What is an STL file format?

Format approximates the surfaces of a solid model with triangles

Posted on February 12, 2019 in design, stl

The STL file (standard tessellation language) format has become the Rapid Prototyping industry’s existing standard data transmission format, and this format is required to interact with Quick parts. This format approximates the surfaces of a solid model with triangles.

Are cad systems related to the STL files?

Almost all of today’s CAD systems are capable enough to produce an STL file. For the user, the process is often as simple as selecting File, Save As, and STL. Below are steps for producing high-quality STL files from a large number of today’s leading CAD systems.

Ideal measurements for STL files are available

As a general rule, options which enable changes such as Chord Tolerance or Angular Control will change the resolution on your STL file. The larger the STL file will be, the more triangles placed on the surface of the model. For simple geometry (not a number of curves), the file may only be a couple of hundred kilobytes. For complex models, the sizes of this range will be in between 1–5 MB will produce good parts. For many geometries, files larger than 5 MB are unnecessary and will often just result in more time to get your quote and parts back.

Rapid Prototyping processes ask for different dimensions

Also, for most Rapid prototyping processes and raw materials, the minimum feature thickness is going to be 0.020. Anything lesser then this feature won’t let you develop an STL file. It’s better to check your models and make necessary changes to critical features. Only High-Resolution SLA is the exception, which will make features down to 0.010 and the SLS Flex material, which needs 0.040 thickness to produce features in future.

Geomagic Design (former Alibre)

  • File
  • Export
  • Save As >STL
  • Enter File Name
  • Save


  • Your design must be a three-dimensional solid object to output an STL file
  • Make sure the model is in positive space
  • Set Facetres to 10
  • At the command prompt type STLOUT
  • Select Objects
  • Choose Y for Binary
  • Choose Filename

CadKey / KeyCreator

  • Choose Stereolithography from Export options
  • Enter the filename
  • Click OK


  • File >Export >Rapid Prototype File >OK
  • Select the Part to be Prototyped
  • Select Prototype Device >SLA500.dat >OK
  • Set absolute facet deviation to 0.000395
  • Select Binary >OK


  • Save Copy As
  • Select STL
  • Choose Options >Set to High
  • Enter File Name
  • Save


  • Right Click on the part
  • Part Properties >Rendering
  • Set Facet Surface Smoothing to 150
  • File >Export
  • Choose .STL

Mechanical Desktop

  • Use the AMSTLOUT command to export your STL file
  • The following command line options affect the quality of the STL and should be adjusted to produce an acceptable file
  • Angular Tolerance  -  This command limits the angle between the normals of adjacent triangles
  • The default setting is 15 degrees. Reducing the angle will increase the resolution of the STL file
  • Aspect Ratio - This setting controls the Height/Width ratio of the facets. A setting of 1 would mean the height of a facet is no greater than its width. The default setting is 0, ignored
  • Surface Tolerance -  This setting controls the greatest distance between the edge of a facet and the actual geometry. A setting of 0.0000 causes this option to be ignored.
  • Vertex Spacing  -  This option controls the length of the edge of a facet. The default setting is 0.0000, ignored


  • File >Save a Copy
  • Set type to STL
  • Set chord height to 0. The field will be replaced by minimum acceptable value
  • Set Angle Control to 1
  • Choose File Name
  • OK


  • File >Save As
  • Select File Type >STL
  • Enter a name for the STL file
  • Save
  • Select Binary STL Files


  • File >External >Save STL
  • Select Binary mode
  • Select Part
  • Enter 0.001mm for Max Deviation Distance
  • Click OK


  • File >Save As
  • Set Save As Type to STL
  • Options
  • Set Conversion Tolerance to 0.001in or 0.0254mm
  • Set Surface Plane Angle to 45.00
  • Save


  • File >Save As
  • Set Save As Type to STL
  • Options >Output As = Binary, Unit = Inches
  • Resolution > Custom, Deviation Tolerance = Minimum (Slide bar to right), Angle Tolerance = 5 degrees
  • OK
  • Save


  • File >Save As
  • Set Save As Type to STL
  • Save


  • File >Export >Rapid Prototyping
  • Set Output type to Binary
  • Set Triangle Tolerance to 0.0025
  • Set Adjacency Tolerance to 0.12
  • Set Auto Normal Gen to On
  • Set Normal Display to Off
  • Set Triangle Display to On


Oryginaly published by Makenica.com @ medium.com on Apr 7, 2018