Solid difference, but only for some surfaces

In this example I’m trying to trim one surface with four other.
But only two of them will trim the original surface.

I’ve seen others having a similar problem, but unfortunately not understood the workarounds presented.

All my surfaces are planar.

Any ideas where to start looking?
notches.gh (12.2 KB)

You are working with surfaces, not solids. Might work better if the notches had thickness with unambiguous overlap, but you can use RDiff instead:


notches_2019Oct3a.gh (12.0 KB)

Thank you very much Joseph!

RDiff works perfectly.

Even though my surfaces will eventually be extruded I still choose to work with surfaces since the solid difference works so much faster then.

And with RDiff I can save some more time by using my original polylines instead of surfaces.

I think you are correct that the overlap isn’t unambiguous using surfaces and solid difference.
If I bake all my surfaces and copy-paste them in Moi3D there is no problem using solid difference, so I guess Rhino and Moi3D use different tolerances.

Thanks again, much appreciated.

You can also use trim solid but you need extrude the small surfaces