Motor shaft 5mm to 8mm Threaded Rod Coupling (13mm hex nut)

Actually I designed this for my DIY CNC, but since this uses 5mm motor shafts and 8mm threaded rods, like many 3D printers do, maybe someone can use it for his printer.

Put two M8 hex nuts (DIN934) on the rod, seperated by a 8,4mm washer (DIN125) and fasten them tight. The washer fits into the inner notch, hence the threaded rod has no chance to move out of the part.

The parts diameter is smaller in the center on purpose, to provide a little flexibility.