I really expected a solid model. It came in as a surface. SolidWorks couldn't heal the surfaces and the gaps. So I had to add some solid geometry. I really need a square drive, not a phillips. I couldn't extrude out the square - likewise because is was a surface - which for some reason - interfered with my geometry.

Stan,

Great work by the way. There was nothing wrong with what you provided. Actually, I think this was a system to system or surface to solids issue. I downloaded and unzipped a whole list of beautifully done step files.

I am working in SolidWorks 2008. I have used step files before, but I can't recall is I could add or subtract from them. I just needed to extrude a solid square drive hole in the head in place of the phillips. I attempted multiple approaches. My final resolution was to use your model for dimensional guidance and created a fresh SW solid in a new file. A more reasonable man might have simply use the screw as is and ignored the drive feature variance.

Thanks again.

My guess is its a limitation in your older release of software. I downloaded these again and tried it in Inventor 2012 and they come in as solids. Maybe check your import options. Do you have a heal or stitch option? Sorry I don't have SolidWorks to test right now.