Rotating irregular shape 180 degrees

[MLUY]

Ok, Hello everybody here at Sketchcity this is my first post...completely a freshfish
I Have been looking around on this site for a while after discovering Sketchup a few weeks ago.
Again its deep in the night but still not managed to solve my problem...and about to give up

I am trying to rotate a simple shape (exact) 180 degrees to get a special type of cone-shape (or "round head" for use in civil engineering application, rock breakwater) By using the follow me tool I thought that should be straightforward...but its not

See attached, why doesn't sketchup complete the exact amount degrees I am telling it to do:
From Step 3 you can see the angle is not exact 180 degrees. It supposed to be dead straight (as the circle is exactly 180 deg) I did notice that it helps a bit if I increase my circle segments but more than 150 does not matter any more

Who can explain what the heck is going on?

Thanks

Michiel

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[Box]

The profile for follow me needs to be perpendicular to the end segments of the path.
If you use a full circle then remove half it will work.

By the way, Please use meaningful thread titles.

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[S Shepherd]

If your roundhead is just an end to a breakwater, you could try something like this:

Shep

[cotty]

Another example for Box answer:

[MLUY]

What a simple solution!
Thanks very much for your lightning fast response, sometimes you can stare yourself blind.
Ehh...I have some more problems, but because I could not even solve the simplest puzzle I left those.
So...some new challenges ahead, but no more mightnight oil burning for me.
With help through this forum I should be able to prevent that
Thanks again!!