¿What means STL? 3D prining file format explained easy

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¿What means STL? 3D prining file format explained easy
May182018

¿What means STL? 3D prining file format explained easy

Just like when we print on paper we need a file that contains the information of the text to be printed, when we do it with our 3D printer we need a file that contains the three-dimensional information that will be reproduced.

This is where the STL files come in . These files contain information about a three-dimensional object. Unlike other 3D files , this format only contains information about the geometry of the surfaces of the object, leaving aside other information that does not intervene in the 3D printing process such as color or texture.

How to open stl files

What do the acronyms stl mean?

The true meaning of this extension is not very clear. The most accepted is ST ereo L itograpy because this technology was the first to adopt the format.

Other common meanings are "Standard Triangle Language" or  "Standard Tessellation Language"

How do STL files work?

Files with an STL extension encode the information of a 3D model . This is done through the process of Tessellation or mosaic in Spanish.

This process consists of dividing a surface into one or more geometric shapes so that there is no gap between them. It is very similar to seeing a tiled wall. This process can be done with very simple or very complicated forms, the triangle being the form used for the STL files

Who invented the STL format?

If you have read  our article on the history of 3D printing, the name of Chuck Hall will sound to you. Chuck was the inventor of the first stereolithographic printer .

How to view stl files
Chuck Hall creator of the STL format

The STL format was the result of searching for a type of file with which these 3D printers could work and the mosaic division of 3D surfaces was the way to achieve it.

The way to do it is as follows. Imagine that we want to encode the information of a cube using this technique. We can divide each face of the cube into 2 triangles and since the cube has 6 faces this will leave us with 12 triangles.

how a stl is generatedstl for 3d printing
Division in triangles of a cubeDivision of a complex model

Each of these triangles, also called facets are those that will be saved in the stl file. With this we manage to reduce the information necessary to store the cube, since it will only be necessary to store the position of each of the points that form the different triangles and a normal vector to each of the surfaces that should point away from the model.

For more complex models the technique remains the same, being able to cover the entire surface with small triangles. The more triangles our stl file contains, the more defined the model will be. We can match this to the pixels in a digital image.

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ASCII or binary coding?

The STL files allow us two ways to store information, ASCII or binary. In both cases the information stored is the same, the coordinates and the normal vector that we defined earlier.

ASCII encoding generates files of greater weight than binary. This is because in ASCII the information for each triangle is stored in a long text string while in binary it is stored by a 32-bit number.

The rules of the STL files

There are a series of rules that the STL files must comply with:

  • Each triangle must share two vertices with the nearby triangles
  • To avoid problems of corrupt files, the orientation of each triangle must be specified in two ways.
  • All the coordinates of the vertices of the triangle must be positive.
  • It is recommended that the coordinates of the vertices be ordered in ascending order on the Z axis. This, for example, helps the slicers to prepare the model for 3D printing.

How are STLs prepared for 3D printing?

In order for a 3D printer to understand an STL file it is necessary to use a slicer that is a program that transforms the file information into instructions for the printer.

In this process the stl file is divided into layers and each of these layers is transformed into the information that the printer can understand.

Cure for 3D printing

Keep in mind that not all STL files can be printed in 3D. In order for these files to be compatible, they must meet a series of conditions. The first is that the file does not have a zero wall thickness. In addition, we must make sure that the triangles mesh of the STL file is fully closed.

At the time of printing we must also bear in mind that there must be a balance between quality and weight of the file. We already know that the more number of triangles the more definition our 3D model will have , but if the file is too heavy it is possible that our slicer can not with the file.

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Download STL to print in 3D

There are countless pages where you can get stl files ready to print, without a doubt our favorites are  thingiverse and myninifactory .

How to view STL files?

STL files are very common and most 3D design programs let you see and work with them without problem. If you want a quick online application you can try https://www.viewstl.com/

And that's all for today,

Greetings and see you printing

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