These replace the gantry bearing holders. I got rid of the springs on the belts and went to open loop belting. This gets rid of artifacts resulting from the springs expanding/contracting during acceleration and deceleration. I put bushings in that hold the 6 mm shaft rigid. The 6 mm shafts can not drift because they are secured. The shafts are secured on only one side so that the shafts can shift slightly as the distance between the 8 mm shafts will have some tolerance. Since the 6 mm shafts do not snap in I recommend put one hole in the carriage on each axis to allow the 6 mm rods to slide in an out.
The bushings are inserted. The belts are slightly stretched to slide into the plastic. The cap is then screwed into place with the m2.6 socket head self tapping screws.
The shifter is put on the x axis rod to shift the print head 1.5 mm to the right for clearance.
The result is a much stronger, stiffer assembly giving better prints.
I used ordinary open loop belting which is put in place with a pair of pliers, it is easy to slide in too tight. I found no printing advantage from putting it in tight.
I used m2.6x12mm socket head screws. They should lock the 6mm rods on either side and only one screw per rod so that the rods are able to float back and forth. I used and 8mm x 11mm x 30mm sleeve bearing.