QIDI rear mounted dual blower for active print cooling

FIRST THING FIRST: this needs a 5mm shim on the Y-axis in order to allow clearance for the blowers and assembly behind the print head. This is critical because when both the build plate is raised all the way up, and the Y-axis is all the way to the rear of the printer, there is no clearance between this blower and Z-axis bearings as the X-axis jogs past.

The Z-axis bearings are wider than the Z-axis rods, so once the Z-axis bearings are lower than the blower assembly, there are no more cleara