Hand Laid Gauge 1 Switches
Hand Laid Gauge 1 Switches
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This article takes up where the article on Hand Laid Gauge 1 Track left off. Can I really hand lay my own switches?
What are the parts of a switch and what do they do?
Stock rails - "stock" in the meaning "standard" or "unmodified." The outer stock rails (labelled "stock rail" in fig. 1) carry right on through the switch without modifications, at least in the prototype. On a model switch, they are often notched for the points. The inner stock rails (unlabelled in fig. 1) end at the frog on a prototype switch. On a model switch, they usually carry on right into the frog and meet to make the point of the frog. In our type of switch, the stock rails are exactly where they would be if the railroad had decided to build either one route or the other. There are some gaps in the stock rails where the switch is, but the parts of the rails that are present are right where they would be if only one of the routes had been built. This concept makes designing a switch very easy, as we will see later. Points - the moveable pieces of rail that determine which track the train will take are pointed at one end to smooth the transition from the stock rails. In model switches the term is often extended to include the rails themselves for the two pieces that move to divert the train from one route to the other. These moveable rails are also known as "point rails". They are often hinged at one end and moved by a throw bar at the other end. Closure Rails - In the prototype they are the rails from the frog to the points. In our model switches, they extend from the hinged end of the points through the frog and bend outwards to form the wing rails. Wing Rails - On prototype switches, the wing rails are forged as part of the frog. On our model switches the wing rails serve to anchor the ends of the closure rails as well as to guide wheel flanges onto the opposite wing rail. The ends of the wing rails are flared to make certain that wheel flanges are guided into the flangeways, the gaps between the wing rails and the stock rails. Guard Rails - Guard rails keep the outer wheels on the outside stock rails when the inner wheels are passing through the frog. Normally axles are guided by the outsides of their wheels' flanges. They are kept from moving to the left by the flange of the left wheel riding against the inside of the left-hand rail and they are kept from moving to the right by the flange of the right wheel riding against the inside of the right-hand rail. But in the frog there is a gap in one rail which leaves one wheel unrestrained and would allow the axle to move sideways. To prevent this, a guard rail is added which restrains the back of the flange of the wheel away from the frog to keep it from moving sideways. Thus one wheel alone keeps the axle from moving left or right. This can be a problem area - if the flangeway between the guard rail and the stock rail is too large compared to the wheel flange, the flange on the wheel opposite the guard rail can ride up on the stock rail, possibly derailing the car. If the flangeway is too narrow, it will pinch the flange, possibly skewing the truck and derailing the car. Of course, these problems can also occur if the wheels are out of gauge (i.e. the distance between flanges is not what it should be.) To compound the problem there are no common standards for flanges and flangeways in large scale so one manufacturer's switches may not work properly with another manufacturer's wheels. See How do I Check my Track and Wheels? on the Hand Laid Gauge 1 Track page for the standards worked out by the Saskatoon Railroad Modellers group for their railroads. Throw Bar - The throw bar is a connection between the point rails that allow you to "throw the switch," moving both point rails at the same time. Throw bars can be solidly attached to the point rails or must be free to pivot, depending on whether the hinges allow lateral movement or not. In prototype switches the closure rails are so long compared to their movement that hinges are not needed, either for the points or for the throw bar. Frog - called a frog because a prototype one seen apart from the rest of the switch looks a little bit like a prototype for Kermit. In a prototype switch it is a forging designed to bolt to four pieces of standard rail, the two inner stock rails and the two closure rails. The forging includes the wing rails. In the model switch, the frog is made up of extensions of the two stock rails and the two closure rails and the closure rails become the wing rails. Much mythology has built up around the switch frog, possibly because it is the one piece of a switch that most modellers recognise. Most of this mythology has little effect on operation and is perceptible only by purists. There are, however, two things that the modeller should be aware of. First is that the more acute the angle in the frog the less likely that trains will derail while passing through switches. For switches with one straight branch and one curved branch, this applies only to the curved branch. The angle is measured as a frog number equal to the distance between the rails divided by the distance from the point of the frog. Higher numbers are more acute and less likely to derail than lower numbers. In the switch diagrammed above, the inner stock rails are 10 mm apart at a distance of 35 mm from the point so the frog is a number 35/10 = 3.5 frog. The sharp-eyed among us will note that the diverging route is curved and so the exact number will depend on exactly how far from the frog we measure. This is true, but 3-1/2 is close enough. It