Person formatting 3d printing files on laptop

If you’ve been downloading 3D models or just starting to design your own, you probably encountered different file formats. While STL is the most common, there is OBJ, G-Code, 3MF, and more. Learn the differences between these file formats and how they affect your 3D printing.

1. STL

STL is the oldest and most common file format. Known as Stereolithography, it was developed in the late 1980s and it is still widely used today. If you’ve been designing models using a Computer-Aided Design (CAD) program, this is the file format it generates. STL can be edited and repaired by programs, such as 3D Slash, Blender, MeshLab, FreeCAD, SketchUp, and SculptGL.

How STL files work: It simplifies 3D surfaces by “tiling,” rendering the surface into a series of small triangles. Uneven and curved surfaces render more tiles. The more tiles a model has, the larger the file size is. 

2. 3DS

3DS is a simple file format that stores only basic information about the 3D model. such as the animations, scenes, geometry, and appearance (colour, texture, material,... etc.). As such, it is compatible with most CAD programs, including MeshLab, SketchUp, TurboCAD, Blender, and more.

How 3DS files work: 3DS files are made up of “chunks” of data that store an ID and length description. Each chunk contains the lighting, shapes, and viewing information of the model. 

3. OBJ

OBJ is the second-best file format next to STL. It was created to improve STL in terms of encoding smoother surfaces with fewer tiles using other polygons along with triangles in rendering the surface. It also stores material, texture, and colour information when the file is associated with external MTL and image files. OBJ files can be opened with Blender, MeshLab, and AutoDesk Maya 2013.

How OBJ files work: Just like STL, it renders the surface into tiles of small triangles as well as other polygons for smoother surfaces. It also supports colour and material information. Therefore, OBJ files have improved resolution and quality over STL but can cause the files to be too complex to rework. 

4. AMF

 AMF was designed to supposedly overcome the limitations of STL and OBJ to usher in a new world of 3D printing. Created in 2011, this file format is supposed to be less error-prone, faster, and able to store texture information, colour, and material without external files. It also encodes more sophisticated 3D shapes compared to STL and OBJ.

It seemed like a promising advancement. However, the adoption has been slow and the community still preferred both STL and OBJ. Some CAD programs and most slicers are compatible with AMF files.

How AMF files work: This XML-based file format uses curved triangles that closely follow the topology and linkage of 3D models. This gets rid of model issues common with STL. 

5. 3MF

Created by Microsoft in 2015, the 3MF is open-source software that aims to address the technical gaps left by AMF and foster collaboration among key users and the 3D printing community. Some of the biggest 3D printing names threw their hats in the ring, such as Ultimaker, Prusa Research, Stratasys, HP, and more.

How 3MF files work: Since the 3MF files are XML-based, they work similarly to AMF. The key differences/improvements are that they improved numerical precision and reduction of rounding errors. It also stores printing and slicer settings.

Less popular 3D printing file formats

There are plenty of other 3D printing file formats that are not as commonly used. Nevertheless, these are supported by slicers and can be easily converted into the commonly used formats above.

  • Unity
  • VRML
  • PLY
  • X3D
  • STEP
  • IGES

Toolpath file: G-Code

G-code is a common file that you’ll see when you’ve been browsing 3D model repository sites. If you’ve ever wondered what it means, we’ll decode it for you.

G-code is a file that contains all the end-product of the design and settings of the model, from the 3D model to the printer, materials and slicer settings. There are many other toolpath files out there, but G-code is the most popular. Simply, it means that when you download a G-code of a model, it’s already plug-and-print. You don’t have to worry about setting a parameter as everything’s all in there.

Alas, G-code files are not compatible with all 3D printers. Each toolpath file is created for a specific machine or material and it might be damaging to your 3D printer to use the wrong one.

Improve your 3D printing and modelling by learning more about 3D printing file formats! 

Learning more about 3D printing file formats can help you improve your 3D modelling and printing. Which of the file formats do you like the most? Sound off below. 

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