When using a custom LogAxis for own label drawing, the value posted by setBase() will be ignored. - Even "double n = axis.calculateLog(2);" works.
That's not a base 2 scaling.
This was a mistake: in a logarithmic scale all multiples have the same distance - independent of the base! Between 1,2,4,8, ... is the same distance, as between 1, 10, 100, 1000, ...