Back to 3D Powder Printing
When using a surface modeling program, only surfaces that form a closed object
can be 3D printed. The closed surface model must be converted into a "solid" object, which is described by the STL file.
- Prior to building any geometry go to Tools > Options....
- In the Rhino Options window navigate to Units.
- Set Model units: to Inches.
- Hit OK.
- Naked Edges are edges where the seam between two surfaces is imperfect. This either indicates that there is a hole in the model, or that two surfaces are not lining up properly, in which case one of the surfaces will need to be rebuilt relative to the other.
- To check for naked edges, select the polysurface in question and key in ShowEdges. A window titled Edge Analysis will appear.
- Select Naked Edges.
- A naked edge may be the result of a surface operation that approximates edge curves, such as a Network Surface (Surface > Curve Network). It is recommended to rebuild these using Edge Surfaces (Surface > Edge Curves). It may also indicate that there is a surface missing from the polysurface, creating a hole in your model.
- Non-Manifold Edges are edges in contact with more than two surfaces. This typically indicates one of two things:
- There is an extra surface within the model that is not necessary for defining its boundary.
- Two or more polysurfaces coincident along a single edge have been combined with a Boolean operation, which is permitted in the software but is not a sound way to model - the 3dprint will inevitably crumble along such joints.
- To check for non-manifold edges, select the polysurface in question and use the ShowEdges command. A window titled Edge Analysis will appear.
- Select Non-Manifold Edges.
- The following example was fixed by adding some "mass" to the non-manifold joints in question:
Surface Normal Direction
- Surface Normals must be pointing away from material that you wish to print and toward open space.
- If you have shelled your model, there will be one set of surface normals pointing to the exterior space and one set pointing toward the interior void.
- To check surface normals, key in Dir (for direction).
- Left click on-screen to uniformly change the direction of all surface normals and right-click to exit the command.
- To shade inverted normals go to Tools > Options... > Appearance > Advanced Settings > Shading.
- Set Backface settings to Single Color for all backfaces.
- Customize the Single backface color.
- To fill a mesh hole use the FillMeshHole command.
- Select a mesh edge from the hole to have it automatically filled.
- Though improvements have been made in Rhino version 5.0 for shelling surface models with the OffsetPolysurface command, there is typically a better result gained by first meshing the open polysurface model with the Mesh command and then shelling it using the OffsetMesh command.
- To create a "watertight" mesh be sure to check Solidify.
- Based on the geometry being shelled and the shell thickness, the model may self-intersect.
- To ensure that your mesh is appropriate for a stereolithography 3D print, select the mesh. (If you have already exported an *.stl file out of Rhino, you may simply File > Open it back up.)
- Key in CheckMesh.
- This tool will check for all common mesh errors by displaying an on-screen report.
- Check/repair meshes
- Calculate your part's volume by selecting any closed polysurface(s) or mesh(es) and using the Volume command.
Export as STL
- Go to File > Save As...
- In the Save window select Stereolithography (*.stl) under Save as type:.
- Hit Save.
- In the STL Mesh Export Options window hit the Detailed Controls... button.
- The Polygon Mesh Detailed Options window allows you to control all common mesh attributes.
- Help Mesh Settings Page
Import into ZPrint
- For powder printing, the file must be converted into a *.ZBD file.
- *.ZBD files are created by importing *.STL files into the
ZPrint software, available on all DAAP CGC PC machines.
- Launch the ZPrint application.
- Importing CAD to ZPrint
Back to 3D Powder Printing