3D Printing Tutorial : Rhinoceros 3D
This 3D modeling software tutorial is written and designed to provide 3D printing enthusiasts with accurate instructions for designing 3D files that are 3D Printable thanks to Rhino 3D CAD software.
In this 3D CAD tutorial, you will learn the best practices for modeling, correcting and exporting an object for 3D printing using Rhino software. At the end of this Rhino 3D tutorial, you will learn how to:
- Design a printable 3D file
- Manage and export valid 3D files for 3D printing from Rhinoceros
- Avoid mistakes that occur when designing 3D files for 3D printing on Rhinoceros
Then, you will be able to upload your 3D file on our website and 3D print it!
Rhinoceros (Rhino) is a 3D modelling software specialized for free-form NURBS (non uniform rational B-spline), created by Robert McNeel & Associates. NURBS is a mathematical model that renders curves and surfaces in computers graphics. This mathematical model offers great flexibility and precision in 3D modelling.
Rhinoceros is a CAD software commonly used for industrial design, architecture, marine design, jewelry design, automotive design, CAD / CAM, rapid prototyping, reverse engineering, product design, furniture design, as well as the multimedia and graphic design industries. Product design’s easy thanks to this 3D modeling tool. Rhino software is also great to create CAD models for rapid prototyping with 3D printers. Indeed, Rhino models can be saved in a file format compatible with 3D printing.
A basic understanding of Rhinoceros is required in order to get the most out of this CAD software tutorial. Rhinoceros provides lots of great videos and tutorials on its website for getting started with Rhino.
You can buy Rhino 3D or download a 90 days trial version of Rhinoceros V5 for free. You will also find some plugins for Rhino 3D that will help you get a great Computer-Aided design experience and create the best CAD models.
Rhino Models: Design a printable 3D file
1.1. Before starting to model
Before you start 3D modelling anything using Rhino there are some factors that should be considered.
Key concepts for 3D modelling with Rhino
Rhinoceros works with a 3D modelling category called NURBS which is different than regular mesh 3D modelling. However for 3D printing in Rhino it is still necessary to create a mesh after the 3D modelling process. For this reason it is important to keep in mind and clarify some basic 3D modelling concepts.
NURBS 3D modelling concepts
- Curve: are basically the points, lines and segments that make up the sketch model.
- Surface: is a plane without thickness created between a group of closed curves.
- Polysurface: is a set of multiple contiguous surfaces that build a volume.
- Solid: is a completely closed and joined polysurface that create the 3D model. It is different from a mesh.
Mesh 3D modelling concepts
- Vertices: is a position along with other information such as color, normal vector and texture coordinates.
- Edges: is a connection between two vertices.
- Faces: is a closed set of edges that form a plane without thickness.
- Polygon: is a coplanar set of faces that build an open or a close volume.
- Mesh: is a collection of vertices, edges and faces that define the shape of the 3D model. It is different from a solid.
A solid in Rhino is built with NURBS, which is different from a solid built through mesh 3D modelling. Knowing the difference between these two 3D modelling approaches is important for a successful 3D printable model.
Global 3D printing 3D modelling process with Rhino
Objet dimensions and measures compatibility
An important factor to consider before starting your 3D model is the size of the object relative to the professional 3D printer that will be used to produce the piece. For example, if the model is bigger than the 3D printing area, the model must be adjusted.
Also the desired dimensions of the piece should be coherent with the dimensions used while 3D modelling, as well as the units settings of the file that suits better to the project (inches, centimetres, millimetres). This can be found at ‘File/ Properties/ Document Properties/ Units’.
You can work with the most suitable units for you or for the project while 3D modelling. However before exporting you must always switch the units to millimeters and allow Rhino to scale the model.
Rhino unit settings are always interpreted as millimeters when imported into other programs. So, for example, if you modeled a part of 5 cm × 5 cm × 5 cm using centimeters as a unit, you will obtain measurements of 5 mm × 5 mm × 5 mm when exporting your model in STL. This is why you must change the units to millimeters no matter what unit of measurement you used to begin your model.
Grid adjustment and measurement
It is important to be aware of the measures at all times while 3D modelling as this will allow you to have absolute control over the size of your model. The main tool in Rhino used to visualize the size of your objects is the display grid in the background of the viewports. The grid allows you to work precisely using the “Grid Snap” and the “Linear Dimension” tool.
You can set up and personalize your grid at ‘File/ Properties/ Document Properties/ Grid’.
The “Linear Dimension” tool is Rhino’s technical drawing tool and can be used to find a precise measurement of the model. You can find it at Dimension/ Linear Dimension.
The dimension will appear on the arrows bar that was used to set up the file units, after selecting a starting and ending point for the line.
It is recommended to take a look at the tolerance settings file. This can be found at ‘File/ Properties/ Document Properties/ Units/ Absolute Tolerance’.
The 3D file tolerance should be set up depending on the model size and 3D modelling units. For example a 0.001 mm tolerance for a model with a size of 500 mm × 500 mm × 300mm will be an exaggerated tolerance. Instead a 0.001 mm tolerance for a model with a size of 70 mm × 70 mm × 70mm will be reasonable.