does, however, bring up the second point to be aware of. On prototype switches the rails are always straight through the frog and for a distance on either side of it. On prototype switches, which have frog numbers of 12, 16, 20 or even higher, there is a lot of closure rail to allow it to bend slightly then straighten out again before the frog. In our model railroads, we often do not have the room for such large switches and so we build them curved from the points and right through the switch. This is a time-honoured tradition seen in Atlas Snap Switches and in Lionel switches. The penalty we pay is in a greater tendency to derail trains, particularly when backing at higher speeds through the diverging routes of switches. We can minimise the problems and still keep the switches reasonable in size by using relatively large radii. For engines like the Bachmann Tenwheeler, a radius of 5' has been found satisfactory. This is probably a little tight for an Aristo-Craft Pacific because of the added length, while two truck engines, whether diesels on Shays, will go through switches with an even smaller radius. Inside, Outside, Inner and Outer - The terms inside and outside are used extensively in this article to mean the side toward the centreline of the track and the side away from the centreline of the track respectively. For example, in fig.1, the outsides of the points can touch the insides of the stock rails. Inner is used to mean closer to the centreline of the switch and outer to mean farther from that centreline, for example the inner stock rails are closer to the centreline of the switch than the outer stock rails. This distinction becomes important near the frog, where the inside of the inner stock rail is away from the centreline of the switch but toward the centreline of the track. Confused? This distinction will make more sense as we proceed. How do I design a switch?
Laying a switch is easier and cutting a switch into existing track is much easier with track-laying templates, assuming you already have the templates at hand. It may still be easier even if you have to make the templates just for this job alone. If you do not have them , you can make your own track-laying templates out of styrene. The templates are used to lay out where the rails (actually the inside edges of the feet of the rails) would go if each route existed only by itself. Usually this will be a curved branch tangent to a straight mainline, but may also be a straight branch tangent to a curved main, a curved branch tangent to a curve of larger radius, a straight branch diverging at a very small angle from a straight main or wye switches with two branches both diverging from a straight main. These are all simple switches - compound switches, where the parts of one switch fall within the limits of another switch, and things like double slip switches, are beyond the scope of this article. To start, lay out a baseboard pattern on a large piece of cardboard. First lay out the intersecting routes using the templates. Add 1" to each side to mark the ends of the ties. Add another inch to each side to mark the outer edges of the baseboard. Check that the pattern extends at least 4" past the points i.e. past the point where the two routes just start to diverge. Check also that the pattern is 5-1/2" wide at this end to match standard baseboard. At the other end of the pattern, check that the pattern extends far enough past the point of the frog i.e. the point where the inner stock rails will meet, that both tracks have room for standard 5-1/2" baseboard. Cut out the pattern, trace on the pressure treated plywood you are using for baseboards, and cut out the switch base. Finish off the base by using a compass or 1" wide slat to mark the tie ends 1" in from the edge. Next add some ties to your baseboard. If you have a particular railway and particular era in mind, by all means lay your ties in the correct pattern. Otherwise use a generic pattern. See hand laid switch photos. You can cut a variety of cedar ties of the usual cross-section, but longer than normal in 1/2" increments. Then start laying down ties, starting 3/4" in from the end of the base nearest the points. Start off with normal ties, then switch to longer and longer ones to keep the ends out to the tie end marks. Space the ties the same as for your track, or a little less and keep the ties perpendicular to the straight through route. Nail the ties in place as you go**. Continue until you are past the frog point by two or three ties, then switch to standard ties to make two tie beds for the two diverging tracks. The initial standard ties of the curved route can be skewed and their ends may have to be interleaved with the ends of the ties on the straight route. Continue until the last ties are 3/4" in from the end of the baseboard. Use a straight edge to check that all your ties are the same height and sand them if they are not. Finish off the ties by transferring the track guide lines to the tops of the ties, using the templates. You have just designed a switch and have it drawn, full size, in the most useful possible place - right on top of the ties where the rails will be laid.
Conventional wisdom is to start with the frog and then add the rest of the switch. This is a reasonable approach but bear in mind that it is also possible to start with the outer stock rails and build the switch between them. That approach is often the best approach when cutting a new switch into an existing track. See hand laid switch photos. The point of the frog can be cut two different ways. Conventional wisdom says to cut the ends of both the inner stock rails at half the frog angle. This is shown in fig. 1A below.
