CAD-TO-STL

The .STL file format has become the Rapid Prototyping industry's defacto standard data transmission format. This format approximates the surfaces of a solid model with triangles. For a simple model such as the box shown in figure 1, its surfaces can be approximated with twelve triangles, two on each side, as shown in figure 2. The more complex the surface, the more triangles produced as shown in figure 3.

Almost all of today's CAD systems are capable of producing an STL file. For the user the process is often as simple as selecting File, Save As, and STL. Below are steps for producing high quality STL files from a number of today's leading CAD systems.

| 3D Studio Max | ADT | AutoCAD | Revit |
| Rhino | Revit Platform 2009 |

General Steps

• Most CAD packages will have a couple of options that affect the quality of the STL.
  • Changing a "Deviation" type of value would alter the overall output or tessallation.
  • Changing an "Angle Tolerance" type of value would alter smaller details in your file.
• The tighter these parameters the more triangles placed on the surface of the model.
  • Simple geometries will tend to be a couple hundred kilobytes in size.
  • Complex models will range from 1-5 MB in size and still produce good parts.
  • For many models, files larger than 15 MB may be unnecessary and often result in more time to get your quote and models back.
• In all cases, export your STL file as a binary file. This saves on time and file size.

Please note, these are only general guidelines and may not result in the best possible STL file. Please consult your user's guide or the software developers for more information or technical support. Should we determine that your STL file is inadequate for production, we will contact you to discuss your repair options.

3D Studio Max

• First check for errors
• An STL object must define a complete and closed surface. Use STL-Check modifier to test your geometry before export your object to STL.
• Select an object.
• Click <Modify>
• Click <More...>
• Select "STL-Check" under Object-Space Modifiers
• Select <Check>
• If there are no errors, continue to export the STL file by:
• <File> <Export>
• Select "StereoLitho [*.STL]" in <Save as type>
• Select location in <Save in>
• Enter a name in <File name>
• <Save>
• <OK>
• Export To STL dialog:
• Object Name: Enter a name for the object you want to save in STL format
• Binary/ASCII: Choose whether the STL output file will be binary or ASCII (character) data. ASCII STL files are much larger than binary STL files.
• Selected Only: Exports only objects that you selected in the 3D Studio scene.

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ADT

• Select AEC object . Go to 3D SOLID menu & select convert to 3D SOLID  (ENTER)
• After that you will have an option: Erase selected object [Yes/No]  <Yes>: Enter Y
• All the objects are converted into 3D Solid using the same procedure for each AEC objects
• Select a single solid for STL output... (Must be ONE solid to export to STL)
• Command entry: stlout
• Select objects: Use an object selection method and press ENTER when you finish
• Create a binary STL file? [Yes/No] <Yes>: Enter Y

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AutoCAD (Versions: R14-2000i)

• At the command prompt type "FACETRES"
• Set FACETRES between 1 and 10. (1 Being low resolution and 10 high resolution for STL Triangles)
• At the command prompt type "STLOUT"
• Select Objects
• Choose "Y" for Binary
• Choose Filename

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Revit
Revit doesn't allow direct export to STL files. We have to first save in dwg file and open in AutoCAD to create STL files.

• Go to 3D view
• Go to File menu , select Export CAD format
• A dialog box opens
• Select option
• Scroll down the drop down menu (3D view only) & select 3D polymesh
• Select “ AutoCAD 2004 DWG “ in <Save as type>
• Next open the saved file AUTO CAD
• Enter < Explode > on the command menu
• Select the object and press <enter>
• All the objects are converted into 3D solid
• Select a single solid for STL output... (Must be ONE solid to export to STL)
• Enter < stlout>  or <export > on the command menu
• Select objects: Use an object selection method and press < ENTER > when you finish
• Create a binary STL file? [Yes/No] <Yes>: Enter y

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Revit Platform 2009
Now you can go straight from Revit to STL with this new add-on

Download available at: http://labs.autodesk.com/utilities/revit_stl/term_and_condition/

• To Get Started

  1. Download the ZIP package that contains the installer, installation and user instructions, and a feedback form.
  2. Unzip the downloaded ZIP file.
  3. Follow the Read Me file to install the STL Exporter.
  4. The next time you open Revit 2009 you will see a new option called Export STL under the Tools: External Tools menu.

• To Use It

  1. Load a model and select a 3D view that you want to use as the bases for your print.
  2. Using the instructions in the Read Me file set up your 3D view in the one of the Revit 2009 family of products.
  3. Export the model using the command under the Tools: External Tools menu.
  4. Make any required changes to the STL file using an STL viewer.
  5. Print the STL file using a 3D Printer.

Rhino

• File > Save As
• Select File Type > STL
• Enter a name for the STL file
• Save
• Select Binary STL Files

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