Boolean Difference Issue with Ear Bud Tutorial

Hi guys,

I’m well on my way learning Rhino. I’m completing a helpful tutorial ( and recreating these headphones. At minute 31:15, he makes an array of cylinders and Boolean Subtracts them. I’ve been trying to follow what he is doing and it always turns out that my cylinders join the object I’m trying to subtract them from.

Any idea what it could be? Is it a tolerance thing?

Thanks so much.


Hi Jesai- see Help on troubleshooting Booelans. What you are seeing comes up when objects are not fully closed- if objects are not closed, Rhino has no way to know what you consider to the outside, so it ‘guesses’. To control this, use the Dir command on the inputs to the Boolean and make sure the surface normals are pointing to what you consider to be the outside of the objects (‘Flip’ option on the command line, in Dir)


Hi Pascal,

Thanks for your response. I’m pretty sure that I had all the objects are closed and flipped, but i looks like I overlooked the direction of the bubble.

Thanks so much!

I did a tutorial on this since topic it comes up constantly in my class. Its totally free to view this movie.

Link to Trouble-shooting Solids and Booleans

Thanks so much!