Can someone help me understand why I can't split this object? File Attached

Need to split this object at the spot the cutting plane is positioned, but I can not split it? Tried multiple ways, but can’t seem to figure out why it wont split. Thanks in advance for any help!

wontsplit.3dm (2.2 MB)

Hi Andrew - at the bottom, on the inside of the U-shaped cut, there is a tiny sliver of surface that is .02 units wide - too close to the file tolerance (.01) You could tighten the tolerance to ,001 and it would probably work, but I’d clean up and get rid of the little face - make sure that vertical at the base of the U is all one flat face.

-Pascal

As always, THANK YOU Pascal! Can I ask how you were able to diagnose that? I tried using ALL of the diagnostic tools and none of them came up with any errors.

Hi Andrew- I stumbled on it, really- I noticed the curve of intersection was open there and when I went to extact the surfaces to see what was wrong, there was this extra one. I guess the ‘takeaway’ is that when trimming, splitting. Boolean operations fail, one of the first things to check is the curve(s) of intersection between the objects.

-Pascal