Prusa Y rail alignment tool

Although I designed this tool to align the Y rods on my Prusa MK2 Bear modification, it can work equally as well on the Original Prusa MK2.

Why do you need this alignment? If the Y rods are not parallel and properly separated, stress will be put on the Y rod bearings which will cause them to loosen and wear prematurely. Also, the stepper motors may lose steps because of the stress. In addition, if the rods are not in alignment with the frame, then the firmware needs to make calculations to compensate, which is not the best way to get things square.

How do you use the Y Alignment Tool (from now on referred to as ‘YAT’)?

First, attach your front left corner Y rod mount in the position suggested by Prusa or the Prusa Bear. This will act as the reference point for all other points. The other three Y rod mounts, with rods attached, should be able to more freely.

Second, you snap the YAT onto the top farthest point of the Y rods, just short of the Y rod mounts. Now, you need to s