The original axle lengths are in black. Axles of length 3, 5 and 7 now exist.
Bricks, plates, beams and axles of different lengths are needed. Presenting lengths in an arithmetic progression is not very useful. For example, in a hardware store you may find bolts of diameters 2mm, 3mm, 4mm, 5mm, 6mm, ... But using this regular increase has its limits: we would have to produce bolts of 18mm, 19mm, 20mm, 21mm, ... and clearly there is, relatively speaking, not as much difference between the 19mm and 20mm ones than between the 2mm and 3mm ones. Ideally there should be a geometric progression in sizes. The ratio is important, not the absolute difference.
2004-12-01Originally, Lego produced axles only in an arithmetic progression in steps of 2 units: 2, 4, 6, 8, 10, 12.
The original axle lengths are in black. Axles of length 3, 5 and 7 now exist.
If the progression were more geometric, you would expect axle lengths 2, 3, 4, 5, 6, 8 ,10, 12, 16, 20, ... But until recently there were no axles of length 3 or 5 and we still find none longer than 12. For an early model I once had to saw a 6 into two to make two bits of length 3.
The new axles of 3, 5 and 7 are coincidentally in grey plastic.
