AMF File Format – Should You Use It For 3D Printing?
The 3D printing industry is quite unique in that it suffers from way too many file formats. This mainly stems from the early years of 3D modeling when several software programs were developed, each introducing a different file format that is also proprietary.
Most people have gotten used to 3D printing with STL files. However, there is still a vocal minority out there that espouses the benefit of printing with AMF files instead. What exactly is the AMF file and what makes it special? Is making the shift to AMF files before 3D printing something that you should consider?
What are AMF files?
The Additive Manufacturing File (AMF) is a relatively new file format for 3D models, having been developed only in 2013 by the American Society for Testing Materials (ASTM). It is a file format that was created specifically for the growing industry of 3D printing and additive manufacturing, thus the name.
At the time of its development, STL files were already very popular for 3D printing. An objective of the AMF file was to address the drawbacks of the STL file. In many respects, the AMF file was an upgrade and was even prematurely dubbed “STL 2.0”. Instead of representing surfaces as a tessellation of flat triangles, AMF files were able to represent them as curved triangles.
AMF files are also capable of storing texture, color, and material data – something that was not possible in STL files. All this additional data was reconstructed in XML.
AMF vs STL vs OBJ
Right now, the landscape of 3D modeling and 3D printing is dominated by two file formats – STL and OBJ. Of the two, STL remains dominant, particularly in 3D printing. To better understand the value of the AMF file format, it is good to compare it to either STL or OBJ.
STL files have become popular mainly because of how small they are. This is achieved by representing the surfaces of a 3D model as a series of tessellated triangles. The number and density of triangles in any single 3D model can depend on its complexity, but this is generally considered a simple way of representing a 3D model.
An STL file contains information only on the geometry of a 3D model, including its shape and size. Information on the color and texture is discarded during conversion. For the most part, STL files are difficult to edit or modify because they are only approximations of the source 3D model.
OBJ files are considered to be closer representatives to the actual 3D model as it was modeled or sculpted. Surfaces in OBJ files are represented by Non-uniform Rational B-spline (NURBS) or simply “splines.” These are smooth lines that can curve in any manner and intersect with each other as “knots.” Thus, curved surfaces look a lot smoother in OBJ files are fine details are preserved better.
OBJ files also contain information about a model’s color and texture. With the original mesh intact, OBJ files generally can be freely modified. For professionals and organizations, OBJ files provide a much more appropriate platform for collaborative work.
With all the extra detail, OBJ files have a size penalty. They also take a longer time to render and are generally not in a user-friendly format. For general 3D printing use, working with OBJ files is considered by many to be impractical.
Just like OBJ files, AMF files can store data on color, texture, and other aspects beyond geometry. This adds a bit of complexity to AMF files and makes them more suitable for professional work.
AMF files also have a bit of similarity with STL files. Just like STL, the surfaces of AMF files are represented by tessellated triangles. However, the triangles in AMF files can curve to follow the geometry of the model. This results in more accurate model representation, avoidance of errors and inconsistencies common in STL files, and the possibility of using a smaller number of triangles.
This means that AMF files can be smaller than STL files and much smaller than OBJ files while retaining an equal or higher volume of data.
Drawbacks of using AMF files
All things considered; AMF files are technically superior to STL files. For this reason, you may wonder why AMF files are not more common in 3D printing.
The short answer is that adoption of the AMF file format has been slow, mainly because of how popular STL files have already become. Many of the slicers used in 3D printers, as well as 3D model-sharing sites, work with STL files by default.
You can actually search for AMF files in Thingiverse or CGTrader if you prefer working in this file format. The AMF files are there, just don’t expect a huge number of them.
Although the AMF file format was developed to be the new standard in 3D printing, it did not really catch on quite as well as intended. Now that newer and better file formats are coming up, it is becoming even less likely that AMF will become nearly as popular as STL.
3D printing with AMF files
The good thing about 3D printing file formats is that you don’t necessarily need to stick to just one. For the most part, you will still be using STL files because they are so easy to find and are good enough for quick 3D printing. Finding downloadable AMF files is tough, but the rare finds are usually worth the effort.
If you make your own 3D models, then exporting them as AMF files is worth exploring. As mentioned, AMF files have better fidelity in terms of surface and detail resolution. You can also make AMF files smaller than their STL counterparts. Fortunately, most CAD software support exporting and editing AMF Files. If you plan on making multi-color 3D prints, then exporting an AMF file seems a suitable solution.
AMF files may not be universally supported, but most of the brand name slicers and 3D printers support the format. Even with other XML-based file formats coming up, AMF will likely remain a legacy file format that should remain usable at least for the next decade or so.
AMF is not exactly one of the more well-known 3D printing file formats, but it does have its share of supporters. This isn’t surprising. The AMF file format is perfectly capable and quite powerful, which can be surprising for people who have not heard of it.
With new and better file formats being developed, the window for widespread adoption of AMF is closing. There likely isn’t going to be a resurgence of interest in the use of AMF files, but it’s fun to experiment with it and see how much better it is than the mainstream STL file format.