What is STL?
STL is the most common file format in the world of 3D printing. Interestingly, the definition of STL isn't entirely set in stone. By far the most people will tell you it stands for STereoLithography. However, you also hear that it stands for Standard Triangle Language or Standard Tessellation Language.
How does STL work?
STL files are known for being relatively small. You won't often see an STL file that's several tens of MBs. This is mainly due to how STL stores information. An STL file consists of the basic geometries of the design. Just the geometric data. If you zoom in, you'll see all sorts of tiny triangles tiled together. Nothing overlaps.
So, imagine you have a 3D model of a sphere. In an STL file, it's represented as a great many tiny triangles. Triangles always consist of 3 straight edges. So, for curved geometries, the mesh density is increased and the individual triangles are made smaller. Ideal? No. If you print a curve and look at it closely or feel it, you'll notice it isn't 100% curved.
Because STLs only contain geometric data (surfaces), you miss out on other important data. STL files are therefore purely for printing. Want to adjust the design? Change lengths? You can't. For that, you need, for example, the STEP file instead.
The history of STL
STL was developed by Chuck Hull at 3D Systems in the 1980s. He patented it in 1987. They wanted to develop a way to get 3D CAD models to 3D printers. The Albert Consulting Group realized this for 3D Systems by encoding the surface tiling of the 3D model. And voilà, functional STL files were born.
Frequently asked questions about the STL file format
How can I open an STL file?
You need to open an STL file in CAD software such as Autodesk Inventor or Solidworks.
What does STL stand for?
The definition of STL is, strangely enough, not entirely set in stone. Most people will tell you it stands for STereoLithography. However, some also say it stands for Standard Triangle Language or Standard Tesselation Language.
How do I export an STL file?
In most CAD software, you go to Export and can select .stl during the export process.
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