When you create a 3D model in software, you save that model as a 3D printer file, and there are several file formats to choose from.
The most common 3D printer files are STL, OBJ, AMF, and 3MF. While each file format stores information about your model, they differ in the depth of information they capture, making them suited to different applications.
Which 3D file format should you choose? This article provides tips to help you choose the best file format for your requirements.
Let’s jump in!
What is the role of 3D printer files?
First, let’s cover the basics.
3D printer files store information about your models, such as their geometries and visual characteristics. This file provides slicing software with the details it needs to turn design data into instructions for the 3D printer.
The depth of detail is file-dependent because some file formats describe more data than others. For example, STL files describe only a model’s geometry, while OBJ 3D printing files also describe a model’s material and texture.
Ditch the superiority complex
Just because a specific file format captures more information about an object does not mean it is better for your intended application. There is no good or lousy format – only the most suitable format for the job.
For instance, OBJ files support polygonal faces that allow a close representation of the original geometry – perfect for detailed models. STL files do not support this, only storing objects as sets of vertices joined by edges – perfect for basic models.
STL is best for basic shapes and objects
An STL file saves your 3D model as a surface of geometrical shapes, creating a triangular mesh. It doesn’t store information about texture, colour, or polygonal faces, but it reliably covers the basic geometry of an object.
STL files are simple, lightweight, and translate into excellent print quality because every 3D printer on the market supports them.
Recognise when you need “more” data
Because STL files only store the external surface and shape of 3D models, they are unsuitable for complex shapes and details. For example, STL does not reliably translate gaps and overlaps of joining surfaces.
For complex objects, you should choose a 3D printing file that captures more detail, such as OBJ, AMF, or 3MF.
Understand the main alternative file formats
OBJ, AMF, and 3MF are the most popular alternatives to STL when objects require more data or when the hardware (the 3D printer) manages complex files better.
Here’s a brief synopsis:
OBJ files store geometry, colour, texture, and material data, with colour and texture stored separately in an MTL (Material Template). You can choose the way the geometry of your model is encoded using tessellations and introduce free-form shapes and curves.
The downside to OBJ is colour and texture data is stored in a separate file, and not all 3D printers support the file.
Like STL, the AMF (Additive Manufacturing File) format stores data with triangulation. However, the triangles in AMF can curve, and you can store colour, texture, orientation, and lattice data in one file for complex objects.
With the ability to store all possible object data in a tiny file, AMF is a replacement for STL. However, it has limited support.
3MF was borne from the slow adoption of AMF, created by some of the biggest names in 3D printing, including Autodesk, 3D Systems, and Microsoft. 3MF captures the same data as AMF but is more widely supported.
AMF and 3MF are interchangeable but also technology-dependent. Go for whichever format your 3D printer supports.
Find out more
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