Controlling and Editing Dimension Associativity in AutoCAD

By Bill Fane

When you add dimensions by selecting objects or by using Object Snap modes to pick points on the objects, AutoCAD normally creates 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 release of AutoCAD starting with 2002.

If you have to work on drawings created or last edited in versions older than AutoCAD 2002, you must set the DIMASSOC system variable to 2 before later releases will create associative dimensions.

An easy way to make this change for the current drawing is to open the Options dialog box (click the Application button and choose Options from the bottom of the Application menu), 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. To make existing non-associative dimensions associative, use the DIMREASSOCiate command described in the following list. Search for the term DIMASSOC system variable in the AutoCAD help system for more information.

You aren’t likely to need any of these three commands often, but if you do, look up the command name in the online help system:

  • DIMREASSOCiate: If you have dimensions that aren’t currently associative (probably because they were created in older versions of AutoCAD) or they’re associated with the wrong objects, you can use the DIMREASSOCiate command to associate them with points on the objects of your choice.
  • DimDisAssociate: You can use the DimDisAssociate (DDA) 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. In those cases, the DIMREGEN (no command alias) command fixes things.