I am putting together the Z-Axis ball screw for my HF 12 sp mill. Based on some of the great designs on this forum, I am going to turn the ball nut to raise & lower the z-axis. I have the design basically figured out. I am missing a few things. Maybe someone can help.

When mouting the ball screw between the top & bottom plate, a bearing of some sort is required. Will a ball bearing thrust washer surfice? I am concerned this provides no lateral support. Should I use a tappered bearing in this area to insure the assembly stays centered? If so, how do I mount up the bearing? What specific bearing will work for this?

Thanks in advance.