Quote Originally Posted by bartdietrich View Post
The problem is that there is no way to attach the chuck to the motor shaft in a repeatable centred way: the two grub screws allow all sorts of tilted orientations because the motor shaft is thinner than the inside of the chuck. Do you know of any chucks with some kind of reliable attachment systems?

Bart
From this statement it sounds like the problem is the attachment bit of your chuck - to have any chance of good centering the hole that the motor shaft goes into is going to need to be an extremely snug fit. I've had a wee search and like you not had much success with finding an ER11 chuck with a 3mm shaft entry. I did however come across one or two motors with ER11 chuck fitted that look like they might fit your machine on the Bay of fleas for quite reasonable money (£18....25) - might that be a way to go?