IMAGINiT Manufacturing Solutions Blog

STL and OBJ files into Inventor

STL and OBJ; no these are not text derivatives for cell phone or instant messaging, although if they were maybe they would be Small Taco Lunch and Overheard Bar Joke. No these are file formats. One is used quite often in Rapid Prototyping and CAM manufacturing and the other is used frequently in Visualization software. So let's hit the definitions first. If you already know then you get to skip two paragraphs, time is money.

Definitions:

STL is a file format native to the stereolithography CAD software created by 3D Systems. This file format is supported by many other software packages; it is widely used for rapid prototyping and computer-aided manufacturing. STL files describe only the surface geometry of a three dimensional object without any representation of color, texture or other common CAD model attributes. An STL file describes a raw unstructured triangulated surface by the unit normal and vertices (ordered by the right-hand rule) of the triangles using a three-dimensional Cartesian coordinate system.

OBJ is a geometry definition file format first developed by Wavefront Technologies for its Advanced Visualizer animation package. The file format is open and has been adopted by other 3D graphics application vendors and can be imported/exported from Cheetah3D, Daz3d's Daz Studios, e-Frontier's Poser, Autodesk's Maya, Softimage|XSI, Blender, MeshLab, ZBrush, Misfit Model 3D, 3D Studio Max, and Rhinoceros 3D, Hexagon, Newtek Lightwave, Art of Illusion, GLC Player, Wings3d etc. For the most part it is a universally accepted format. The OBJ file format is a simple data-format that represents 3D geometry alone - namely, the position of each vertex, the texture coordinate associated with a vertex, the normal at each vertex, and the faces that make each polygon.

Granted, the most common out of these two for Inventor users is the STL. Normally the file type is exported through Inventor's Save Copy As function so that rapid prototypes can be created for parts and assemblies. The import process is the rarer occasion as normally this does not have to be worked on after the fact by an Inventor user. There are some occasions that I have been asked for this namely for reference objects or sketch references for recreation of geometry. This would go the same for OBJ file format.

I posted an add-in by a man who is very much more programming intelligent than me a while back involving sheet metal extents. Well Brian was at it again not long ago. He created an add-in for Inventor that would read in STL and OBJ data rather well.

This is accomplished by opening a new Part file and selecting the new icon for importing these types of geometry. Users can select which file type and with the Options choose which units are used.

Once the geometry is in it does not have a lot of modification that can be done on it, but it can be used to section to get references for sketches or just reference data for your assemblies.

There are other importers out there for this kind of data as well if you are avid google searcher, but I rather like how this one is put together. It fits so nicely in the 2010 Ribbon on the add-ins Tab.

You can find the Zip containing the installers (32 and 64) and the Read me here:

Download Facetenablersetup

Brian Ekins Mod the Machine Posting

Granted this is primarily graphics and not hard features, but it is a start and can be useful in some situations.

Until next time, may your geometries always be created with the right hand rule.

Inventor File Translators

There is no doubt Inventor has been on the front lines of the translation battlefield over the past couple of releases. With more and updated translators added each release it becomes somewhat vexing to remember which release does which version of someone else's data and what version you can export to collaborate with. I took some time and put together a matrix of file types and Inventor releases starting with 2009 and 2010.

Download the PDF here - Inventor File Translations

This chart personally replaced my tap drill and metric conversion charts since Inventor takes care of that for me now. The biggest highlights are the usage of Catia, Pro/E, SolidWorks, NX, and SolidEdge files without the need to have them installed on your machine. You heard me right. Some of these programs require you to have Inventor installed in order to translate Inventor files or other CAD files.

You can also find the legacy translators for 2009 and 2008 on the Autodesk Labs website in either the Graduates section or Manufacturing section if they are still available.

Now, don't get too excited because these will bring the files in but will not include their history tree. It is just the nature of different software companies programming what commands do what differently. Now if you already clicked to the Labs site above you will also find Feature Recognition. This is by far the most developed free tool for recognizing other software's features and making them completely editable in the Inventor environment. Other programs like Elysium can do the job too, but be prepared for a hefty price tag.

Until next time, may your files always translate in the right direction.

Proper Weld Documentation & Design

Inventor has the functionality to create proper weld symbols based on known industry standards. So when I got wind of a client of mine that wasn't using weldments and symbols properly I needed to educate them. First let's take a look at what they were using before I showed them the tools in Inventor

Download WeldSymbolstoAvoid

So what tools does Inventor have to remedy this documentation fiasco? First and foremost is the Weldment environment of Inventor which converts normal assemblies to weld capable designs. This is accessed by starting your assembly as a weldment with a weldment template or using the Convert to Weldment command on the Assemble Tab in the Ribbon (older version users will find this in the Convert menu). In this environment you can do many tasks on your designs but most notably are:

1. Creation of Assembly level Preparations (before the weld)
2. Creation of visible welded material (Fillet, Cosmetic, and Groove)
3. Creation of Assembly level Machinings (after the weld)
4. Weldment material can be uniquely specified
5. Creation of Weldment symbols that translate directly to drawings
6. Weld calculators to aid in design

Now for the issue at hand of proper weld symbol documentation, Inventor has the tools to create weld symbols during the creation of all three weld commands. During the command, each dialog box has a Create Welding Symbol checkbox that allows the user to describe what type of weld is being generated so that it can be easily referenced later on. Too many times will an engineer design a weld and then forget the exact details when they reach the documentation process.

This dialog box becomes a very dynamic tool for the symbol creation depending on what is selected. Usually the first item of business is to select the type of weld

If fillet weld linking is selected when generating a fillet weld, then the information in the dialog automatically maps to the designated areas of the symbol. Since Groove welds are much more dynamic in their creation process, this option is not available for them or Cosmetic welds.

Until next time, may your weld beads fill in the right direction

Inventor Tolerance Modeling

Download: Download Inventor Tolerance Modeling

Excerpt:

The ability to work in a virtual Digital Prototype is certainly an invaluable tool for assembly ideation and visualization. Analysis tools such as Inventor's ability to check for potential interferences and drive assembly locational constraints through a range of sizes and positions can help a designer ensure that valid form, fit and function considerations are honored. This virtual prototyping in turn reduces design cycle times, time to market, and ultimately, cost. I am confident using these techniques made me a better Product Designer.

However, performing this analysis on parts modeled to a nominal size is insufficient and error-prone. Designers will place allowable tolerances on parts based on manufacturing processes, material properties, and cost factors. How, then, do I capture and incorporate these factors into my design verification?

Until next time, may your models always be within tolerances!