I decided to make this remix because it is very difficult to align the 4 bearings so that the Y axis slides easily. I have included an extended LM8UU bearing that comes from the IGUS STYLE http://www.thingiverse.com/thing:24990 printed on PLA, and I have adapted the bearing housings to be able to install the 100mm LM8UU. I add the proyect file for Sketchup. You can edit It. Heat bed size for this Y carriage must be 200x200 (most common hotbed)
Print the Y carriage and the bearing housings like your favourite config. I print the Y carriage with a 0.24 layer heigh and a 0.4 nozzle, 40% infill. And the bearing housings the same but 100% infill.
The bearing must be printed with a external perimetral line of 1mm (Slic3r - Print settings - Advanced - External perimeters = 1) and a 0% infill, a layer heigh can be from 0.1 to 0.2. And very important, print slow. Thats my config with a 0.4 nozzle and the size is perfect.
*11/02/17 - Internal part of the LM8UU (100mm) bearing edited so that the contact surface is the same as an original bearing (Less friction). And fixed for be printed without supports or layer fan.