How to extract surfaces from an STL file?

[Brian_11]

I have created 3D surface of a helix (inside is hollow) which is an STL file. How can I extract surfaces using Creo Parametric? Notice that helix created as STL file is made up of meshes. Is it possible to extract cylinder surfaces from that?  The figure below is the 3D surface of the helix created.

 

[KenFarley]

From what I recall there are no surfaces in STL files. The STL file defines a large number of triangular facets that enclose a "solid" volume. If you want to obtain surfaces from a model, you need to use one of the other Save A Copy output file types, like IGES, or STEP, etc.

In essence, an STL file is equivalent to a file based solely of points.

[Brian_11]

I tried your suggestion and saved copies in IGES and STEP format. When I opened these files both of them were blank files (no helix).

[KenFarley]

I suspect that you are using an educational version of the program or some other "restricted" type of installation, and that it will not let you write STEP, or IGES, or other geometry files with surfaces in them. You are trying to write a file from Creo, yes?

I have numerous models of springs, which are more complicated versions of your helical sweep, and they are output to such files easily. For example, see the attached die spring...Die Spring STEP File Result

[kdirth]

It sounds as though @Brian_11  created the spring as an stl, not converted to stl.  Saving a file as a step or iges with a facet feature (the result of importing an stl) creates an empty file.  There are no surfaces or solids to export.

[Brian_11]

Yes you are right, I created spring as an stl file.

[tbraxton]

Restyle module has what you are looking for.

https://support.ptc.com/help/creo/creo_pma/r6.0/usascii/index.html#page/surfacing/restyle/About_Restyle_Reverse_Engineering.html