Is Attached what you want to achive ?
I did exlode your Acis so i could get the "circle" to follow, made a 3 pont circle and trim it, guess i could have used a 3 point arc aswell, moved the arc to M on the triangle and sweep work like a charm when i use the arc as a path.
You can use section tool also to get the profile, but i dont need the rest of the solid so …
Red is Path, Blue is membrane
V20, V21, 2015/ 16/ 17/ 18/ 19 Pro. Platinum
Deluxe 2015/ 16/ 19
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