Boolean add problem -- how to troubleshoot

Boolean add fails. Subject is a 19th century naval cannon, and the problem is to unit the breech block housing with the barrel. The barrel is formed with a “revolve.” It is designed to intrude slightly on the structure of the breech housing, in the hope a boolean union. No luck. How would I troubleshoot this problem? Using Rhino 5.0 Thank you for your insights. boolean add problem.3dm (447.2 KB)

Hello - the BooleanUnion here, if it worked, would eliminate the two faces that are at the intersection. So, the way to do this is to remove those faces and then simply Join the two parts. This fails because the edges are close but not quite within tolerance, between the two pieces

Really, as far as I can see, the simple thing is to draw clean curves - many are alaready in place -and make a clean new Revolved object from here on out:


Many thanks Pascal, that solved it. A simple merge. Was not able to use MatchSrf first, but it merged successfully anyway. All best, Michael