This adapter is specifically to mount the Nimble V2 on the PCB effector that Escher3D is developing with Think3dPrint3d. It uses a hot end mount that is developed by E3D.
Have a look at the effector [here.]
(
https://duet3d.com/wiki/Smart_effector_and_carriage_adapters_for_delta_printer)
In regards to the nut used to mount the hot end to the Smart Effector. There are two sizes of nuts used, unfortunately. 19 mm Across the Flats (AF) and 17 AF. This is the 17 mm one.
Simply bolt the adapter to the hot end mount and bolt the Nimble V2 to the adapter.
This is the fixed model, all bolt holes are now the correct size.
For the Smart effector we developed a part cooling radial fan attachment, one for the 5015 fan, and one for the 4020 fan. Have a look at the first part you will need, the Fan Base. This will guide you to the other parts.