Hello Michael,
I am stuck again.

I did my ring head as you suggested, with sweep instead of rail revolve.
Indeed that is the way....
However, As I am trying to finish my ring, (see pic), cannot perform the boolean diff to take away the additional part of the head....(see 3dm file).

Now, with rail revolve, I always finished everything (the whole ring) in few clicks...

Why that is happening?

Forgive my ignorance, but thought I had it....

Thank you,
Rudy