S Scale

Frequently Asked Questions

Sponsored by
B.T.S.

As you can see, we are big advocates of S scale modeling. As with any specialized hobby, we have select terms and phrases that are extremely confusing to those just joining our group. Hopefully, the following will help.

1. What is 'S' Scale?

In the purest sense of the term, it is a modeling ratio that can be referenced in several ways:

  • 1:64
  • 1/64th
  • 64 scale feet per actual foot
  • 3/16" (0.1875") equals one scale foot

When looking at other model trains, just remember...
'S' is bigger than HO (1/87) and smaller than O (1/48).

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2. What is S Gauge?

 Gauge refers to the distance between the rails. In real life, most U.S. trains use Standard Gauge which is 4'-8.5" between the rails. S standard gauge works out to be 0.883" between the rails.

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3. What does the 'n3' mean in the term 'Sn3'?

 The small 'n' is used to denote Narrow Gauge. The number following the 'n' denotes the distance between the rails, usually in feet or meters. In many places in the world, the distance between the rails is less than the U.S. 4'-8.5" standard.

For example, in Colorado there are two rail lines left from the old D&RGW narrow gauge line. These use track that is gauged at 36" between the rails. Modeling this in S scale is referred to as Sn3. In Maine, two-foot gauge was used around the cranberry bogs; this is Sn2.

If you see a large number, such as Sn42, that is not 42 feet, but 42 inches. It is less cumbersome to use this nomenclature than Sn3'-6" or Sn3-1/2, but over the years, you will see it listed every way possible.

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4. So, is S a gauge or a scale?

 Yes! S is both a track gauge and a modeling scale. Regretfully, the two are intermixed in average conversation, so it is important to listen carefully to the use. For example, an 'S scale modeler' may or may not be using S gauge; the modeler may be a narrow gauge modeler using Sn3 track. But a modeler building an S gauge train layout will use S scale as a modeling ratio. Clear as mud, right?

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5. Is American Flyer equipment also S Scale?

 Yes, and no. American Flyer is a line of toy trains from A.C. Gilbert currently owned by Lionel. The equipment, produced during the 1950's, is closer to scale than the Lionel trains; however, many liberties were taken to allow them to negotiate unrealistically-tight curves and handle the abuse of children. Many pieces of American Flyer equipment have been successfully converted to be closer to scale by changing the trucks and other details.

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6. What does the term 'Hi-rail' mean?

 'Hi-rail' is generally used to reference pure American Flyer (AF) and scale hybrids. Many AF-followers prefer the term 'tinplate' when talking about pure Flyer. The hybrids feature well-detailed and accurately-proportioned car and locomotive bodies that have AF-compatible wheels and run on AF-compatible track.

The tall height of the rail (0.125" and taller), needed to clear the large flanges on the AF wheels, created the term 'hi-rail.' When using AF track, a layout can be built quickly and in a smaller area than the scale counterpart.

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7. What is a 'scale' layout? Aren't they all built to the S scale standards?

 'Scale' is one of those multi-use terms that in this use refers to well-detailed and accurately-proportioned car and locomotive bodies that operate on track that is more-closely proportioned to the prototype. While the track is more true to the prototype than 'hi-rail,' it often requires more space and more time to build. The rail height is 0.125" or less, with 0.100", called Code 100, the most common size.

While they all use the same 'modeling scale' of 1/64 where 3/16th inch equals one foot, 'scale' and 'hi-rail' equipment usually cannot be used together on the same track due to tolerances in the wheel and flange size.

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8. Which is better - 'Tinplate' or 'Hi-rail' or 'Scale' - and why?

 It is strictly a personal preference issue - each has its own advantages. Tinplate offers the nostalgia of toys from the 1950's and a chance to remember the fun. Scale provides the opportunity to create museum-quality, realistic models in realistic settings. Hi-rail offers a combination of both.

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9. Some magazines call 'S' the 'scratchbuilder's scale.' Why is that?

 For many years, the S scale modeler needed scratchbuilding skills to have a nice railroad. Few off-the-shelf products existed. Today, and for several years now, that is no longer the case as a growing number of companies provide S scale products.

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10. What couplers are available?

Kadee Quality Products offers the #802 as the S scale coupler. Years ago, S scale modelers were forced to modify an HO #5 by extending the trip pin for use in S. There are still some who prefer this modified coupler to the #802 so you will see them around.

Narrow gauge modelers are lucky as the HO line of couplers works well for S narrow gauge. Kadee #4 and #5 couplers are most often used and many kits have coupler boxes ready for their installation.

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11. What is the minimum radius for S scale?

 Well, that depends. If using small equipment, GP-9's, freight cars, small steam, etc., expect the minimum to be about 28" on the mainline. If running large steam, full-length passenger equipment, etc., plan to use 42" or more as the minimum. Naturally, industrial sidings and parts of the yard may use smaller radii.

Narrow gauge equipment will negotiate even small curves. Many find 22" a nice radius to use. If K-36 or K-37 locomotives are run, look toward using a 28" minimum for better operation and appearance.

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12. Why doesn't my local hobby shop carry S scale products?

 Every business must define their limits, and hobby shops are limited by money available for inventory and space available to display it. Since S scale is a minority scale, it is usually one of the last to be considered as a business opportunity.

Fortunately, several dedicated mail-order dealers have spent the time and money needed to carry a good selection of S scale products.

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13. Why hasn't the NMRA issued a check gauge for S scale?

 For a number of years, the standards approved by the NMRA and those approved by the NASG (National Association of S Gaugers) differed. The NASG offered a check gauge and was trying to convince the NMRA to accept its standards. After a lot of discussion, the NMRA did accept the NASG standards as their own. Since the NASG offered the gauge, it probably seemed the effort to produce a second one was not necessary.

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14. What is the NASG?

 The NASG is the National Association of S Gaugers. Similar to the NMRA, the NASG is a non-profit organization whose mission is to promote model railroading in S. All forms of 1:64 modeling are accepted including Scale, Hi-rail, Tinplate, and Narrow Gauge. A bi-monthly publication, The Dispatch, is included with the membership fee.

The NASG has an annual convention. Check their home page for further info.

It is easy to join the NASG. Simple send $17.00 to:

NASG, Inc. c/o Bill Moore
220 Swedensboro Rd
Gibbstown, NJ 08027-1504

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