STL is the standard file type used by most additive manufacturing systems. STL is a triangulated representation of a 3D CAD model. Below you will find instructions on how to convert CAD to STL for many popular platforms.
The triangulation (or poly count) of a surface will cause faceting of the printed 3D model. The parameters used for outputting an STL will affect how much faceting occurs. You cannot build the model smoother than the STL file. If the STL is coarse and faceted then the physical 3D printed model will be coarse and faceted as well.
However, the smoother/ less faceted your surface is, (the higher the poly count or triangulation) the larger your file. 3D printing can only accept a certain file size; therefore it’s important to find a balance between your model, its desired surface, and the 3D printing process of your choice.
When exporting to STL in your CAD package, you may see parameters for chord height, deviation, angle tolerance, poly count, or something similar. These are the parameters that affect the faceting of the STL. We’ve compiled tips on exporting for the best “surface: file” size ratio below.
The following step-by-step instructions for converting CAD files to STL came from each CAD software company’s website or from 3D printing and design user forums; it’s an overall simplified step-by-step process from the greater 3D printing community. If your CAD software is not listed below or if you require additional assistance, please contact your CAD software technical support for information about exporting to an STL.
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Tinkercad is great for 3D printing simple geometrical objects. Its interface was created with 3D printing in mind.
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SketchUp does not offer STL creation directly within the program. Download the extension for .STL here (note: this plugin is open-source and updated frequently).
Tip: SketchUp isn’t inherently built for model production therefore it’s useful to check your SketchUp file for additional feature accuracies once it’s exported from the interface. We recommend uploading your SketchUp file into Meshmixer (a free program from Autodesk) to check your file for faceting and fix any surface flaws.
Note: We don’t recommend Sketchup for use with 3D printing as it does not export well and is best for early design sketches rather than producing physical models.
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Note: The “High” setting will also produce the largest file size. From Low, Medium to High, the hairdryer sample file in Inventor went from about 6.7MB to 17.6MB to 50MB.
Tip: Before finalizing your export, select the Options tab. Within this window, you can select the resolution (faceting) for your model (High, Medium, Low and Custom) and check that your units are correct. The “High” setting will produce a large file size. Autodesk Inventor allows you to save both individual parts and assemblies in STL format, at all design levels. For a quick overview of designing in Inventor, click here.
To check your modifiers have been applied before exporting:
Note: To change the values associated with each of the resolution settings (High/Medium/Low) you need to edit the Windows registry.
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Note: CATIA V5 is capable of creating STL files from CATPart files, but not from assemblies (CATProduct files) or geometrical representations (car files). Therefore, source files, including those saved in a neutral format (i.e. STEP or IGES), must be saved as CATParts. If the source design was saved as an assembly, it is imported to CATIA as a CATProduct. To create an STL file from it, you must first convert it to a multi-bodied part. The procedure described below is one of several methods for doing this.
Saving CATProduct files as CATPart Files for 3D printing:
Tip: Occasionally some of the components may not align correctly in the combined part because of the way the original assembly was designed. To align parts, select Insert Menu > Constraints Feature.
Before saving the file, it is advisable to review the settings that determine model accuracy and file size. To see these parameters:
Tip: Curves’ accuracy ratio: The higher the setting, the smoother the surface will be when dealing with complex geometries, especially if surfaces contain sudden small changes with small radii (like the bumps on a golf ball).
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Note: IronCAD can export in many file formats depending on your geometry.
Tip: When working in assembly mode, you must save each of the component parts as individual STL files. The procedures for doing so are described below.
Saving a model design in STL format:
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Rhinoceros 4
Tip: Check your objects geometry and surface in the Object Properties tab to ensure object uniformity.
Rhinoceros Version 3 and Later
Rhinoceros enables extensive control of STL properties when saving designs as STL files. Because Rhinoceros software is surface-based, the complete model design (even if an assembly) is saved as a single STL part.
Saving a model design in STL format
Important: STL files are suitable for 3D printing if the models they describe are “watertight”, that is, they do not contain holes or gaps. If an error message appears, click Cancel and fix the model design before saving it as an STL file. Steps for fixing mesh in Rhinoceros are detailed below.
Troubleshooting Model Designs
If a model design contains holes or gaps, it is not suitable for 3D printing. Before saving it as an STL file, you must make it “watertight.”
To close holes and gaps in a model design:
Analyze Naked Edges:
Fix Naked Edges
Option 1:
Option 2:
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3D printing in PolyJet:
Retired PTC Creo Formats: Pro/ENGINEER
Exporting your STL file can be done at all levels of design, for both individual parts and assemblies. When dealing with assemblies, you can specify parts of an assembly to either include or exclude from the resulting STL file. Use the procedure below for saving both parts and assemblies as STL files for eventual 3D printing.
To save a Pro/E as an STL file:
Deviation Control
The Deviation Control settings in the Export STL dialog box affect the accuracy of the model and the size of its file.
Angle Control
This setting regulates how much additional tessellation occurs along surfaces with small radii. The smaller the radii, the more triangles are used. The setting can be between 0 and 1. Unless a higher setting is necessary, to achieve smoother surfaces, 0 is recommended.
Once you have reviewed the above the controls and adjusted your settings, click Apply > OK to create the STL file.
Saving a Pro/E Assembly as an STL File
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Tip: Review the controls for exporting STL files in Solid Edge here.
Note: Solid Edge is capable of creating individual STL files from the components of an assembly, but this functionality is not built into the program. It is achieved through the application programming interface (API), using Visual Basic scripts. This solution does not enable a visual preview of the polygon mesh before saving the STL files.
Solid Edge (Older than ST6)
Note: Solid Edge software from Siemens PLM (formerly USG) supports STL output at the core level, enabling you to save both parts and assemblies as STL files. However, when saving an assembly, all of its components are included in a single STL file.
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STL settings: How to change STL settings
Tip: Review file export options before you save your file from SolidWorks here.
To save a model or a model assembly in STL Format:
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NX software from Siemens PLM (formerly USG), supports STL output at the core level, enabling you to save not only entire parts as STL files, but also selected surfaces of a part. This gives you great flexibility when preparing objects for 3D printing. In addition, assembly output enables you to save several components as a single unit while maintaining each component as a separate volume (shell).
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Prior to exporting, ensure your object is uniform by checking that all surfaces/ vertices are connected.
To check your file for uniformity:
Now your file is ready for export.
Tip: Modifiers can be applied during export or prior.
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ZBrush provides designers with incredible feature capabilities, however those features equate to thousands of tiny polygons that aren’t always feasible for 3D printing. To ensure your part is producible and that its details resolve as desired, download the Decimation Master Plugin from ZBrush.
The Decimation Master Plugin will allow you to optimize the polygon mesh of your part for printing by specifying a percentage of the poly mesh to preserve for export. It will preserve detail while reducing poly count. For a quick overview of the plugin, including masking to preserve areas where high poly count is critical for your model, click here.
Once you have optimized your part using the above steps, it is ready to export as an STL file.
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Maya is a free-form design space not specifically tailored to production, therefore it is especially crucial to check the dimensions and producibility of your design (are the wall thicknesses defined? Are all vertices connected?).
Check features for producibility:
Once you’ve checked your part for producibility, open the Rebuild Surface Options and define the surface density of your part. This will determine the resolution of the final 3D print. Check the design guidelines of your preferred technology to ensure the 3D print process can handle your desired resolution. Design guidelines on each 3D printing technology can be found here.
Now you’re ready to export.