Solid Difference

Dear All

I am doing two similar SDiff operations where one is doing well, but the other is not doing as I wish. Can anyone please help and spot the mistanke?

Kind regards

The grasshopper files is attached:

Question (804.0 KB)

This is almost a “common” problem in rhino too, not just grasshopper.
You have a lot of common/coincident edges between A and B, and you have also coincident surfaces, you should avoid doing that.

As in your case, sometime it works, sometime not (especially with curved nurbs), it’s not a reliable method.

You should make geometries that fully intersect, not that just “touch” in some point.

The same logic apply in the length of the breps, make the “B” slight longer than A.