How to Convert 3D Models into STL Files
Exporting from Rhino to .stl
- Setting Up Rhino for 3D Printing
- Open Rhino and type ‘Options’ into the Command Line, then hit enter.
- Navigate to Rhino Options > Appearance > Advanced Settings > Shaded.
- Open the pulldown menu next to Backface Settings and select ‘Single Color for All Backfaces’.
- Choose a bright color other than yellow (yellow is Rhino’s selection color and can cause confusion). Green is recommended.
- Identify and Fix Inverted Normals
- Changing Backfaces to green will make all inverted normals appear green, indicating an issue.
- To fix this, explode the object by typing ‘explode’ into the command line or ungroup by typing ‘ungroup’ until you can select individual faces.
- Select the inverted face and type ‘flip’ into the command line. The face should no longer be green.
- Select all faces in the object and type ‘join’ into the command line to create a single object with all normals facing the correct direction.
- Importing and Scaling the Object
- Type ‘Import’ into the dialog box and navigate to your OBJ file, then select open.
- Use ‘Zoom Selected’ to center your model in the Viewports by typing ‘Z’ then ‘S’ and hitting enter.
- If the model appears different from its original design, select the model and type ‘explode’. If everything turns green, select the entire object, type ‘flip’, then ‘join’ again to correct the normals.
- Scaling the Object for Printing
- Create a box with the dimensions of the printer bed (8″ x 10″ x 10″).
- Scale down your model (type ‘scale’ into the Command Line) until it fits inside the box.
- Delete the box once scaling is complete.
- Ensuring the Model is Watertight
- Use the ‘OffsetMesh’ command to ensure the object is watertight. Delete the box, select your model, and type ‘offsetMesh’ into the Command Line.
- Make sure the offset is in the right direction. If the new mesh (white) is inside the object, click ‘Flip/All’ to make the offset go outward.
- Check the box ‘Delete Input Mesh’, use a thickness of .02, and select ‘OK’.
- Exporting to STL
- Select your model and type ‘export’ into the Command Line.
- Select Stereolithography (.stl) as your file type, name your file, and save it.
Exporting from 3DS Max to .stl
- Opening and Importing Models
- Open 3DS Max and navigate to the Max Logo > Import > Import.
- Select the OBJ file exported from Maya and click ‘OK’. The default settings are fine.
- Identifying and Fixing Inverted Normals
- If all geometry appears black, indicating inverted normals, open the Modify panel.
- Select ‘Polygon’, select the entire model, and click ‘Flip’. Deselect your model to ensure all faces show the correct color.
- Scaling the Model for Printing
- Create a box with the dimensions of the printer bed (8″ x 10″ x 10″).
- To scale to a specific factor, calculate the percentage. For example, 1/96 is approximately 1.0416666666667%.
- Use the Scale Tool set to ‘Uniform Scale’ and ‘Use Selection Center’ to adjust the model until it fits inside the box.
- Delete the box once scaling is complete.
- Resetting X-Form and Applying Shell
- Open the Utilities panel (The Hammer Icon), click ‘Reset X-Form’, then ‘Reset Selected’.
- Right-click the object and select Convert to > Editable Poly.
- Apply a small shell thickness (e.g., 1/16”) using the ‘Shell’ modifier.
- Exporting to STL
- Select the object, navigate to the Max Logo > Export > Export.
- In the export dialog, select Stereolithography (.stl) as your file type, name your file, and click ‘OK’.
- Ensure ‘Export Selected Only’ is checked, then click ‘OK’.
Preparing for 3D Printing in ZPrint
- Opening STL in ZPrint
- Open ZPrint and import your .stl file.
- Ensure the unit is set to inches and click ‘Next’.
- Checking Normals
- Go to Edit > Normals > Invert All Normals. If the model turns black with small white dots, it’s ready. Larger white areas indicate issues needing correction.
- Final Checks and Export
- Return to Edit > Normals > Invert All Normals to correct the orientation.
- Go to View > Calculate Part Statistics to review the print dimensions.
- Once confirmed, proceed to print.
Additional Tips and Considerations
- Scale and Units: Ensure correct scaling before exporting. Match Rhino or 3DS Max units with the 3D printer’s units.
- Wall Thickness: Verify wall thickness meets the 3D printer’s minimum requirements.
- Model Orientation: Optimize orientation to reduce support material and improve surface finish.
- File Size and Complexity: Simplify the model to manage file size without compromising quality.
- Manifold Geometry: Ensure models are manifold (watertight) to avoid printing errors.
- Software Updates: Keep software and firmware updated for bug fixes and new features.
- Test Prints: Conduct small test prints to identify potential issues early.
By following these steps and tips, you can ensure successful conversion of 3D models into STL files, leading to high-quality 3D prints.