I made the profile symetric so I do not have to bother about the orientation. The idea is be build another pipe and both pipe added could make make it.
But I understand I have also to cut the path in two.
For the first profile:
First part : the old path without the straight part. Fine seems to be OK.
Second part: with the straight part of the path only.
The preview while building quite good:
Sorry could somebody agree this function is not stable enough and need some improvement!
I am using FreeCAD very basically, only for CAD, but with complex shapes I agree.
I found many cases where FreeCAD fails (on tangent faces, drags and drops not working, infinite loops, broken structures, and now the pipes, only for those I remind).
I encountered problems in most personal projects I have conducted. To be able to go further, I had to imagine a way not having FreeCAD failing (adding an epsilon here not to have coincident faces, adding and cutting parts instead of directly extruding them, … and sometime just giving up).
I know FreeCAD is also far more than basic CAD. But, as long as the basic stuff is not implemented, does not functioning perfectly in an efficient way, FreeCAD will not take the major place it has the opportunity to take as somehow unique in variety of functions for a CAD system in open world.
In the forum I have been answered quite often, it is not FreeCAD but OpenCascade failing.
The fact is that many cases are really FreeCAD stuff (drags and drop, the colors messed up, the current case), and for the others where OpenCascade fails FreeCAD should take that over, and manage not to have OpenCascade failing, and/or act with OpenCascade team to correct the problems.
A user who decides to use FreeCAD does not bother if OpenCascade has or not been integrated and that the problem comes from OpenCascade. His problem is that FreeCAD as a whole does not work.
I think you should really step back a little and think solving all these glitches, interface with OpenCacade. It does not mean stopping the development of all other functionalities, but put some effort in the core. I spent some hundreds of hours analyzing the code to try to solve the problem of mixing colors, and concluded that some software architecture restructuring is needed, and I have started doing that with some success. But I do not master and understand everything in FreeCAD, I do not have the time for that and there is not much documentation available for that. I missed a committee you should create if not exists, to decide what changes should be made in what order not to break FreeCAD. I request that many times in my post.
And if OpenCascade is really the source of many problems that cannot be worked around or corrected by OpenCascade team, the interface with OpenCascade should be concentrated in specific modules to, at some point, be able to replace it by something else.
It would be a pleasure to participate if you feel I can be of any help.
Here is the file