UPDATE 3/17/2017 - I have updated both carriers the x tensioner and the x motor carrier to eliminate any binding on the x axis when using IGUS bearings mainly by correcting the spacing of the x rods on the carriers. I have included both upgraded carriers now the tensioner and the x motor carrier for the Original Prusa i3 MK2.
This is a X Idler/Belt Tentioner for the Original Prusa MK2 Printer. With this setup you can easily remove the x smooth rods of you need to without having to take apart your printer. Remove the tensioner screw and brace and slide out the rods. The x tensioner has built in manual supports that you will remove after printing.
You will need two M3 screws for the brace which out the pressure on the rods and not bend anything when tension is applied and an M4 and hex head bolt and nut. The bolt needs to be about 40mm and you can cut it to your size if need be if it's too long. The hex head screw goes into the pulley arm and through the idler and secure with the tensioner round screw that will have the nut placed inside of it in the space provided.