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25/10/2019 PROJECT DATE 25/10/2019 PROJECT DATE 25/10/2019 PROJECT DATE 25/10/2019 PROJECT DATE 30/10/2019 PROJECT DATE 30/10/2019 PROJECT DATE 06/11/2019 PROJECT DATE 20/11/2019 PROJECT DATE 20/11/2019 PROJECT DATE

1. MODEL GEOMETRY

NAMES
3D PRINT ESSENTIALS

LOCATION
ONLINE

DATE
TBC

DURATION ONLINE
TBC

DURATION PRACTICAL
TBC

MANDATORY REQUIREMENTS
RHINO QUICK START

SOFTWARE REQUIREMENTS
RHINOCEROS 7

PRUSASLICER

LEARNING OUTCOMES
TBC

CHALLENGE
TBC

In the Fabrication Laboratory we have 3 types of 3D printer available for use.
We have both plastic and plaster printers, but they work in the same way, both are additive processes that slice a 3-Dimensional CAD Object into layers before printing it
layer-by-layer.

MODEL GEOMETRY:

We recommend using rhino to model your geometry. However, you can use any CAD program you are familiar with. Below is a template file with build volumes and some useful help built in.

1. IS YOUR GEOMETRY PRINTABLE?

When designing your model geometry, it is very important to consider that 3D printers have limitations and your model should be designed around them.
The maximum build volume is 250x210x210 mm

Good Geometry

A good geometry is a geometry that has been designed considering the 3D printers limitations.

Bad Geometry

A bad geometry is a geometry that has been designed without taking into consideration the 3D printers limitations, resulting in an unprintable model. This is common when you have a very complex geometry.

2. ARE THE ELEMENTS OF YOUR GEOMETRY TOO THIN?

Each element of your model should not have a thickness less than 0.4mm for them to be possible to be printed. For best results a minimum of 0.8mm is recommended.


3. IS YOUR GEOMETRY WATERTIGHT?

When creating a 3D file for printing, it is important to remember that in order for the machine to be able to process what is on the ‘inside’ and ‘outside’ of your object, the object needs to be ‘watertight’. This is done by making sure your geometry is free of any gaps in its surfaces.

To ensure that your geometry is completely watertight, and has no gaps or issues, you must run the Rhino command ‘ShowEdges’, this will check for ‘Naked Edges’ and ‘Non-Manifold Edges’. This will highlight the problematic edges in Rhino (usually with a purple line). These need to be fixed before you export your object as an .stl file. Download the guide for guidance on fixing these problems.

4. DOES YOUR MODEL NEED SUPPORTS?

When your model has an overhang or bridge which is not supported by anything below, you might need to use 3D printing support structures to be able to print it, these ones are generated by the Prusa Slicer software.

Consider that adding support will greatly increase your printing time, and supports can, at times, be difficult to take out of your model.

You might be able to print overhangs with angles of less than 45º without using support. And just like overhangs, not all bridges require support. The rule of thumb is: if a bridge is less than 5mm in length, the printer may be able to print it without requiring 3D printing support structures.

5. EXPORT AS .stl

Create a mesh - When using Rhino you model with NURBS Surfaces, an .stl file is a MESH file type which is what is needed for 3D Printing, getting from one to the other translates free-form NURBS into triangulated meshes.
To create a mesh from your Rhino NURBS, select your object and use the ‘Mesh’ command. You will be given options for the number of polygons that your mesh will be made from, more polygons = better translation but bigger file sizes.
Once you have your mesh, export it as an .stl file from Rhino. If you have multiple parts or components, each MUST be saved as a separate file, as groups of objects cannot separately be edited later on. To save your object, select it, use the ‘Export Selected’ command, and then on the file type drop-down, select the stereolithography option (.stl)

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