How to Add Dimensions to a Drawing in AutoCAD 2014 - dummies

How to Add Dimensions to a Drawing in AutoCAD 2014

By Bill Fane, David Byrnes

At some point, you will need to add dimensions to your AutoCAD drawing. Start off with this exercise to introduce AutoCAD’s dimensioning functionality by creating linear dimensions that show the horizontal or vertical distance between two endpoints:

  1. Start a new drawing, using the acad.dwt template file.

    This step creates a drawing that uses imperial units, even if your default installation uses metric. It saves lazy writers from having to duplicate our instructions for metric users.

  2. Use the Line command to draw a non-orthogonal line.

    A non-orthogonal line is a segment that’s neither horizontal nor vertical. Make the line about 6 units long, at an angle of about 30 degrees upward to the right.

  3. Set a layer that’s appropriate for dimensions as current.

    Okay, you started from a blank template, so it doesn’t have specific layers, but here is a gentle reminder. You normally have dedicated layers for visible edges, hidden edges, text, dimensions, section lines, hatching, and so on.

  4. Start the DimLInear command by clicking the down arrow at the bottom of the Dimension button on the left side of the Annotate tab’s Dimensions panel and click Linear, or type DLI and press Enter.

    AutoCAD prompts you:

    Specify first extension line origin or <select object>:
  5. To specify the origin of the first extension line, snap to the lower-left endpoint of the line by using an ENDpoint object snap.

    If you don’t have ENDpoint as one of your current running object snaps, specify a single endpoint object snap by holding down the Shift key, right-clicking, and choosing ENDpoint from the menu that appears.

    AutoCAD prompts you:

    Specify second extension line origin:

    You must use object snaps when applying dimensions in order to make later editing work properly.

  6. To specify the origin of the second extension line, snap to the other endpoint of the line by using an ENDpoint object snap again.

    AutoCAD draws a horizontal dimension (the length of the displacement in the left-to-right direction) if you move the crosshairs above or below the line. It draws a vertical dimension (the length of the displacement in the up-and-down direction) if you move the crosshairs to the left or right of the line.

    AutoCAD prompts you:

    Specify dimension line location or
  7. Move the mouse to generate the type of dimension you want — horizontal or vertical — and then click wherever you want to place the dimension line.

    AutoCAD draws the dimension.

    When you’re specifying the dimension line location, you usually don’t want to object-snap to existing objects. Rather, you want the dimension line and text to sit in a relatively empty part of the drawing rather than have it bump into existing objects. If necessary, temporarily turn off running object snap (for example, click the OSNAP button on the status bar) to avoid snapping the dimension line to an existing object.

    If you want to be able to align subsequent dimension lines easily, turn on Snap mode and set a suitable snap spacing (more easily done than said!) before you pick the point that determines the location of the dimension line. You can also use the DIMSPACE command to select several existing dimensions and then automatically space them equally.

  8. Repeat Steps 4–7 to create another linear dimension of the opposite orientation (vertical or horizontal).

  9. Click the line to select it.

  10. Click one of the grips at an end of the line and drag it around.

    The dimensions automatically update, live and in real time, to reflect the current values as you move the mouse.

You probably don’t dimension to four decimal places, use a different font for text, use imperial and metric units, or need to show manufacturing tolerances. Not a problem. AutoCAD controls the look of dimensions by means of dimension styles, just as it controls the look of text with text styles and tables with table styles.

In fact, AutoCAD also uses text styles to control the appearance of the text in dimensions. AutoCAD has about 80 variables that can be used to warp dimensions into just about any perversion that your industry or company can imagine.