What is an STL file?
.STL is the most common file format used in 3D printing. STL stands for STereoLithography, and is a file type which contains data of a 3D object’s layout, as generated by computer-aided design (CAD) software. Being one of the most widely used file formats for 3D printing, STL is found in use by hobbyists and professionals alike. STL files are important for 3D printing, as they contain the 3D model to be printed.
How do STL files work?
Objects in STL files are made up of connected triangles, making up the object’s surface. The higher the model’s resolution, the more triangles it must have. Though this will make the objects within appear higher quality, the file size increases with the number of triangles.
Why use STL Files?
In short, STL files are simple. You can make incredibly complex designs using only simple triangles.
STL files are powerful as they are scalable. This means you can make any 3D model in an STL bigger and smaller without losing much quality. They are also universal, working with virtually all 3D printers and CAD software. This also makes them easy to learn and then use.
Can I print any STL?
While all STL files you obtain here at Printable Scenery are ready for 3D printing, this is not the case for all STL files elsewhere on the web. Think of it this way: a Word document is designed to hold words and sentences. If the data within the file was just gibberish, you wouldn’t be able to understand it. In the same sense, data within an STL file must meet certain criteria for a printer to properly understand and output it.
3D models which are suitable for 3D printing must have a minimum wall thickness and be “watertight” in their design, with all surfaces properly connecting.
How do I print an STL?
To 3D print STL files, you will need some additional software. Known as a slicer, this software will convert digital 3D models into printing instructions for your home printer.
A slicer will reduce the model into horizontal layers based on your settings. It will also calculate how much filament or resin will be used, and the time taken to complete the print. Depending on what type of 3D printer you are using, you may need to add additional supports in the slicer. For resin printers it is advised to print the models at a 45 degree angle to minimise friction on the FEP screen, so supports are advised for the whole model. when FDM printing, overhanging or free-standing elements at more than a 35 degree angle will require supports to print.
Without supports, the printer will attempt to print where it should, but filament will warp or simply fall to whatever’s below. In this case, before you print any STL files you find online it’s best to give them a look over in 3D modelling software. This will stop failed prints costing you time and money.
When you hit the slice button, the program will convert the STL file into a format compatible with your printer. This can then be loaded into your 3D printer and the print started.
How do I open and edit an STL file?
If you just want to open and view and STL file, there are lots of file viewers available. These come as either online applications or desktop software to install on your computer.
Otherwise, there is software available for editing purposes. This software will allow you to change any qualities of a model to your liking, and even convert to other file formats. The most popular editing software are Meshmixer, Netfab, Blender and Microsoft 3D Builder. Editing may be worthwhile for some Printable Scenery models, like plane cutting a model when it is too large for your printer. You can read our article here on how to planecut using Meshmixer.
For reference on what to look for in a 3D printer, refer to our article on Buying a 3D Printer.