Am I missing somnething here???
Mike;
IMHO. I think by sanding the nut or washer allows the nut to travel a greater rotational distance before arriving at the same clamping distance on the spindle. If the nut rotates farther then the castle nut projections/gaps have a better chance of lining up with the hole(s) in the spindle. This technique gives you a bearing pre-load that can eliminate the excess slop. I agree with you, in that one must still allow for expansion that occurs with heat etc. In this case, the OP is dealing with clearances that are excessive with the 1/6 turn technique.
SimS
