In order to manufacture anything on 3D Printer, you first need a 3D model (a computer file that defines the shape of an object). There are various file types capable of containing 3D objects. We will take a look at those that are the most suitable for 3D printing. And we will also take a look at different qualities of 3D files to ensure they are printable. Not every 3D model can be 3D printed, it the same as for example architectural sketches. Not everything that is sketched on a paper can be materialized into a stable structure. 

TYPES OF 3D MODELS

The models can be divided according to whether they are usable for printing full-colour models or whether they do not carry colour/texture information.

 

Models for 3D printing without texture

The most commonly used file type for 3D printing is STL (.stl) which is a polygon-based file format. The surface of a 3D model is represented by a set of triangles (polygons). Polygon 3D model can also be represented by rectangular polygons called quads. 

How are STL files (3D models) obtained? If you already have your 3D model created in any of the common engineering programs, like for or example Solidworks, Inventor, Rhino, Fusion 360, you will typically just export your project as an .STL file. 

You can also download a vast amount of ready to print STL files on sites like thingiverse.com. Or you can download CAD models from sites like grabcad.com and convert them to STL – for conversion you can use, for instance, Workbench) 

Last option is to use a 3D scanner to digitalize an existing physical object. 

WHAT TO DOUBLE CHECK BEFORE 3D PRINTING AN STL FILE

For checking your STL file, you can use a free version of Autodesk Netfabb. (You will get a 30-day trial version of Netfabb Premium, which then automatically switches to free Netfabb Basic). .

 

1) SCALE

Sadly, there is no information about units contained in STL file. You can read from the file that the 3D model is, for instance, 200 x 150 x 8, but there is no additional information. So, you can’t tell if the 3D model was created in mm, inch, etc. When you want someone else to print your STL file, it is wise to specify the correct units/dimensions to them clearly. A common error occurs when you create your 3D model in inches, and the 3D printing studio uses mm as a default. That means your part could get 25.4x smaller. That’s a big error. Imagine you would like to get a prototype of your screwdriver design (in real life dimensions), but instead received a prototype so tiny that even a Lego mini figure would have problems holding it. 

 

Thankfully, most 3D printing services will include the dimensions of your 3D model in a quote for the print, so you can double check if these are correct prior to pushing the “print” button. 

 

2) RESOLUTION

You should always double check that your STL model is exported with a sufficient resolution of the polygon mesh (that applies to .3mf also). Too low of a resolution will degrade your design. However, too big resolutions can result in an enormously huge file that will be problematic to handle. When exporting an STL file, you usually have an option to select Binary or ASCII format. Binary format results in a much smaller file size so this option is used primarily.