Surfaces are not solids. STL is a solid file format, though unsuitable for much of anything except direct use in a rapid prototyping machine. For exporting to dumb solids you would be much better off saving the file in Parasolid or ACIS formats, especially if sending it to an RP house.
As for getting your surfaces to a solid file you will will need to knit/close the surfaces and tell SWX to make it into a solid body, then you can save it out as a dumb solid.
Updraft,
Thank you for taking the time to reply. I am well aware of the difference between a solid model and a surface model. However, for what I need to do I must have an STL file with open geometry, think of a cup where the cylinder and the bottom are just surfaces i.e. zero thickness. It can be done, we have a file. I just don't know how it was done. I need to create updated versions and the guy that did the 1st one is no longer here.
I just made a simple open box out of surfaces and then selected Save As -> STL and created a file. I then opened that file in SWX to verify that it worked. I don't do much with surfaces so that explains the perspective in my first reply, but, due to your challenge, I learned something new today.
As to your original question - have you tried Save As -> STL? It just worked for me.
StrykerTECH:
Solidworks will only take dimensions .00000394in (0.1micron) and larger. I did try using a very small thickness and it still creates seperate surfaces for the inside and outside of the cylinder. This causes problems with software that this is imported into.
Kevin:
I have tried knitting the surfaces, the same error. I don't think solidworks can do what I want and as I have learned more about STL files I understand why. An STL file is simply a list of triangles with the xyz coordinates of the corners and an xyz normal vector which designates which side of the surface was external to the model and which side was internal(solid). When a model has no thickness, the software cannot know which direction to assign to the normal vector.
Yeah, you're probably right it needs thickness, better worded it needs to have a closed and defined surface area when slices are made to build the layers of the object for printing.
