[Stiglr]

I don't think "clean" Booleans exist anywhere, with any program. They're always creating a mess, in my experience, especially if the shape you hope to arrive at is anything near complex (as a gear or bushing obviously is).

Best I've come to expect is that I can, relatively easily, identify groups of vertices I can weld together to produce the clean result.

With what you've got there, might I suggest trying to "trace" vertices to create a poly from a straight-on view of the result, and extrude that poly to get the finished product?