Just to review: on a normal machine the spindle revolves in a clockwise direction, looking down from the top. If the toolpath goes around the outside of the part clockwise, that is climb cutting. If it goes counterclockwise, that is conventional cutting. It sounds like you're having trouble when your machine is trying to cut aluminum in conventional mode. Climb is usually smoother. If you can structure your toolpath so the whole thing is moving in the same direction, rather than changing directions on one side, then your edges will probably look better. Of course, if you're cutting in a slot, the tool is cutting conventionally on one side and in climb mode on the other, which can rock the tool around, dull it, and cause rough edges. If that's your problem, then cutting the thing out roughly at first, leaving some margin for a continuous climb-only finishing cut at the end, might be your best solution.