Tried Grinder and Nature...after 5 try, got an 48 hour time...Astro is not a possible outcome of these two...must be the new Steam??!
I've got something breeding with 48 hour time. This was Carrier + Carrier. Dunno.
I can confirm that Grinder + Nature can result in the Steam Bot. After testing approximately 10 times, I got the Steam Bot.
48 hour breed with Grinder Nature - Steam Bot