Boolean difference not working with imported iges in Rhino for Mac


Hello all,
Im working with the latest update in Rhino for Mac 5.4.1 and Im trying to create screw holes in a product
that Im designing. I’ve imported a screw from McMaster Carr in the IGES format. When I try to use the screw in the surface that I’ve created to perform a Boolean difference thus leaving just the threads of the screw, nothing happens? I thought it might be that particular bolt but have downloaded several and get the same results. Is there a better format to download than the IGES for this procedure?Odd bolt.3dm (3.8 MB)

(Wim Dekeyser) #2

When having problems with booleans, always check the intersection between the object. In this case, you will find 175 intersections where you should only have 2. If you ungroup the screw surfaces and join them instead, the operation is more likely to work.

Note that, in this position, you won’t be able to insert the screw into the plate as a section of the hole is not threaded. Make a copy of the screw, pull it out some, use trim, split, and join to make the plate with hole.


Thanks for the info wim! I’ll give it a try!




Joining! That did the trick!

Thanks again,



Well I thought the problem was solved? However, if someone is kind enough to look at this file, you will see that there are two bolts downloaded from Mcmaster Carr. One of the bolts works fine as a boolean difference, the other makes the object to be subtracted from disappear? Thanks in advance for any help!Odd bolt.3dm (7.1 MB)

(Pascal Golay) #6

Hi Rick - for some reason the file is not available here at the moment but most likely, one of the objects is not fully closed and has its normals pointing inward - use the Dir (Analyze menu > Direction) command and the Flip option to make sure all objects have their normals pointing to what you consider to be the ‘outside’ (Rhino cannot tell on open objects)



That did it! You are incredible Pascal!

Thanks again,