Hi Koi, just as some additional explanation on why boolean union wasn't working for you - if you have a solid with "wall thickness" like this:



then it's not going to work to try and insert just one open surface across the top of it:



that won't make a volume because there would be no thickness in that top area. Instead of just one surface draped over the top if you formed an entire solid plug to boolean union in that could work but for restoring cut away areas it can be better to do "untrim" instead, there is some more info on untrim here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=444.4
http://moi3d.com/forum/index.php?webtag=MOI&msg=9671.5

- Michael

Hi Michael,

thank you so much! Your support is great, I take you as an example!

Now I definitely understand, thanks for the links to the older posts.
Sorry for my bad english by the way..

I got one more question, I will send you the data.

I want to build a rim for a bicycle. I made the rim and now I want to add little rings for the spokes. These are all solids but I can´t b. union them together.
Can you tell me why?

And second: A friend told me, sometimes it works when you start the program again. He does it sometimes with b. union problems with rhino.
With another little problem it worked with Moi3D as well. But this time not...

Michael, thank you so much and have a great day!

Koi

hi Koi, it's probably because the pieces are not quite fully aligned with each other, there is a sort of really thin slivery "shelf" like shape that would need to be created by the boolean. Things involving skinny fragments like this can make things difficult for the boolean intersection calculations:





I'll take a look at it some more later to see if I can give you any suggestions.

- Michael

Probably the best bet would be to scale the ring pieces slightly up or down so that they will have a simpler and cleaner intersection with the main piece without any sliver thin pieces getting created.

- Michael

Hi Koi, here's a version with those pieces booleaned in now. I scaled the rings slightly so they had a better intersection with the surrounding geometry.

3DM file attached.

- Michael

Hey Michael,
I understand... Thank you so much!! Also for sending me the right object :)

Thank you again and have a nice day!

Koi