I wasn't a fan of how the original design applied the Z-Axis load to the motor so I made a drop in modified IE version of the F-Z-Lower which incorporates a thrust plate. The design also allows for the use of couplings which require an air gap to perform correctly such as the HUCO Oldham Couplings.
x2 608 Bearings (I used Flange versions but regular ones would also work)
x2 M8 Nuts
x2-3 M8 Washers
M4x20 fixings for the conduit mounts
Insert a bearing on either side with enough washers between them to create ~3mm shim, lock the assembly with nut on each end. Finally ensure that there is no air gap between the central bearing shafts (you'll hear washers rattling around if there is).
I have not tried this part under heavy load yet but it functioned nicely under light cuts.