When you go and download files for 3D printers from sites such as Thingiverse or YouMagine, you usually get a .stl file. As with many file extensions, most do not ask where the abbreviation stems from and what the format actually does as long as it just works, right?

Well, this article is a bit technical. We are going to learn about file formats after all.

In May, the 3MF Consortium was established. Its goal is to create a new file format to suite the whole process from 3D modeling to manufacturing. Initially, the following seven companies make up the consortium: Microsoft, HP, Shapeways, Autodesk, Dassault Systems, netfabb and SLM Solutions.

But what is wrong with .stl?

“But my printer works fine with .stl!” – you might shout in anger, shaking your fist in the general direction of the God of 3D printing, if he/she/it exists. A new file format? That propably means you need to buy a new printer, new software, something else. They just want to squeeze the money out of everyone who wants to 3D print, right?

Not necessarily. The 3MF members have agreed to make their necessary patent claims available for implementations of the 3MF Core Specification and 3MF Materials Specification on a royalty-free basis. Also, the 3MF Consortium launched a GitHub page where the beginnings of the file format are documented for the public. This does not necessarily mean that .3mf will be free to use, though. It also does not mean the whole 3MF format specifications will be available as an open-source standard. It might be a part of the strategy to lull everybody into a sense of security. Microsoft is known and feared for business methods that put their competitors under pressure. There are other ways than collecting royalty fees to handicap third parties, and we can just wait and see what will actually happen.

So what do we need a new format for?

“’To empower people, maximize productivity, and unlock the full capabilities of this technology” according to Gavin Gear, Senior Program Manager at Microsoft.

“Full capabilities” is the clue to understanding the need for a new file format. Created in the 1990s by 3D systems, the .stl format works in a way that every object is described by its surface geometry. Every object you save as an .stl is saved as a cluster of triangles in a Cartesian coordinate system. That means, for example, that you do not get perfectly round shapes. The more you zoom in on the file, the clearer you will see the triangles the seemingly round shape consists of, just like in your old computer games, where everything was made of polygons. The new format will not only consist of polygons, but depict every curvature and rounding like it should.

At the moment, your CAD software usually works with other formats than .stl for a variety of reasons. Most construction software can actually output .stl files though. Your printing software takes the .stl files and slices them, in most cases to G-code format; these sliced files which can have numerous endings, such as .mpt, .mpf .nc and others. The .3mf format will put an end to the variety of files needed for the whole process of construction, modification and manufacturing of 3D models, according to the consortium.

Richer on information, the new format includes information like color, material and surface structure as new properties that are included in the file. (There is a file format already that can do most of this, but software and hardware giants often have a mind of their own about truly open and free standards.)

This allows for material mixtures being printed, for example mixing 50% red and 50% blue material to get a violet color, or a metal-ceramics compound for example. New features can be implemented according to the format´s specifications.

The biggest advantage the .3mf format will offer is its integration into Windows 10, which we may see as early as this July. 3D printing a file should become as easy as printing out a document, at least in regards to the software. 3D printing complex objects without the fuss of handling different file formats could introduce 3D printing into many new households.

With all those big players lined up, the 3MF consortium is possibly too big to fail. So say goodbye to .stl on the long run. And let’s hope existing 3D printers will be able to use the new format as soon as possible. The big players are in the game and they will make us play it their way.