I'm starting on my Y Axis and I a question on the location of the bearings.
In the attached pic the bearings are located on the inside of the rods but I have seen designs where the bearings are on the outside. Does it make a difference were the bearings are located?
If the bearings are mounted outside then you can brace between the pipes improving the rigidity and stopping bending distortion in the pipes when tightening the bearings.