Why does Boolean Difference fail here?

not sure boolean difference is failing here.

red block is the cutter.

see attached
BooleanDifference fail.3dm (1.0 MB)


Hi @Steve1

Your part (not the cutter) has lots of naked edges. Rhino can’t boolean through the naked areas, as there is nothing there to cut. Fix it or use split instead (remember to ungroup before or after splitting, so that you can actually delete the split parts).

HTH, Jakob

Thanks, after splitting its a bit of a dogs breakfast to seal up so I will simplify it and hollow cylinder it and boolean that instead.