Hello Michael,
thank you for explanation, now I understand the problem...
I was confused and I focused on spring, while it was also very tricky to get a solid.
The cage was quite simple construction, so I believed the core of the problem is in spring :-)

I like the "clean" constructions avoiding such mess by principle... therefore I have less experience with fixing such problems...
My next challenge is to re-construct the cage to avoid those slivers...

Just one more question:
if i have 1 solid, then i cut it by boolean diff with a single line to get two solids, then I edit both parts, but not connecting faces...And the if i try to join (bool union them again) - it is not possible, moi does nothing, I still have 2 separate solids... what to search for?

Jozef

Hi Jozef,

> it is not possible, moi does nothing, I still have 2 separate solids... what to search for?

Well, I'd probably just take a general look for problems, like self-intersections, slivers, similar to what I looked for in your other case. See if using ShrinkTrimmedSrf gives different behavior or not.

Can you post the 3DM model file (or send it to me at moi@moi3d.com if you want to keep it private) and I'll take a look and see if anything stands out.

If your objects mate up along the cut line, it should be possible to delete the faces along that line and then with 2 pieces that have common open edges select them and use Edit > Join to glue them together rather than boolean union. Join only tries to glue unattached edges to each other, while boolean union also tries to intersect the objects and see if any pieces need to be removed, so it's a much more complex operation than join.

If your edits were right adjacent to the connecting faces with new pieces partially overlapping it may be difficult for the intersector to figure out how to cleanly divide it into separate chunks.

- Michael