Got my Nylon 618 and printed some gears for a test with good results. Printed at 245° C with an unheated build plate. My build plate is a glass plate coated with Elmer's purple glue sticks (rkopf-worked like a charm). I did find that even using an unheated build plate that I was getting some curling/rounding of my gear on the bottom. I solved that by using a raft. At first, I thought using a raft with Nylon might be difficult to separate but it was easy as pie. Also no difficulty popping off my build after the glass plate cooled. I think I'm now off and running with printing Nylon.