Make X Axis Length Accurate

[gbroques]

The X axis (seen in gray in below screenshot) rests on the Y axis (seen in orange in below screenshot) carriage on the motor side, and on the half carriage idler side.

The latter is a mechanism for auto paralleling of y, such that the X rods go into it and can slide in and out if the Y axes are not parallel. See Y Axis Auto-parallel on OSE wiki for details.

The rods go all the way into both the carriage and half-carriage.

This can be seen in the CAD of the XY gantry from Feb 28, 2020.

Also see Marcin's comment here.