Creating a solid from STL model
 

Hi everybody,
Can somebody explain what is the best way to create a solid part from an STL file like the picture in SpaceClaim?

Thanks in advance

An STL file is a set of triangles that usually forms the boundary of a solid (the format doesn't require it). So it is typically a solid part albeit often a low quality one in comparison with other formats due to approximating curved surfaces with flat triangles.

By solid part do you mean the particular form of solid model adopted by a particular CAD package? Or perhaps the NURBS BRep model of an IGES or STEP file?

Hi Andy,
Thanks for answering,
If you use SpceClaim, you have seen the differenece between a real solid and a facetted body. Just converting a SLT part generates a lot of facettes and the model becomes very heavy. I succeded to make a solid of the part, but with a lot of work, using multiple profiles and joining them together.
The target is to have the ability to modify the part, what is not possible on the STL.
Best regards

I have no knowledge of how to drive SpaceClaim or it's capabilities.

I did once have to work with a 3D geometry in an STL file because the client's license had expired and this was all they could find. A large number of triangles wasn't an issue because my grid generator could move grid points across triangle boundaries during smoothing. However, what was a problem was that many of the sharp edges between surfaces had not been preserved. That is, whatever generated the triangles initially didn't align triangle edges with geometry edges. This was in the 90s when several of the leading CAD packages were poor at this sort of thing. Recovering the edges involved fitting the triangle vertices away from the edges to a NURBS surface and generating a NURBS BRep solid model. This took an afternoon or two because I had code for an internal NURBS based BRep solid modeller. Without it I would probably have had to reverse engineer the proprietary binary file of the commercial software to extract the NURBS surfaces and patches which the client still possessed but could do nothing with without shelling out large sums for another license.

It looks like you may have performed a similar task to me but using a commercial package rather than coding.

For SpaceClaim, for an imported iges or stl component that is just a transparent surface or a mesh: 1) select the part in the structure tree or box select the component (it will be highlighted), 2) Select the 'Repair' Menu Tab, 3) all the following tools are in the 'Solidify' Tool Group, 4) first click 'Missing Faces' tool - if none found or if some problems are highlighted, click the green checkmark box to fix or finish, 5) then click 'Gaps' tool - if none found or if some problems are highlighted, click the green checkmark box to fix or finish. When repair is made, the image will convert immediately to a solid -- in the Structure Tree, the designation of the component will change from 'Surface' to 'Solid'. 6) If component is known to have no gaps or face issues, can just click on the 'Stitch' tool to immediately enclose surfaces and change to a solid. Using SpaceClaim 2021R1, but this is applicable to several recent revs. Very fast, <1 sec for a >5MB model.