Hi Mala, here are the construction steps.
Start with a central axis line and 2 circle profiles:
Add angled lines in the Top view:
So initial curve setup should look like this in the 3D view:
Extrude circles:
Trim outer cylinder with this angled cutting line:
Discarding the front half:
Trim inner cylinder with this angled cutting line, discarding back half:
Select these edges and Construct > Loft - and here's a tricky thing since fillet seems to be particularly sensitive to this area in the Loft command I set the option for Profiles : Exact so the generated Loft here goes exactly through those curves and does not have the curves refit like the default mode will do:
Cylinders can be discarded leaving only tapered cone-like piece:
Trim inner circle, use "Add trim points" and snap 2 points onto quad snaps here and discard left half:
Draw in lines:
Select lines and extrude, using "Set dir" option:
Select all 3 pieces, the 2 planes from the extruded lines and also the cone-like surface, and do a "mutual trim". That's where each piece is used as both an object to be cut as well as a cutting object. So start with all 3 pieces selected, run Edit > Trim, at the "Select cutting objects..." prompt just right-click or push "Done" to signal mutual trim mode.
Mutual trim helps improve accuracy because the trimmed result will have completely identical edge curves in their trimming boundaries.
Select these as the pieces to discard:
Select inner semi-circle and extrude it:
Trim by angled cutting line:
Extrude outer circle:
Trim with end angled cutting line, discard back half:
One final trim - trim outer surface with these 2 edges and this angled cutting line:
Select this as the area to discard:
Join surfaces and this should work for filleting:
So one thing that can generally help to increase accuracy is to cut things to common curves. Mutual trim can help too because it will generate an intersection curve which will then directly become part of the trimming boundary of both pieces.
Hope this helps!
- Michael