Hi Michael, I assumed too much...



so in this image I can successfully boolean diff the blue object from the magenta base object ( trim works equally well ) resulting in...



but when I try the same thing with cyan curve ( either boolean or trim ) it doesn't work. I've tried recreating ensuring symmetry so I'm not sure what I'm doing wrong...



lastly, I notice that viewing from the right results in same image as viewing from the left, but should I see cyan and not magenta line from the right ?

right view


left view

I hope the next model help you

Hi Sven, ok thanks I think I understand better now.

Surfaces that barely graze each other and are also tangent can tend to be more difficult in surface/surface intersection calculations.

It will be easier for Trim to work on your cyan plane if you select the edges as the cutting objects rather than the full object, like this:



Then it should be cut up ok:



Also another way you can do it is to draw in 2 connecting lines like this:


Then select the lines and edges like this:



And then Construct > Planar can make a trimmed plane there:



- Michael

Thanks for explanation Michael. I realize that there are other solutions, just figured I had to be doing something wrong given the symmetry of model and it working one side, but not the other.

Thanks for the models vic.

Sven