Problems with sweeps using surface edges

[CNSZU]

Hello everyone,

Is it possible to have a surface sweep run along the edges of a surface made using a spline? The weird thing is that it works with a surface made with an arc.

In this example I'm trying to get a sweep along the edges of a surface made with a spline using the selection manager to select the edges:

http://files.engineering.com/getfil...cc6-7f6d3777f3c5&file=sweep_spline_-_fail.JPG

However, it works fine with an arc:

http://files.engineering.com/getfil...27c-bc9388ef50f5&file=sweep_arc_-_success.JPG

The failed "spline sweep" sw2011 file:

http://files.engineering.com/getfil...75-9eeb-8072f4c2ca6c&file=sweep_spline.SLDPRT

How can I get it to work with the spline?

An additional question: the sweep worked fine using the arc, but why is it not possible to select the option "Twist along path"? SW complains: "to make this option valid, the sweep must have a smooth path". Isn't the surface edge smooth enough?

Are these simply limitations with solidworks? Is there another way to create this geometry?

 

[CNSZU]

OK, I've solved it, for the surface sweep, the start/end tangency type should both be set to "None", and to make a "twist along path", the rule seems to be all path edges need to be tangential to each other. Presumably, that's what is meant by "smooth".