Boolean Intersect Fails without an error message

In the attached file I have a circular bracket that I need to cut a scallop edge. (I know you folks don’t like my large scallops). I used FLOW to bend a linear scallop into a circular one.

Problem Boolean Intersect.3dm (5.8 MB)

If I try extruding and boolean intersecting, Rhino takes a long time but does nothing. There is no error message.

[Problem Boolean Intersect.3dm|attachment]


  1. Why does Rhino just not do it?
  2. Is there a more effective way to do this?

It is for a book illustration and this is a key feature of the illustration.

(I realized I had uploaded an olde version of the file. Trying so many things creates so many versions and photo mismatches)

The test for booleans working or not is the intersect command, intersect your two objects and look at the curve… is it broken, or not closed? that is why the boolean failed.

I can’t even get an intersection. Had one running over night. Turns out it does the same thing. No intersection and no error.

UPDATE: Shiver me timbers. I kept doing the same thing over and over and eventually it did intersect. Einstein was wrong.

Is there a better way to approach this problem that does not tax rhino so much?

The next one I need to needs the scallop to go radially which is likely to be a bigger problem.

FWIW: Someone in the 1940’s thought it would be better to avoid welding plates together directly. He thought it would be better to put a plate over the joint, machine the plate to have a curvy edge, then weld the curvy wedge plate over the joint. The curvy edge would give greater welding surface than a straight edge. It was probably as much of a PITA to do in in steel as it is in Rhino.