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AutoCAD Tutorial

AutoCAD 3D Modeling: Managing Regions

August 13, 2003

Although regions are similar to flat surfaces you can use some of 3D solids commands to modify them. The following tutorial shows you how to use Boolean commands to create a complex region. You will also use the MASSPROP command to extract some useful data from the region.


1. Download r16_managing_regions.dwg.

Note: If you are using AutoCAD 2002 or an earlier release download r15_managing_regions.dwg.

2. Open the drawing in AutoCAD. The drawing consists of some regions [Figure 1].

Figure 1

3. Invoke INTERSECT (Modify menu > Solids Editing > Intersect). This Boolean operation creates a region based on the common/overlapping area of selected regions. The command erases the original regions.

4. Select the two top segments. A new region is created [Figure 2].

Figure 2

5. Invoke UNION (Modify menu > Solids Editing > Union). The UNION command creates a region by joining selected ones. The original regions will be removed.

6. Select the top region and the big one. The regions will union [Figure 3].

Figure 3

7. Invoke SUBTRACT (Modify menu > Solids Editing > Subtract). Here you will select two groups of regions. The second group will be subtracted from the first one to create a new region. This Boolean command will also delete the original regions.

8. Select the big region as the first group and then press Enter.

9. Select the circular regions as the second group and then press Enter to create the final region.

10. Alter the shade mode to Gouraud shaded [Figure 4].

Figure 4

11. Invoke MASSPROP (Tools menu > Inquiry > Region/Mass Properties).

12. Select the region. Some useful information appears on Text window [Figure 5]. Press Enter to exit the command.

Figure 5

About the Author

Alireza Parsai is the founder of cadpanel.com. He is a mechanical engineer with more than 12 years experience with AutoCAD. Alireza is an Autodesk Authorized Author, the AutoCAD consultant for Al Khawarizmi Institute, a contributing editor for Augiworld magazine, a writer for CAD Digest, an instructor for AUGI Training Program, and an elected speaker for Autodesk University 2002. He has written 7 books in Farsi, 3 booklets in English, and more than 30 articles for different magazines and newsletters. You can reach him at alireza.parsai@cadpanel.com or visit his website www.cadpanel.com

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