacing the angled brackets with a numeric value. Doing so eliminates AutoCAD’s capability of keeping dimension measurements current, but even worse, you get no visual cue that the default distance has been overridden (unless you edit the dimension text). If you’re overriding dimension text a lot, it’s probably a sign that the creator of the drawing didn’t pay enough attention to using precision techniques when drawing and editing. I’m not going to point any fingers, but you probably know whom to talk to.
When you add dimensions by selecting objects or picking points on the objects by using object snap modes, AutoCAD normally creates geometrydriven associative dimensions, which are connected to the objects and move with them. This is the case in new drawings that were originally created in any version of AutoCAD starting with 2002. (Autodesk introduced geometry-driven dimensions in AutoCAD 2002. Before that, AutoCAD normally created dimensions whose parts functioned as a single grouped object but that weren’t connected with the dimensioned object.)
In drawings that were created originally in versions older than AutoCAD 2002, you must set the new DIMASSOC system variable to 2 before AutoCAD 2005 will create geometry-driven associative dimensions. An easy way to make this change for the current drawing is to open the Options dialog box (choose Tools>Options), click the User Preferences tab, and turn on the Make New Dimensions Associative setting. Be aware that this setting affects only new dimensions that you draw from now on. Thus, you’ll end up with geometry-driven associative new dimensions and less than fully associative existing dimensions in your old drawing. Look up “DIMASSOC system variable” in the AutoCAD online help system for more information.
You aren’t likely to need any of these three commands very often, but if you do, look up the command name in the online help system.
? DIMREASSOCIATE: If you have dimensions that aren’t currently geometrydriven (probably because they were created in older versions of AutoCAD) or are associated with the wrong objects, you can use the DIMREASSOCIATE command (Dimensions>Reassociate Dimensions) to associate them with points on the objects of your choice.
? DIMDISASSOCIATE: You can use the DIMDISASSOCIATE command to sever the connection between a dimension and its associated object.
? DIMREGEN: In a few special circumstances, AutoCAD doesn’t automatically update geometry-driven associative dimensions (maybe Autodesk should call them “usually geometry-driven but occasionally asleep at the wheel associative dimensions”). In those cases, the DIMREGEN command will fix things.
Pointy-Headed Leaders
No, I’m not talking about your boss (or about you, if you happen to be the boss). I’m talking about arrows that point from your comment to the object or area about which you’re commenting. AutoCAD treats leaders as a special kind of dimension object (no jokes about dimwitted leaders, now). You can draw leaders and text at the same time easily by using the qLEader (Quick Leader) command, as described in the following steps.
qLEader is an improved version of the old LEADER command, which remains in AutoCAD 2005 for compatibility reasons. I recommend that you use qLEader instead of LEADER. Fortunately, the AutoCAD 2005 Dimension menu and toolbar choices run the qLEader command.
qLEader is another one of those annoying AutoCAD commands that prompts you for some information on the command line and some in a dialog box. Pay close attention to the command line prompts throughout this example:
1. Set a layer that’s appropriate for dimensions current.
See Chapter 4 for details.
2. Set a dimension style that’s appropriate for your needs current.
Choose an existing dimension style from the drop-down list on the Styles toolbar, or create a new style by using the procedure in the section, “Creating and managing dimension styles,” earlier in this chapter.
3. Choose Dimension>Leader or click the Quick Leader button on the Dimension toolbar.
The command line prompts you to select the first leader point — that is, the arrowhead point — and gives you the option of changing leader settings first:
Specify first leader point, or [Settings] <Settings>:
If you want to draw curved rather than straight leader lines or choose a different leader arrowhead style, press Enter now to open the Leader Settings dialog box.
4. Pick a point that you want to point to.
If you use an object snap mode, such as Nearest or Midpoint, to pick a point on an object, AutoCAD associates the leader with the object. If you later move the object, AutoCAD updates the leader so that it points to the new location.
The command line prompts you for the next point — AutoCAD draws a shaft from the arrowhead to this point:
Specify next point:
5. Pick a second point.
If you pick a second point that’s too close to the arrowhead point, AutoCAD doesn’t have enough room to draw the arrowhead, and thus omits it.
AutoCAD repeats the next point prompt so that you can draw a multisegment shaft if you want to:
Specify next point:
6. Pick one more point if you want to, or press Enter if you want a leader with a single shaft.
Pressing Enter tells the qLEader command that you’re finished selecting the points that define the leader shaft. By default, the qLEader command lets you pick up to three points (the arrowhead point and two more points). You can change this behavior in the Leader Settings dialog box (refer to Step 3).
The command line prompts you to specify the width for word-wrapping the text that you’ll attach to the leader:
Specify text width <0.0>:
The default text width, 0.0, turns off word-wrapping and displays your text on a single line. You can type a width or point and click with the mouse.
