FreeCAD and Mesh Import/en

Operations after Import
After import the model is (for FreeCAD) just an assembly of faces. You might want to convert the model into a shape FreeCAD can recognize and that could be altered in FreeCAD.

To do this:
 * Switch to the Part workbench
 * Select the mesh, and go to the Part menu --> Create shape from mesh
 * Click OK to the dialog
 * Select the newly created shape
 * Go to Part --> Convert to solid
 * Select the newly created solid
 * Go to Part --> Refine shape

The last step is not necessary, but it will clean the solid of most of its residual edges on planar and cylindrical surfaces.

I get the error message "cannot convert because shape is not a shell" ! What now ?
Well, your shell seems to have errors, maybe it is not closed (has holes). Since the capabilities of the mesh workbench in FreeCAD are a little limited at the moment, you might want to try examining and repairing of your model with third-party software. After doing that, you may try importing and converting of your model again.

Which programs can I use for examining/repairing of my mesh model ?

 * Meshlab
 * License: Open Source (GPL V2)
 * Runs on Windows 32/64 bit, Linux and Mac OS X


 * netFabb basic
 * License: Freeware
 * Runs on Windows XP/7/8, Linux and Mac OS X