Creating Ordinate Dimensions

Ordinate dimensions display the X or Y ordinate of any drawing point based on an origin point, called a datum. AutoCAD uses the origin of the current UCS to calculate each ordinate, or you can set a different origin. X-datum ordinate dimensions measure the distance of a point from the datum along the X axis. Y-datum ordinate dimensions measure the distance along the Y axis. AutoCAD aligns ordinate dimension text with the ordinate leader line.

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To create an ordinate dimension

  1. From the Dimension menu, choose Ordinate.
  2. At the Select Feature prompt, use one of the following methods:

Specify the leader point to complete the dimension. The ordinate dimension changes from X-datum to Y-datum based on the relative distance from the origin.
To specify an X- or Y-datum ordinate explicitly, without regard to the leader position, choose X or Y, and then place the leader.
Enter m to edit the ordinate text using the Multiline Text Editor, or enter t to edit the dimension text on the command line.

Enter a to rotate the angle of the dimension text.

Command line DIMORDINATE

You can change the ordinate dimension datum either by moving the UCS or by using the datum point option of QDIM (see “Dimensioning Multiple Objects”). Changing the datum is useful for specifying ordinate dimensions at specific offsets to another object point, for example, to indicate holes in a part, or to set a series of coordinates from the corner of a building.

The following procedure creates a series of ordinate dimensions for a metal plate. To place the ordinate dimensions, you move the UCS and use object snaps (see “Snapping to Points on Objects”).

To set the datum point

  1. From the Tools menu, choose Move UCS.
  2. At the Specify New Origin Point prompt, enter int to use the Intersection object snap.
  3. Select the lower-left corner of the box. This places the UCS origin at the selected intersection.

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You can now create ordinate dimensions for the circles based on the new origin. Before you begin, turn on Ortho mode (press Ortho on the status bar, or press F8) to help you create straight-line ordinate dimension leaders.

To identify the datum’s X ordinate

  1. From the Dimension menu, choose Ordinate.
  2. At the Select Feature prompt, enter int to use the Intersection object snap.
  3. At the Of prompt, specify the lower-left corner of the plate.
  4. Specify the ordinate leader endpoint, and then press ENTER.

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You can now use ordinate dimensions to show X and Y ordinates of the circle centers relative to the corner of the plate.

To identify the datum’s Y ordinate

  1. From the Dimension menu, choose Ordinate.
  2. At the Specify Feature Location prompt, enter int to use the Intersection object snap, or press SHIFT, right-click, and choose Intersection.
  3. At the Of prompt, specify the lower-left corner of the plate.
  4. Specify the ordinate leader endpoint.

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To create ordinate dimensions

  1. From the Dimension menu, choose Ordinate.
  2. At the Select Feature prompt, enter cen to use the Center object snap.
  3. Select the first circle to snap to its center.
  4. Specify the leader endpoint.
  5. Repeat steps 1 to 4 for the other two circles in the example.

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1 comment so far ↓

#1 Alex on 12.12.11 at 1:22 pm

Do you know how update a set of already drawn ordinate dimensions so that they relate to a new datum?

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