Yeah, use of printed shims, a flat washer, a shoulder washer, and my multiple layers of kapton tape have all been ways people have improved the fit of the hexagon hot end in the greg's wade extruder.

FWIW, in my cut at refining the wade's extruder (http://www.thingiverse.com/thing:812899), I added a definition for the hexagon to the other hot end types already in the legacy openSCAD file. That makes it pretty easy to customize the diameter and depth of the large hole for the hot end - I felt that's a better solution than just shimming it until it fits. I also added a customized u-channel plate that will print to the same dimensions as the greg's wade body. No more fretting over which is the top and bottom of the U-channel plate, and no more overhang.