[Chadworkz]

Yep, bad idea...you can't let the output shaft ride on the aluminum, even the really hard 7075, that's why you see 99% of the aluminum cups on the market with brass or stainless-steel inserts in the cup. I mean, you can use the 7075 as a wear surface, but it won't take long for slop to develop on that side.

7075 is an awesome choice to make the cup out of, as long as you add a brass or stainless-steel insert for the output shaft to ride on. You don't have to worry about the output shaft on the ring-gear side, because the ring-gear is hardened-steel and makes an excellent wear surface.

The Ti cross-pin idea sounds fine, even though they will have spider gears rotating on them, but the spider gears themselves are soft enough for it not to matter.

I think you have a great idea!

yes, I always cross-pattern tighten.