Hi Don, so that would seem to explain it - if TurboCAD encounters a STEP file that contains a set of joined surfaces that do not form a fully closed solid, it seems to explode them into individual surfaces.

So some of the tips in this other recent thread on generating STLs may be useful - there is an indicator in the object properties panel that will tell you whether a selected object is a fully closed solid or not:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3897.8


Does TurboCAD not really have the concept in it of joined surfaces that do not form a solid? Does it have anything like a "Join" or "Stitch" or "Sew" type command that lets you glue together surfaces at their shared edges into connected pieces?

- Michael