Dean,

If you prefer to machine from solid and dont mind the wastage feel free I went for the lowest cost approach.

When you say 'shaft sticking out' I assume you mean the inner end of the axle? Thats why there are 2 spacers, the second goes on the end of the axle and a standard M8 nyloc nut & washer bears against it. I did it this way as in the past i found a M8 nut is too large and fouls the bearing outer race (da max for bearing 12mm, A/C for nut is 15mm) and turning an M8 washer down to 12mm is fiddly.

But if you have a better solution....