Hi Harry. I have just taken approximate measurements off a 1928 scout with drop centres, a 31 scout , and 5 drop centre front wheels. All are slightly different, and vary from flush with the front of the brake plate (1) to 1/4" (1)
The rest are somewhere in between 1/8" and 3/16". My guess is that George intended to have the rear of the brake plate flange approximately in line with the outer edge of the rim, and the tech tip has a line drawn in the wrong place.
Again, my assumption is that the centre of the rim should sit on a plane that bisects the length of the hollow axle, in order to have the rim centred between the rockers when the wheel is installed, so it may help to assemble the bearings and brake plate in the hub to check this out.
Please let me know what you come up with, I will investigate further.
Does anyone else have any definitive info on this ? If we have conflicting info in the manual it would be nice to clarify the situation.