Unable to close a hole at a border of shell (imported via stl file )

[Christian_56]

I want to build a solid in Sketchup, but this comes with mistakes and it was no possible to repair withe an in Sketchup. So I try to repair this  structure with Meshmixer.

Frist picture shows the current situation after importing the .stl file. A shell with hole an the border

Frist Attempt : use inspector to show the  mistake, no results, on answer

Situation after importing stl File (sketchup) a shell with a hole at the border

Second attempt:  Select the border and use "fill and erase"... Result: Hole is now closed, but  not in the right location, at the edge to this shell is now  a part of the shell is missing. This is not my aim, see screenshot 

Attempt 1: result after using function fill and erase

Questions: I am looking in serval foreign, but I saw no solution , 

Thanks a lot  for give me a hit, what is wrong  in my operation? My  understanding  this problem with a regular  geometric  form  was by very easy to solve with Meshmixer.

[hfcandrew · Accepted solution]

I think the normals are flipped for those pink triangle.

Select any pink triangle you see > Edit > Flip Normals

[Christian_56 · Accepted solution]

Hi Andrew,

tks a lot of quick answer. Idea is good, but with negative topic:

Due to the circumstances I am not able to select only the pink areas, after using the flip function others are becoming pink

See pictures

Thanks again for helping

christian

[Anonymous · Accepted solution]

Agree with hfcandrew.

The import does not come with an open boundary (no blue line (assuming MM defaults) and the wireframe shows faces and Inspector does not do anything).

So the color on that region might be caused

• either: Its a face group (unlikely)
• or: as hfcandrew said by flipped normals' directions.

To select flipped faces you need to enable AllowBackFaces in the SELECT flyout. Selected backfaces appear black if watched from its back). 

[Christian_56 · Accepted solution]

Hi MagWeb,

thanks a lot , your hint this solving the problem. See the result

Greetings from Würzburg Germany

Christian