Scale and gauge, and the art of compromise

Having set out my love of the quirky side of railways, perhaps I should explain something about my approach to scale and gauge, and to the differences I apply to what may be considered the ‘mainstream’ modelling scales.

Scale, in its strictest definition, is the ratio between the full size and the model, e.g. 1/100, 1/76, 1/87 and so on.

Gauge is the distance between the rails, which obviously has to be identical over the whole railway, otherwise the trains would fall off. British standard gauge is 4′ 8 1/2 “.

Narrow gauge is basically anything less than 4′ 8 1/2″, which can be from 18 inches up to about 4 feet.

If you apply the scale to the prototype gauge, you would expect the model to be an exact reduction, wouldn’t you? Yes, well, this is where it starts to get complicated. While you can scale down length, width & height, some things when scaled down are simply too fine to work in model railways, like wheel flanges and valve gear for instance.

Add in manufacturing tolerances applicable at the birth of small scale models in the 1920’s, and certain compromises had to be made in order for the model trains to function, some of which we are still living with today.

There have been enough electrons disturbed on how and why we have ended up with the current mish mash of British scales and gauges, and I don’t intend to repeat them here. If you are interested, look up Henry Greenly and A R Walkley, and their involvement in the early development of this hobby.

In the next post I shall discuss some examples of the compromises used by manufacturers, and how we can turn those to our advantage.