This aspect is also relevant for the mesh creation that will be explained later in this tutorial.
Real time tool verification
It could be also useful to turn on the Check New Objects tool by typing it in the command line “CheckNewObjects”. This command will constantly check every geometric figure created to verify if it is valid (not bad) and pops up a message when the figure created is corrupted.
1.2. Proper 3D modelling for 3D print
1.3. Color and textures for full color printing
Manage and export valid 3D files for 3D printing from Rhinoceros
2.1. 3D model analysis
The simplest way to identify an open
When an object is made of an open
If the model stays closed, you will see “No objects added to selection” in the command line.
By doing this, you can find out which object is made of an open
Once you have the isolated object you can proceed to do the naked edges detection.
Edge analysis for naked edges
The edge analysis tool will help you detect where and if a
This command will light up the open contour according to the selection color in the edge analysis box.
The “select bad objects”
To have more detailed information about a bad object, you can run a diagnostic using “Check objects” available in the main menu under ‘Check objects’. A popup window will give you more information about the model e.g. if there is any bad geometry or “Rhino
You can select the model and go to properties in the right column to select
2.2. Fix NURBS 3D model
- First of all, identify the bad surfaces and hide everything else temporarily. You can separate the bad surfaces from the polysurface using “Bad Surfaces Extract” by typing “ExtractBadSrf” in the command line .
- Once you have the bad surfaces isolated, proceed to restore the edges of the surfaces to their original state before they were joined – with the command “Rebuild Edges”. You can find this in the main menu ‘Fillet Surface/ Rebuild Edges’ or typing in the command bar “RebuildEdges”. This operation will detach the surfaces so you can rejoin them again. In some cases, this might work. After this operation, you should check if the surfaces are repaired or if there are at least some of them fixed.
- If the surfaces were not completely fixed, you can select a bad surface and remove the trimming boundary from a surface using the command “Untrim” followed by “keep trim objects”. This is available in the main menu ‘Fillet surface/ Untrim’ or typing in the command bar “
Untrim”. Select the trim curve and trim itagain. Then check if the surface is no longer a bad surface. You should apply the same operation to the other bad surfaces. For the last part,try to unhide everything and make them all join up again. Check for bad geometry with “Check objects ” .If this does not work, it is usually because the join operation is trying to force things together that do not fit correctly. If so, it is recommended to find the bad surfaces and analysethe union with the contiguous surfaces.
2.3. Create and export a mesh
- Density: 0.0
- Maximum angle: 0.0
- Maximum aspect ratio: 0.0
- Minimum edge length: 0.0
- Maximum edge length: 0.0
- Maximum distance edge to
surface: “The same as the tolerance file” (tolerance settings)
- Maximum edge length: 0.0
- Minimum initial grid quads: “Variable depending on how the mesh looks”
2.4. Correct mesh for 3D printing
Closed and compact mesh
The mesh object must be compact meaning no vertices, edges or faces around the main model. All the pieces that make up the model should have a volume, there can’t be faces without any mass.
A 3D printable mesh is a correctly manifolded mesh. The term manifold defines a mesh in which all its triangular edges are directly and individually connected to one another creating a closed volume.
Non-manifold errors are generally produced by the following reasons:
- Several faces share one edge
- Several faces share the same point or vertex
- There are some unnecessary faces intersecting the main body of the model or at the interior of the model
Coherent mesh orientation
The faces that compose the mesh may not have the same normal orientation. That means that while one face
One single shell
Every part that makes up your digital model needs to be made out of just one shell. When you select a single part of your model, you usually should see in the command line “1 mesh added to selection” this
2.5. Mesh analysis
Avoid mistakes that occur when designing 3D files for 3D printing on Rhino
At Sculpteo we have developed some great automatic mesh repairing algorithms that you can easily access online through the upload environment. We can proudly say that these methods succeed in almost all cases in repairing common mesh problems, but as they are automated repairs, you might want to have better control on how your mesh topology should be modified following any repairs. Therefore when dealing with isolated and detectable errors, it is better to manually repair these errors yourself on your 3D modelling software as in rhino, the necessary tools are provided.
The reason for manually troubleshooting errors is that no automated algorithm knows your mesh as accurately as you do.
Next, the tools Rhino provides to solve the most common problems with invalid meshes will be discussed in the coming paragraphs.
3.1. Mesh reduce
If your mesh’s ‘Number of Polygons’ is more than a 1.000.000, it will be quite difficult for Sculpteo to handle it which also means it contains unnecessary details. Therefore, you need to reduce this number through the “Reduce mesh” command .
You will have to find a good balance between your model quality detail and the polygons number because the more you reduce the mesh the more it will become faceted.
3.2. Mesh orientation unification
The faces belonging to the same shell of your model might not have a coherent orientation, which means that the normal direction of your faces are not the same as it was explained before in the “Coherent Mesh” section. In order to fix this issue select your model and use “Unify mesh normals” tool this will put all the normal direction to the same side and will eliminate the problem.