About the Types of Dimensions

You can create several types of dimensions for a variety of object types in many orientations and alignments.

The basic types of dimensioning are linear, radial, angular, ordinate, and arc length. Use the DIM command to create dimensions automatically according to the object type that you want to dimension.

You can control the appearance of dimensions by setting up dimension styles, or by editing individual dimensions in special cases. Dimension styles allow you to specify your conventions quickly and maintain industry or project dimensioning standards.

Tip: To simplify drawing organization and dimension scaling, you can create dimensions on layouts rather than in model space.

Linear Dimensions

Linear dimensions can be horizontal, vertical, or aligned. You can create an aligned, horizontal, or vertical dimension with the DIM command depending on how you move the cursor when placing the text.

In rotated dimensions, the dimension line is placed at an angle to the extension line origin points. In this example, the angle specified for dimension rotation is equal to the angle of the slot.

Note: You can also create linear dimensions with extension lines that are not perpendicular to their dimension lines. These are called oblique dimensions and they are most commonly used with isometric drafting. In this case, the dimension line angles will be oriented at 30 and 60 degrees depending on the current isoplane.

Radial Dimensions

A radial dimension measures the radius or diameter of arcs and circles with an optional centerline or center mark. Several options are displayed in the illustration.

Note: When part of the dimension is located within the dimensioned arc or circle, the non-associative centerline or center mark is automatically suppressed.

Angular Dimensions

Angular dimensions measure the angle between two selected geometric objects or three points. From left to right, the example shows angular dimensions created using a vertex and two points, an arc, and two lines.

Ordinate Dimensions

Ordinate dimensions measure the perpendicular distances from an origin point called the datum, such as a hole in a part. These dimensions prevent escalating errors by maintaining accurate offsets of the features from the datum.

Important: The datum is established by the current location of the UCS origin.

In this example, the datum (0,0) is indicated as the hole in the lower-left corner of the illustrated panel.

Arc Length Dimensions

Arc length dimensions measure the distance along an arc or polyline arc segment. Typical uses of arc length dimensions include measuring the travel distance around a cam or indicating the length of a cable.

To differentiate them from linear or angular dimensions, arc length dimensions display an arc symbol by default. The arc symbol, also called a hat or cap, is displayed either above the dimension text or preceding the dimension text.

Baseline and Continued Dimensions

Continued dimensions, also called chained dimensions, are multiple dimensions placed end-to-end.

Baseline dimensions are multiple dimensions with offset dimension lines measured from the same location.

Note: Before you can create continued or baseline dimensions, you must first create a linear, angular, or ordinate dimension to act as a base dimension from which to reference the subsequent dimensions.

Current Layer Override

By default, all new objects are created on the current layer. For new dimension objects, you can specify a default layer that's different than the current layer by specifying the layer with the DIMLAYER system variable.

Rotated Views

Leader landings, components of dimensions, and text objects determine their horizontal and vertical directions from the UCS axes at the time when they are created. If a view in a drawing is rotated, you can first use the UCS /View option to set the horizontal and vertical directions relative to the drawing rather than the rotated view.