I'm fairly sure....that the knurled nut is knurled for hand gripping.When I do up stearing head bearings I know it is a ballance between not enough and too much.With clean undamaged threads,I use several hand gripping tightening and loosening cycles to seat the two bearings and just guess a bit of preload.This is really just a feely thing,in my case,but not too much.Then,I check the play in the forks by pulling them back and forward,listening for any movement in the stearing head.A second pair of hands is usful as you can also use your fingers to sense any movement also but getting good help is often difficult.The lock nut just nips up to prevent any creep of the knurled nut and needs to be tightend without disturbing the knurled nut position....too much.After a hundred miles or so recheck for play in the stearing head and also how freely the stearing swings over.This works for me....