As a matter of interest since Fitzroy raised the matter I went and measured the centre section of all the axles. This is supposed to be 40.00mm however since it is a derived length by virtue of the manufacturing process it is the most likely to be variable and wrong. It is also critical since it determines the wheel back to back dimension.
Of the 12,
1 is 39.98
3 are 40.00
1 is 40.02
1 is 40.06
6 are 40.08
which gives a variation of 0.01mm or half a thou, and ignorable. Tick.
Martin