Union of two breps, gives me a problem and breaks down

Hi, I have two breps, with coplanar faces, but when I try to join them, one of them breaks down. what can I do?

image

and then… the edges inside one of the dissapear…

Can you post a Rhino file with the two parts?

It’s difficult to say / guess what’s going wrong without…

Deck.3dm (5.9 MB)
Hi, thanks!!!

Hello - I am not sure I can see what should happen in this situation - what do you expect to happen to the internal tubes at the end where the Union occurs?
Currently, the tubes are capped at the open ends and become independent breps.

image

-Pascal

Hi, what I expect is that the solids stay together, and the tubes stay as one solid inside, but when I put them together, they separate…

This is possible. @Helvetosaur explained how to do this in another toipic I can’t find.

  1. Separate the cylindric parts from the inner three polysurfaces.

  2. boolean Union all main breps.

  3. Remove the tubes on the ends. This results in one large objects and 9 tubes inside are left

  4. select everything and run _NonmanifoldMerge DeleteInput=Yes

Deck.3dm (2.6 MB)

thanks!!! its works!