Knowledge Base Article

Know Your .stl

The way an .stl file is set-up is the single largest determinant of part surface quality. Please use the following instructions as a guide. An .stl file represents the surfaces of a solid or surface model with triangles.

Many engineers do not realize they should review the .stl file after they have saved their file out. Common understanding says the CAD manufacturer knows .stl setting best. This is not always true. Please review your saved .stl file in a third party viewer before sending it to Planet Proto. This extra step will help you always receive the quality parts you need. Please save these settings.

Note: Parts of different form and curvature may require different settings. You be the judge.

CAD systems will have several .stl options that impact the quality of the .stl file.

• "Deviation" changes the overall output, tessellation or number of triangles.
• "Angle Tolerance" changes fine details of your .stl file. And can significantly affect the size of your file.

Setting these values higher creates and .stl file with more triangles placed on the surface of the model. Here are some guielines:

• Simple or small CAD files create .stl files that may be around 500 KB in size.
• For small parts under the size of a 2” ball - increase the number of triangles (Deviation) – The number of triangles created will be manageable.
• Complex models with best quality .stl files may range from 4-12MB in size
• In larger parts over the size of a 2” ball limit file size to 12-16MB

Save the .stl file as a Binary file. Binary files are more compact and most commonly used.

Use Solid Viewer (free downloadable) to view your .stl file. If the file looks tessellated coarsely adjust your setting and review again. Using a CAD external viewer will usually best illustrate the course or fine tessellation of the file. Rotate the model to best see the triangles.

Quality levels for .stl files.