Improved y-axis carriage attachment for prusa i3

Too much slack due to high tolerance in smooth rods and linear bearings led my Prusa i3 to noise at any speed and to the build up of ressonance in the y-axis belt even at moderate 40mm/s printing or moving speeds. This ressonance eventually led to the belt slipping off from its pulley.

The actual rods provided by Replikeo in my kit was far from smooth and buying low tolerance rods and bearings was too expensive. I even bought some cheap high tolerance bearings in the hope that the original we