Boolean Operations not working between two polysurfaces

Hi all,

I’m very new to Rhino, and I am trying to do a BooleanSplit between two polysurfaces. Basically I want to create a fillet but since the angle is a bit steep and curved, I will have to do a BooleanSplit instead of Fillet.

I created a Loft polysurface using the top edge of the object. Then I moved the polysurface so that it is intersecting with the object, and then I did the BooleanSplit. It failed, unfortunately, and other Boolean operations didn’t go through either. I checked the intersection using the Intersect command and it gave me a ‘closed curve’, so doesn’t that mean both objects are intersecting?

Any help would be appreciated. Thanks a lot!

hanger.3dm (410.6 KB)

I don’t know why a boolean fails on this one.
Personally, I wouldn’t have thought about using a boolean here - just use the trim command and join.

Hi Ed - It does look like it ought to work - I’ll see if I can figure out what’s gone amiss… OK - several … most… of the surfaces in the open object have stacked control points. My guess is that is the problem. Were the input curves for this object made in Rhino?


Hi Pascal, thanks for the response. I made the vector lines on Inkscape. I saved it as a PDF and then imported it in Rhino. Is that what you meant by input curves?

Yep - 2d print/web/graphics programs do not always make curves that are suitable for surfacing … as in this case. Usually there are imprecisions in continuity and loopy curves, and occasionally stacked points like this. Rhino allows them but does not like them much.
BTW, I lied - the stacked points are at one end of these curves, not both.


Hi Wim,

I used the trim command but instead it kept the polysurface that was meant to be cut. I tried using BooleanDifference on the model using the resulting trimmed surface, but the resulting trim was an open polysurface, so there wasn’t any intersection. Hope that makes sense.

Is there a way to keep the original model after trimming just like a Boolean operation? I through it had something to do with the normals but even after I flip the normals of the trimming surface nothing changed.

What’s the best way to go about making this model? Do I need to redraw the curves on Rhino?

I had an earlier version which I was successful with using the BooleanSplit. The curves were made in Inkscape too. Actually the input curves were originally made in Illustrator by someone else and I had it converted into PDF. Not sure if that adds to the problem.

No, not if you ask me. (and perhaps depending on what you will do with this later on in the work flow)
Just use the trim command and make sure you click on the correct side of the objects:




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Hi Wim,

Thanks! I selected the wrong side earlier. Do I use the Join command on the trimmed model and the cutting surface to close that gap? I was unable to do that.

Well, you’ll need to trim the cutting surface with the trimmed one as well.

Ah, gotcha. That works like a charm. Thanks a lot for your help.

Hey Pascal, I tried using the intersection curve to trim the two objects but that didn’t work either. I guess there’s something more going on than stacked points on one end…

Yeah - I think the stacked points are at least part of the problem (they are in the curve of intersection as well) but I’m poking at it some more - splitting works OK per surface but not for the polysurface.