So the axle can pass through, a 22mm hole is "milled" in the centre which is slightly wider that the centre of the bearing which has to be free to rotate.
Removed the excess aluminium to make a perfectly round crush plate and then ran the Scotch-Brite wheel over it to remove all scratches.
The disk rotor is bolted back on and the crush plate sits perfectly on the hub. Now for the crush plate on the other side.
