I wanted to mention that there are several AutoCAD tips published by Autodesk and many are for the new AutoCAD 2006. There are also tips for AutoCAD 2002, AutoCAD 2004, and AutoCAD 2005.  Some of these tips may have first appeared in the AutoCAD Communication Center tips and tricks for those with that feature enabled.

Some example AutoCAD 2006 tips:

* Adding pull-down menus
* Extracting Block Attributes
* Creating workspaces for an Enterprise CUI file
* Including object properties in table formula
* Using trigonometic calculations in table formulas
* Dynamic Blocks: Independent Base Point
* Create an arc between two existing arcs
* Changing the diameter of a circle in a Dynamic Block
* Using the Network CUI file
* Dynamic Blocks: To display the property value of an object in a block relative to the block reference
* Improve the internal documentation of your drawing
* Use the SHIFT key to extend objects within a trim operation
* Using Dynamic Input
* Isolating layers using layer groups, layer filters (doing what the LAYISO Express Tool does):
* Change custom lookup property in Dynamic blocks
* Dynamic Block Base Location: Start point or Midpoint
* Using Reverse Lookup
* Easily draw at an angle
* Ensuring drawing integrity and ease of construction
* Share your custom scales
* Dynamic Block Attribute Locking
* Finding the area of hatch entities
* Convert and arc into a full circle
* Transparent 3DORBIT
* Counting objects in a drawing
* Dynamic Block Base Point Type: Dependent or Independent
* Performing calculations
* Using "clean screen"
* Save time when using the TRIM and EXTEND commands
* A Handy button macro for creating a viewport in a layout

Tip Links