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Part 3 - S Modular Railroading

The S-Mod System of Module Railroading

By Don Thompson and Don DeWitt

Part 3

Reprints from "The Herald" by permission of author.

Adapted for the WWW by Paul Yorke

The last installment in this series dealt with benchwork. We saw how the sections of this module could be made to NASG Standards, thereby making them compatible with hundreds of units already in existence. This time we are going to lay ties, place turnouts and install rail. The work is not difficult and only simple tools are required. Variations in rail height for all scale or mixed scale/hi-rail operation are discussed. To assist the modeler in getting started, a list of manufacturers and dealers follows this chapter.
Before we start, we have to decide which rail size and type of turnout will be used and to what standards the track will be laid. The rail size and turnout type depend on the type of equipment you are planning to operate. If you (or your club) plan to operate both scale and hi-rail rolling stock, then code 125 rail is the minimum required, as are closed frog turnouts.

Gargraves trackage is suitable for tinplate operation; however, it is not the purpose of this series to build modules solely for that use. This topic is covered in the series on the Easyville Shortline RR and details for laying this product will be discussed in installments under that title.

Modules that are for use with scale model equipment are generally laid with code 100 rail. Flexible track is available from Tomalco and open frog switches from American Models, Darr and Earl Eshelman. Hi-rail and AF equipment will not operate on this rail due to their increased flange depth. Their wheels will foul at switches and bump along on the tops of the ties.

The standards used for track gauge may seem confusing at first, as two are recognized for S scale. The first is from the NMRA, which defines its rail spacing as a percentage of the O scale gauge. The second is from the NASG and is derived from the actual 56 1/2" prototype gauge. This confusion tends to evaporate, however, when one attempts to obtain the NMRA check gage and learns that it has been unavailable since the mid-seventies. The NASG check gage is available from the Association's Clearing House and, as almost all commercially available track and equipment is manufactured to this standard, this is the correct check gage to use.

Let's get started laying track!

The first step is to mark the roadbed where the track components will be located. This will be easier if all the sections are clamped together. If we look at the track plan (Fig. 1a Fig. 1b), we find the centerline between the two mainline tracks is 15" from the near edge of the module. This reference line runs the length of the three sections of the module. The simplest way to mark it is to snap a chalk line.

The center-to-center distance between the two mainline tracks is 2 3/4". (This is the NASG standard.) In order to construct the lines along which the edges of the ties will be located, you will have to know the length of your ties. Tomalco uses scale 8' (1 1/2") ties. Prototype ties are usually 8' 6" or 9' and may be encountered in hand laid trackwork. If you are using flex track (8' ties), snap a line 2 7/8" (1/2 the center-to-center distance, plus 1/2 the tie length) on each side of the centerline. For 8' 6" ties, these lines will be 2 11/64"from the centerline, and for 9' ties they will be 2 7/32" from center. 

There are eleven turnouts on this module (3-#8, 6-#6, 1-#5, and 1-#4). By marking their locations on the roadbed before the ties are laid, it is easier to see where you might run into problems.(Fig. 1a Fig. 1b) shows where the turnouts are located. The usual procedure is to mark the location of the point of the frog. However, where clearance for grade crossings or bridge rails at section joints is critical, it is more useful to mark the location of the points.

The frog of a turnout is that part where the rails cross in sort of an elongated "X". The portion of this structure where two rails join to form a "V" is termed the point of the frog. Turnout number is the distance one must travel along the diverging rails to gain one unit of separation between these rails.

Crossover layout is from frog point to frog point, measured diagonally. Length is determined by the length of track needed to join them together. The easiest way to fix the locations of the two turnouts in a crossover is to lay a template (usually packed with the turnouts) at the proposed location of the first turnout, then position the other turnout so that the connecting rails are lined up. The locations of the frogs (or switch points) are then marked.
For hand laid turnouts where ties are not provided, the following chart shows the tie lengths necessary for various frog numbers. The data is for 8'6" ties. For 8' ties, subtract 3/32" from each length; for 9' ties, add 3/32". Please note that the 

tie lengths are listed in order from the switch points. 

