Hi Rich,

> One thing that I discovered by trial and error (perhaps it is explained
> elsewhere) is that in using Sweep, the profile cannot be made of
> separate segments. All component segments must first be
> joined for it to function.

Yes - for sweep the profile curve must be a joined curve instead of a bunch of separate individual curves, which is different than Extrude - extrude has an "auto join" mechanism built into it.

The main reason why that is different in Sweep is that Sweep can actually take multiple input curves but it interprets each separate curve as belonging to a different "station" along the path, something like this:



So when you have a bunch of separate unjoined segments for the first profile, Sweep thinks that each one of those separate segments is supposed to be a separate profile at its own station along the rail and will probably make a really jumbled result as it tries to morph from one of those shapes to the other rather than taking the whole set as a single profile at a single station.

I may try to tune up Sweep in the future to do an auto-joining step to glue together touching segments before doing the sweep, but it might actually cause problems if some different stations actually had profiles that happened to touch ends, so I'm not entirely sure about doing that for sweep.

- Michael