I'm trying to create curves as illustrated by the red lines in the attached image. I have tried selecting the top curve, boolean>union, the circle curve and then the done button. But nothing happens. I've tried every boolean option in every order of selecting curves that I can think of but I can't get it to produce the resulting curve (in red) that I'm hoping for. Any ideas what I might be doing wrong or how to accomplish this? Thanks.

Are you sure all the curves are coplanar? Look in a different window to make sure. If even one is not on the same plane then it won't work.

Geoff, please post .3dm

I'd try trim, but am unsure of your 3d geometry.

- Brian

Sure, here you go. I'm not sure if the background image will cause a problem if it's not found, so I'm attaching that too. Thanks!

@chipp, they are all on the same axis, but not necessarily on the same plane (z-position). Do they need to be?

Using the trim command worked great. But now I'm left with open curves and I'm guessing because they're not on the same plane, that's why they won't join. How do you reposition a curve so it's on the same plane as others? thanks.

Nevermind, I figured out how to get them to the same position and after doing that they joined properly. So, thanks everyone for the help!

Hi geoff, I'm glad you got it figured out!

Yes for curve/curve booleans the different curves involved need to be all one the same plane.

Trim on the other hand can deal with "apparent intersections" and can cut things that are on different planes from one another, but you will still need to move them to a common plane in order to join them into one piece after that.

- Michael