Hi Olle, just to help clarify, the particular problem looks like an area of "self intersection" near the bottom of the blades. That's where some surfaces of the object criss-cross back over each other, that kind of formation will prevent a solid from having a proper consistent inside and outside region and that can interfere with booleans and intersection calculations.

Here's the area in particular, notice the kind of curly-cue crossing loop:





- Michael

Thanks for explaining. The blades were created with a sweep (flat) and a helix (that was scaled 1D a little bit) as rail.

Hello,

You could also try creating the curve framework using a copy of the rectangle, Helix command, Network each face, Join, then Planar to cap the ends. It results in a better cutting surface with less end ripple. The original is in grey, the Networked in orange.

Hello,

You can further reduce the ripple by rebuilding the construction curves with something like a tolerance of .001 prior to performing the Network command. The original is grey, Networked solid is orange, and the green solid had the Rebuild command run against the curves prior to the Network command.

Thanks to all of You, helped me a lot.