Question about x axis frame rails

Ok, I'm assembling the cartesian robot, and I have a question about the x axis. When I attach it to the frame, the little bearing blocks don't touch the rails (they're below the rails); in my setup the x axis rails are resting directly on the upper frame rails. I imagine that will work, but it seems like it'll add some friction and wear as the y axis moves back and forth with a steel on steel slider. Most likely I've just put it together wrong. Can one of you guys with a Darwin let me know - are the steel rails supposed to touch? Thanks!

Wade,

No they Should be metal to metal that is why you need to grease the frame rods.

Do not worry the first time I assembled my machine I thought that the X frame will not work but it will in the end if you follow the instructions.
The main one to be concerned with is the Z axis you need to follow the instructions or else it will bind.

Bruce Wattendorf