Scale And Gauge
What does Gauge mean?"Gauge" is all about the distance between the rails. In real, full-size railways, there's a measurement known as "Standard Gauge", which is the standard distance between the rails. Almost all the railways in the country are built to "Standard Gauge", which means that the trains can run on all the railways. There are exceptions to the standard. Where a railway is build with the rails closer together than normal, the term "narrow gauge" is used, and where the rails are futher apart, the term "broad gauge" is used.
Standard gauge track (4' 8¼") and 2 foot narrow
gauge track (under the loco) on the WHR.
© Andy Rutter.
And what does Scale mean?Scale is a term to describe how big a model of something is, for example, a half- scale model is a model which is half the size of the real thing. Scale is measured in a number of ways. Some modelling scales use a ratio. For example, a OO trainset is about 1:76 scale, meaning that one cm on the model equates to 76cm on the real thing. The real thing is about 76 times the size (in linear measurements) of the model. A model of a 6' adult in OO would be about 2.5cm high. Other modelling scales use a comparison, for example "4mm/ft". This tells you that 4mm on the model equates to one foot on the real thing. If you work it out, you'll find that 4mm/ft is 1:76.2. Popular indoor model railways might be one of the following scales.
Name Approx Scales ---- -------------- O 1:32 7mm/ft OO 1:76.2 4mm/ft N 1:148 2mm/ftThese modelling scales are typically used to model standard gauge trains. As such, the rails are 9mm apart for N gauge (hence 'N'), about 18mm apart for OO, and 32mm apart for O Gauge.
Model trains in O scale, OO scale and N scale respectively,
each representing a loco of approximately the same size in real life.
© Andy Watkins.
So what's SM32?OK, this is where it gets a little bit complicated. Modelling in "SM32" generally, means modelling 2ft Narrow Gauge in a scale of 16mm/ft. If you work it out, that means the track is 32mm apart to model 2ft gauge. The "SM" bit refers to 16mm" and the "32" bit refers to 32mm gauge. Got that? The reason for modelling 2ft Narrow Gauge is that a lot of narrow gauge railways are about that gauge. The models are standardised at a particular gauge, even though the prototypes are all slightly different (for example, narrow gauge lines in Wales vary between 1'11½" and 2'6")
And what's G Scale?Here things get even more interesting, because the 'G' refers to a Gauge, and not a scale, which is very naughty of the Garden Railway community, isn't it, calling a Gauge a Scale! The G actually stands for "groß" (gross, the German for "big") but is often believed to mean "Garden". "G scale" basically means a railway where the tracks are 45mm apart, and you can have whatever scale you like (and you can have it indoors if you wish, too). Some commercial scales modelled on 45mm ('G') Gauge track are:
|1:19||2'9"||Accucraft live steam|
|1:20.3||3ft gauge||Accucraft, Bachmann|
|1:29||4'3" ???||Aristocraft live steam|
|1:32||Std Gauge||GAUGE ONE (AKA 3/8" scale)|
on 45mm gauge track, you can have 3ft narrow gauge in approximately 16mm/ft, or you can model standard gauge (it's called "Gauge 1" ) Footnote
 for those of you too young to remember the VHS versus Betamax battle, it was similar to the Blu-Ray vs HD-DVD thing.