Odd "tailings"

I have some kind of “tailings” in my model like thin surfaces that disappear in wireframe but are there in shaded, ghosted etc. You can’t select them. How do I remove them?

eliptical stair - Copy.3dm (520.3 KB)

SelSrf seems to work for selecting. So does SelBadObjects.

You have surfaces with bad edge definitions. In theory you should be able to use Untrim to get rid of bad edges, but untrim does not seem to work. Not being able to untrim surfaces with bad edges looks like a serious bug to me.

Yeah, those faces have multiple edges piled on top of each other… still digging…
My guess of the moment is that the planes were trimmed from Top by selecting multiple curves that are piled up there in that view. I’ll see if I can reproduce it.

@tortoise - I see the file tolerance is .1 - that is not a good number - too large - in general keep tolerance from .01- .000001. My guess is this is at the root of the problem but so far I cannot reproduce it.