Boolean Difference doesn't work

Hello everybody,
Two Boolean Different or Boolean Split functions do not work even though both parts are “closed polysurface” and give the message “Boolean difference failed”
The red piece must be subtracted from the other piece
Please guide me.
Picture and model file of parts:
ttt.3dm (517.5 KB)

There’s a problem with your red object.


ttt_02_tpfix.3dm (4.6 MB)

here is a fast fix.
after fixing the additional surface found by jim - you have to fix the trimming.
see curves on cyan layer fix
(general it would be nice, to be modelled precisely from the beginning…)
so this is a fast and dirty fix.

after this fix boolean-Difference works but resulting in an non-manifold polysurface at (x)

this is caused by a very sharp angled surface…
I used _mergeSrf and _removeAllNakedMicroedges in the initial red cutting surfaces

hope the result helps - otherwise I recommend to rework the initial surfaces. for example those 2 surfaces should be a single one:

same here:
(the left part, is the one i fast-fixed with _mergeSrf)

hope this helps - kind regards -tom


Thank you so much Jim. Would you please give me how you find the problem.
Thanks a lot

I attempted to manually trim everything and ran into that stray surface.

1 Like

Dear Tom, I really appreciate your guidance and correcting the problems.
I tried to redesign with your advice, but the same problem exists in the red object. The red object is actually a cutter for the ear, which should be created with a slightly larger size than the head piece so that the two pieces fit together well after printing.
I created the red piece by separating the outer surface from the head and merging the surfaces and offset, but it is not correct.
ttt_03.3dm (2.2 MB)
Best regards, Pouria

you improved the surfaces, but you did not get rid of this inner surfaces - which form a overlap.
(see also jim s post, first answer)

Thanks a lot :pray:

Thanks a lot Tom :pray: