AUGIWorld Magazine - September/October 2008 - (Page 28)

AUTODESK INVENTOR How to Embrace Third-Party Data There is a rich store of 3D CAD freely available on the Internet. There is more information that is shared internally between vendors and customers. But how to access it? Perhaps the most difficult hurdle obstructing the use of this data is dealing with the many file formats in which the data is made available. ACIS (*.sat) files. Like the DWG, ACIS is actually a widely used proprietary format owned by Spatial Corp. Autodesk products read up to version 7 of ACIS. Older ACIS files can be converted to ACIS v7 using the Hoops ACIS Viewer. Search Google using the terms above to find the download page for the free viewer. Proprietary versus neutral Every CAD software company has developed its own proprietary file format as well as supporting one or more neutral formats. Autodesk Inventor® 2009 reads several proprietary formats such as those used by SolidWorks, Pro/Engineer, and UGS NX. IGES format Figure 1: File types To reach a wider audience, data might be supplied in a neutral format such as ACIS, IGES, or STEP. Opening the file When opening a file that was not created in Inventor, be sure to always click on the Options button in the dialog box after selecting the file type and filename. I will start with a DWG file. Although technically an Autodesk proprietary format, DWG is so widely used that it has become the de facto standard for data sharing. When you click on the Options button, you see an option to Figure 2: File open options Import. Notice there is a distinction between Inventor DWG and non-Inventor DWG files. One of the most common formats is 28 IGES files can be surfaces or solids, but they are usually surfaces. In some cases Inventor can automatically stitch the surfaces into solids. Be sure to experiment with all of the different options when opening the file. For large files of unknown quality I turn off Check Parts on Import, Autostitch, and Promote, and Enable Advanced Healing as these options could take a long time (minutes to as much as several hours) to complete. If the file generally looks good, you can go back and open the file with these options turned on. In my experience there are, more often than not, serious problems with the IGES surfaces that prevent stitching to a solid. Repairing the surfaces is often a daunting task that is probably most efficiently learned through face-to-face instruction with an experienced user. If you need help, don’t forget the F1 key, and contact your Value Added Reseller (VAR) for advanced instruction. At the Autodesk University 2008 conference (http://AU.Autodesk.com), I will present a class on repair of neutral file format data. If you make significant use of neutral files and you have been trying to find a way to justify attending AU, approach your supervisor with an explanation of how repair of a few files can recoup the cost of the conference. (I have to ask: If you are not currently making significant use of third-party data, why not?) Editing solids The most common problem is that you will have a set of surfaces as a “Composite” rather than a Base solid. If you create an Inventor drawing (*.idw) of the part you might not have any trouble or even be aware of the difference. But if you create an idw of an assembly containing the imported part(s), the part might not show up in the view. To remedy this problem expand the view node in the browser and find the part node. Right-click on the part and select to Includes surfaces. When you open one of these non-native files in Inventor, the solid (when it is a solid) will show as a Base feature in the browser without the familiar feature history tree. This is commonly referred to as Figure 3: Includes surfaces a “dumb solid.” You can begin editing an imported base solid by right-clicking on the Base node in the browser and selecting Edit Solid. You can also create sketched features and placed features such as Holes, Fillets, and Chamfers added to the Base feature. You might want to experiment with the Delete Face with the Heal option to remove faces of the Base solid; for example, to remove a hole. Feature recognition STEP format More and more third-party data is being supplied in STEP format. In my experience there are usually fewer problems with STEP data than with IGES. But even flawed data can be used if you know a couple of tricks. In many cases a feature tree can be extracted from the base geometry using the free Feature Recognition add-in available at http://labs.autodesk.com. Once the feature tree is extracted, you can edit just like any native Inventor geometry. w w w. A U G I . c o m http://AU.Autodesk.com http://labs.autodesk.com http://www.augi.com

Table of Contents Feed for the Digital Edition of AUGIWorld Magazine - September/October 2008

AUGIWorld Magazine - September/October 2008 Contents The CAD Manager 2008 Salary Survey Save Time with Impression Blocks In the Family Way Structural Stairs Autodesk University 2008 Preview Action Recorder How to Embrace Third-Party Data On the Back Page

AUGIWorld Magazine - September/October 2008

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