Dimension Commands:
For example, the illustration above shows two different dimension styles. The one on the left is the default style known as STANDARD. If you do not create a style of your own or modify the standard style, all dimensions will look like this. The dimension line has arrow heads and the dimension text is positioned above the line and is drawn using the current text style. The dimension on the right has been drawn using a new style. The arrows have been changed to obliques, the vertical alignment of the text has been centered and the current text style has been changed.
There are lots of dimension commands which include facilities for indicating tolerances and alternate units dimensioning. However, this tutorial aims to cover the most common commands for general use and constitutes an introduction to dimensioning with
AutoCAD divides dimensions into four main categories: Linear, Radial, Ordinate and Angular. For the purposes of this tutorial we will only consider some of the commands within the Linear, Radial and Angular categories.
When you create dimensions, AutoCAD automatically creates a new layer called "Defpoints". This is a special layer which cannot be deleted or renamed. AutoCAD uses this layer to store dimension information and you can effectively ignore it. (see Object Properties for more information on layers)
When working with dimensions it is very important that line origins are picked accurately so that the resulting measurement and text are correct. Always use an Osnap to pick dimension line origins. If you have a lot of dimensioning work to do, it will be worth using a running Osnap. Running object snaps are set using the Osnap Settings dialogue box. To display this dialogue box type DDOSNAP at the keyboard or select Tools Object Snap Settings from the Pull-down menu. There is also a keyboard short-cut; you can display the Osnap Settings dialogue box simply by hitting the F3 key.