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Manage and export valid 3D files for 3D printing from Blender

Summary​

  • 1.1. Preparing the Software
  • 1.2. Polygonal Modeling for a 3D Print
  • 1.3. 3D Printing Modifiers: Best Practices
  • 1.4. Case Study: Creating a cat’s head
  • 2.1. Importing into Blender
  • 2.2. Verification Tools
  • 2.3. Export Your File for 3D Printing
  • 3.1. Double Verticies
  • 3.2. Inverted Faces
  • 3.3. Non Manifold Meshes
  • 3.4. Non-Planar Faces
  • 3.5. Isolated Vertices and Faces
  • 3.6. Acute Angles
  • 3.7. Fine Parts

Often when preparing a file for 3D printing, you may use multiple 3D modeling programs. It’s common to create the base of the file in another program and then import it to Blender to add more details than would be necessary for a 3D print.

 

Importing by Default

Blender supports the following filetypes for import:

Files with texture and meshes:

  • .dae (Collada)
  • .obj (wavefront)
  • .fbx (Autodesk FBX)
  • .x3d/Wrl (x3D Extensible 3D )

Files with mesh information:

  • .stl (Stereolythography)
  • .3ds (3d studio)
  • .ply (Stanford)
  • Fichiers 2d Vectoriels
  • .svg (ScalableVector Graphics)

Note: an .svg can be file can be used in the same manner shown in the section dedicated to text and curves.

 

Add Importable Filetypes with Addons

It’s possible to add more importable filetypes (such as .directX, .lwo, or .dxf for example) by using Addons.

To activate these Addons, open user preferences (Ctrl+Alt+U) and choose the Addons tab. Click on Import-Export and choose the Addons you’re looking to activate.

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Importing with Blender

Example using an .stl file:

  • Go to File / Import / .stl
  • Choose the file from your computer
  • The file is now imported into Blender

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Files created in other programs often do not have the correct scale information. In this example, the file needed to be rescaled to 0.1.

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MeshAnalysis

MeshAnalysis is used to display problems with a Mesh. This tool only works in Edit mode and displays the problems a range of Blue (for lower values) or red (for higher values). If there are problems to be fixed, its important to correct all of the colored faces – the faces that do not need to be fixed will not be highlighted and will be shown in grey. You can find this tool in the properties of the 3D View (by clicking ’N’). Be careful with models with high polygon counts as the mesh analysis will take longer to process.

  • Overhang

This display mode shows the overhang according to the axis of the base. In this example, there are no corrections to make. This tool is very useful to define which part of an object will be the base of a ceramic 3D print or with objects that must have a clearly defined base.

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  • Intersections

This mode displays the intersection of faces.

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  • Thickness

This mode can display the parts of your model that are thinner than a predetermined thickness.

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  • Distortion

Displays the irregular Quads or Ngons faces (faces with more than four edges) that will cause a problematic conversion to triangles.

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  • Sharp Edges

Displays the edges which create a side that is too thin (similar to Thickness).

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PrintTool Box Addon

To learn how to activate this Addon head over to the preceding section that explains “Activating Addons”.

This Addon can be accessed by tapping ’T’ on the 3D viewer, this Addon provides a couple extra features that are not included with MeshAnalysis. It has the advantage of directly selecting the areas that pose problems and possesses finer analysis tools. This tool also has the advantage of working in wireframe mode with activated Modifiers. In edit mode, simply enter the desired settings and click “Check all”. The tool will detect any problems and provide a general error report.

Example: for parts of a human character, the PrintTool Box add-on will select the exact parts of the model that need to be fixed.

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  • Volume: calculates the volume of the model
  • Area: calculates the surface area of the model
  • Solid: indicates if the model is non-manifold and if the faces are oriented in the correct direction. It also gives you the ability to automatically select and deselect any problem vertexes.
  • Intersections: indicates any crossing faces
  • Degenerate: displays any faces that have no size and that may present a problem for some programs
  • Distorted: displays any faceless planes
  • Thickness: indicates any places where the thickness is lower than a predetermined value
  • Edge Sharp: shows any edges that are too sharp
  • Overhang: shows the faces for which the angle as compared with the base is less than a predetermined value
  • Check All: checks all of the above parameters
  • Isolated: deletes any vertices without a volume
  • Distorted: deletes any faceless planes
  • Scale to Volume: modifies the scale of an object according to a predetermined volume
  • Scale to Bounds: modifies the scale of the model according to a maximum length
  • Export Path: exports only the selected area. These two buttons allow you to add the mesh to the export and the texture information of the model for multicolor 3D prints.

The use of these tools can detect potential problems for printing on a 3D Mesh. However, following the rules listed in the “basics tips to meet to design a printable model”, will avoid most of these problems.

Export for a monochrome 3D print

The most common format for a printable monochrome 3D model is .stl (Stereolithography).

To export an .stl go to File / Export / .stl

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Select the folder where you’d like the file to be exported and check the boxes of the modifiers you’d like to use. Name the file then export.

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Export for a multicolor 3D print

  • .obj Files

The most common format for a printable multicolor 3D model is .obj, as it defines both the geometry and is accompanied with the textures whose location is defined on the model using an .mtl file (which is automatically created upon export).

For the multicolor information to be interpreted, an image file must be included with the file, which will be used as the texture of the 3d model.

To export a 3D model as an .obj head over to File / Export / Wavefront (.obj)

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In the exporting options, choose “selection only” and choose “copy” in path mode. This will ensure that all of the files you’ll need to for a successful multicolor 3D print will be included in the location you’re creating. After that, name the file and click “Export OBJ”.

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  • .dae File Format

The Collada format can be a good alternative to .obj if you have problems during the export. With .dae files, the UV mapping texture and material geometry information are included in the file. As for .obj files, texture files are needed and they need to be zipped with the .dae file. The difference is that there is no need to add a .mtl file.

To export in .dae choose the model you’d like to export and go to File / Export / Collada.

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In the export options, choose “selection only” and choose “copy” in path mode. This will ensure that all of the files you’ll need for a successful multicolor 3D print will be included in the location you’re creating it. After that, name the file and click “Export COLLADA”.

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