The next step is to mark the positions of the rest of the turnouts on the main line. The plan shows their location. Remember that switch points should be at least 3" from the edge of a module section. When you feel that the turnouts are in proper position, work can begin on the ties. We will begin with the #8 crossover on section A. If you are going to use code 100 track, American Models switches come with a template for locating the ties. This can be glued directly to the roadbed (ballast will hide the template later). Other brands of turnouts will require a tie laying jig or some other form of locating system. A tie jig is not difficult to build. It can be constructed from a 1 x 4 x 18" pine board. 

Grooves are sawn in the board about 1/16" deep and slightly wider than the ties (approximately 1/8"). 

The grooves are spaced on 5/16" centers. This will result in ties spaced 1 every 20 scale inches, which is prototypical. 

Another method for those who do not have a table saw, is to glue 5/32 x 1/16" spacers to a 1x 4 x 18" pine board, using 5/16" centers. (Use a tie to check the spacing; it should fit loosely between the spacers.) A similar jig can be made for sidings where 24" tie spacing is common in the prototype. Just make your spacers 3/8" wide.

Now place the ties on the jig beginning with the two 15' switch stand ties. Then, using the tie lengths in the table above, add the remaining ties until all are in place. Finally, lay a 1/2" wide strip of masking tape over the center of ties and lift them off the jig. This will look like the backbone of a fish. You are now ready to glue them to the roadbed. A waterproof glue (e.g., Elmer's Carpenters' Glue) should be used. It can be applied either to the ties or to the roadbed surface. Position the ties on the roadbed and, while the glue is still wet, lay the switch over the ties to check position. The switch points are usually located on the first 15' tie and the frog points may be on either the first or second 13' 6" tie. A little repositioning may be necessary.

For a crossover, simply repeat this process for the second turnout. Check to see that the ties are in proper place and then proceed with the remaining turnouts. The tie jig or the templates provided with the turnouts make this a simple job.

If you have designed your own track plan, make sure that your turnouts are not too close to the ends of the modules. Switch points must be at least 3" from the end of a module. This allows for 1" of stock rail beyond the points and 2" for the bridge rails used to connect tracks between modules.

When all of the turnout ties in section A in place, you are ready to lay the ties for the main line and siding. The tie jig for the switches is also used to ensure proper spacing for the mainline ties. Just lay the ties in the jig, pick them up with masking tape, and glue them on the roadbed, just as you did with the switches. The ties for the mainline track run to the edge of the module. 

If you are planning to use flex track you may want to consider replacing the final 2" (before the module's end) of plastic ties with wooden ones. This will give you 4" of wooden ties at the end of the module: 2" for the bridge rails and 2" where the rails of the flex track are spiked to the ties. This is something of a bother, but we have seen the rails ripped off plastic ties when modules are moved. It is less likely to happen with rails spiked to wooden ties and a lot easier to repair if it should be necessary.

Once all the ties are in place, you can start installing the turnouts. Two tools will be of help. One is the NASG track gage and the other is a three-point gage sold by Bill's Train Shop. Start with the crossovers to be sure that they fit together, then attend to the sidings. 

Traditionally, turnouts are installed stock rails first, then the frog and point rails. Since all of the commercially available turnouts are pre-assembled with straps soldered to either the tops or bottoms of the rails, these are fairly easy to install. 

The job of installing turnouts demands care. Start by spiking the turnout in a few places, then remove the straps. Sam Powell recommends prying the straps off with a screwdriver. Once these are removed, you can finish spiking the turnout in place. The best spikes for the job seem to be Rail Craft Small Spikes. Once you get the hang of inserting them without bending, they will look 100% better than any other spike.

Once the turnouts are installed, the rest of the track can be added. Hand laid track can be code 100, 125, 148, or 172. Ace plastic ties are available for 125 and 148 rail and are self-gauging. Rail in various weights is available from most hobby shops, as are ties and spikes. Don't forget to pick up a package of rail joiners while you are there. Flex track is available from Tomalco and Hoquat Hobbies. The NASG and BTS gages are necessary tools, also.

With everything in gauge, your module will be ready for switch throws and wiring, which is the subject of the next installment: Electrical.

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