Hi Sven, somehow the trimming boundaries on the tapered part have become corrupted, that's why it's not getting displayed properly.

I've attached a repaired version.

- Michael

Thanks for replies. FWIW, I can reproduce at will by starting with the just the attached joined surface and then drawing a cylinder within the surface followed by alternating tapered and regular extrudes.

Sven

Hi Sven, yes it looks like the tapered extrusion surfaces can get pretty dense. If you need to do a sequence of several in a row you may be better off instead putting in circles and then using Construct > Loft > "Loft style = Straight".

- Michael

Actually for this type of thing that is circular around a single axis line it would probably be best to use Revolve.

- Michael