Got the adapter made and fitted today. It's rock solid.
I got a small M42 helicoid thingy from ebay. Works great for a small load but just won't work for this so decided to go for the primary focuser instead.
Just have to work out how to run a bracket to hold the motor.
I'm thinking of a thin washer sandwiched between the AO and the adapter. Then a belt of some kind.
