[NyCityKId]

I may be a little late with this response but how do you keep the part that rotates on the vertical axis (the wheel), firmly attached while allowing it to rotate freely? I'm trying to design a crab drive module of my own and this is the part that I'm stuck on. I know there is a way to do it but I don't really know how. Every way I come up with seems inefficient. Thanks in advance.

-Andre