Hi Satoribomb, the central object looks fine.

One area that tends to be difficult to calcualte is stuff involving coincident surfaces - this is when parts of the cutting object runs right along parts of the base object instead of punching through it. For example in this case this area here:



Ideally that wouldn't matter, but it does tend to be an area of complex calculations and sometimes if a boolean is failing you may have to avoid this type of a cut where surfaces are hugging right along each other.

For a workaround in this case, I used Edit/Separate to break your central hub into different surfaces, and then joined just the parts that will actually be cut into their own object, capped it with Construct / Planar, and then booleaned that sub assembly. This worked for all but one of your flanges, one still will not boolean even then.

So I took a closer look at your flange, and it has a kind of messy area in it at one tip:





There is a little tiny extra slivery surface running right along one edge. It is really small - these kinds of little tiny slivers tend to throw a monkey wrench into booleans as well. So that may need to be repaired somehow before the boolean will work completely, maybe just hack off a little bit of the back or something?

Anyway, those 2 issues seem to be what are causing your problems in this case. Let me know if you need any additional help tuning these up.

- Michael