surface generated by sweep helical cut selection problem???

I have modeled a real M12 * 1.75 bolt.
I have created the threads by a sweep helical cut by using
the necessary profile of the thread. There is no problem at all
by sw2003 on modelling a real threaded bolt.

But when it comes to use the model for an analysis by an other
software,
I need to select upper surfaces of the seperate ring like features of
the thread, but sw creates them in such a way that they can only be
selected as a whole surface.
If u look at a threaded bolt, U can easily see that in reality they
are all
independent surfaces ( the upper surfaces of the thread)
Splitting curve on them for splitting is nonsense , in nature they
are splitted, but when it comes to selection , they are a whole.
For try, I splitted a vertical line on them, it splitted the whole
structure wrongly, u can select parts of surface, but when u select 2
of those parts some of on the upper ring while some is on the lower. U
can not select 2nd or 3rd ring as a whole correctly.

How can I overcome that problem???

 

In your thread profile that you are sweeping, remove the tangency
between the fillet at the root of the thread and the flank of the
thread. This should give you a separate surface for the flank

Wayne