Why cant I fillet/blend my half pipe with its ajoining surfaces?

[Simon_Jackson]

I used a sweep 2 rails to make it, then trimmed the outside and interior.
I removed all the sharp corners to see if that would fix it, and it is a bit better but still not behaving.
This should be a doddle for rhino to do without loads of tedious tweaking, but it is defeating me at every turn.

Any advice would be greatly appreciated, as ive wasted an entire day messing around with this section.
(this model is before I rounded the middle edges, as I cleverly shutdown rhino in frustration)

visor backup.3dm (2.2 MB)

Thank you everyone…this has not been my week.

[Simon_Jackson]

If anyone can suggest an easier way to add detail like this to surfaces I would love to hear it, It doesnt even have to be super accurate.