One point of discussion arises from time to time when someone says: “I model in H0 Gauge”. It is potentially confusing because people sometimes confuse the terms Scale and Gauge. Granted, this is a minor issue in the greater scheme of things, but if you’re going to be accurate, it is helpful to distinguish between these two terms.
Scale refers to the proportion of the trains, structures and vehicles, regardless of the track gauge upon which these trains operate. Gauge refers to the distance between the rails. In H0, it is possible to model trains in several different gauges, both Standard Gauge (4’ 81/2”, or 56 1/2”, in much of the civilized world) and the various narrow gauges. In the case of H0, common narrow gauges include 3 foot gauge (H0n3), 30” gauge (the popular H0n30) or two foot gauge (H0n2). Just to confuse the issue a bit more, there are several ways to describe H0n30; you will often encounter H0n21/2 and H0e. In all these cases, H0n30 trains are still modeled to a scale of 1:87. This means that the locomotives and cars are 1 inch long models of 87 inches on the real thing. In most cases, narrow gauge trains are smaller in the real world as they are in the model world, but they still are built to one scale proportion.
In the case of H0n30, the trains operate on a track whose gauge is 30” between the rails, narrow gauge. They are also built in a scale proportion of 1:87. Conveniently, the 30”€¯ gauged track is close to 9 mm in H0-Scale. 9 mm track gauge is also used in N-Scale to represent standard gauge track of 4’ 8 1/2”.
H0n30 became popular through the work of Dave Frary & Bob Hayden, who produced a series of magazine articles called “Thatcher‘s Inlet” in the early 1970’s, creating an H0-Scale model railroad operating on the H0n30 track gauge gauge. A manufacturer had created a series of appealing H0-Scale models that utilized N-Scale track which were also inexpensive. Further development of the scale was enabled by the supply of N-Scale locomotive mechanisms, wheels and track. Later, several manufacturers would produce items for H0n30, but the initial work was already done. So, too, 0n30 uses H0 gauged track to represent 30” track gauge. And, in the same way, Nn3 uses Z-Scale track.