The most common reason an STL file may be not quite right is a mechanical connection where some piece isn’t quite as the designer expected, so the 3D model that interfaces with it no longer fits.

Find out what is an STL file and how you can open and view an STL file with .stl extension in Windows 10. It is native to the stereolithography CAD software.

Worse still, as in our hypothetical example, there are no definition about how the triangles relate so you can create “bad” STL files. Even properly formed files can be tough to work with.