Chamfer

The Chamfer tool, found on the Modify toolbar, is a convenient tool for quickly modifying the corner of an object by putting an angled edge on it.  This command could also be used to create an angle between two lines rather than drawing in the angle by hand.

When you first use the command in your drawing, the distances are set to zero, and nothing would happen if you were to go on with the command.  To set the distances, type "d" into the command line and hit enter.  You will now be prompted for the first chamfer distance.  Once it is entered, you will be asked for the second, but note that the default second distance is the same value you entered for your first distance.  AutoCAD assumes you will be wanting to make a 45° angle chamfer.  If you need the distances to be different, enter a different value in for the second distance.

Now select the first and second lines that you wish to create the chamfer on.  The lines do not need to be touching; AutoCAD will automatically extend or trim lines to create the chamfer at the appropriate distances.  In most circumstances, however, you will creating chamfers between lines that already meet at a corner.

If you wish to create a Chamfer on multiple corners of your drawing, type "M" (Multiple) in the command line.  You can now use the Chamfer tool repeatedly until you are finished