In figure 1, the rails are seen from the top. The top of the head is hatched to differentiate it from the foot of the rail which is seen on both sides. Fig. 1A is a reasonable approach provided the rail can be soldered. With aluminum rail it results in a long, weak point that is easily damaged. A modified frog point as shown apart in figure 1B and assembled in figure 1C is cut at the full frog angle and is much stronger. To make your frog point start off with longer pieces of rail than you will need, to allow for adjustment. Pre-bend the curved rail to conform exactly to the outside of your track-laying template (you probably will not get an even bend right to the end of the rail so do what the rest of us do - chop off the last few inches and set it aside.) Then shape your frog point, checking frequently against the guidelines you have drawn on your ties. Rail can be shaped with a file if it is held horizontally in a vise with one foot clamped between the jaws or it can be shaped with a sander or grinder. Once you are happy with your frog point, install it by spiking the inner stock rails loosely in place inside your guidelines. Next slide the rails lengthways until the shaped ends meet properly. Then spike the rails firmly in place. You are now ready to start laying the outer stock rails. Bend the curved outer stock rail as required to fit your pattern and spike it temporarily in place using only enough spikes to keep it on your guide lines. Where it parallels the already installed inner stock rail, use your track gauge to set the proper spacing. Similarly install the straight outer stock rail, using your gauge to space it properly from the stock rails already laid. Now make alignment marks on the rails and ties, using perhaps scratches on the feet of the rails and corresponding pencil marks on the ties. Then locate the ends of the points, where the guidelines for the outer stock rails meet the guidelines for the inner stock rails. Often these will not be exactly opposite one another - just take an average position. Mark the ends of the points on the insides of the stock rails. Then mark the notch to be cut out of the inside of the curved stock rail by laying a straight edge from the end-of-points mark to the point of the frog. The corner of the straight edge should be on top of the rail foot, tight against the vertical web at the end-of-points mark. If you use an extremely thin straight edge, you may be able to mark the notch on top of the rail foot using a sharp pencil. With a not quite so thin straight edge, a scriber made by heating a #ll Xacto blade red hot and bending over the last 1/8" to an angle of 45 degrees works wonders. Remove the curved outer stock rail and grind or file the notch. When correctly done, the rail head will be removed not farther than the edge of the web at the points end of the notch. Use the notch in the curved outer stock rail to lay out the notch in the straight outside stock rail. Replace the outer stock rails, aligning your marks, but do not spike them down too heavily just yet. Now it is time to lay the closure rails. Start off with the straight closure rail. Using a hacksaw, cut a notch in the outside foot of a piece of rail about 1/2" from the end and another about 3" from the end. Bend the rail toward the notches in both places to form the wing rail on the end of the closure rail. The notches and bends are clearly visible in fig.3 of hand laid switch photos. Check the closure rail against your plan and adjust the angle of the wing rail as required. If the gap closes up before you can bend the rail far enough, re-cut the gap. When you are satisfied, temporarily hold your closure rail in place. If you are using code 250 rail, make sure you have some spikes near the frog point to properly space the foot of the wing rail away from the foot of the inner stock rail. But if you are using code 332 rail, make sure you remove any spikes that would prevent the foot of the wing rail from butting up tight against the foot of the inner stock rail. With the closure rail still in place, mark it for length at a point about 1/3 of the distance from the frog point to the points. Ideally this should be half way across a tie or fully across one of a pair of ties. Cut the rail to length and spike it loosely in place spaced exactly from the straight outer stock rail. Check that it lines up with the straight inner stock rail by laying a straight edge along it to the frog point and a little beyond. Then move it lengthways until the wing rail is in position, tight against the frog point spikes (code 250) or foot to foot with the curved inner stock rail (code 332.) Tighten the spikes to keep the rail in place. Add some spikes in holes drilled in the foot of the rail, one on each side at the free end and two at the wing rail end. ** For code 250 rail, put the drilled spikes in the outside foot of the wing rail while for code 332, put them on the inside. Add some drilled spikes to the frog point while you are at it. Use regular spiking on the opposite side of the wing rail. Repeat this procedure for the curved closure rail. It helps to first bend the rail to match the outside of your track-laying template, bending at least enough extra to later make the curved point rail. Start your bend at the wing rail end so that the recalcitrant end piece that does not want to bend properly will be formed into the wing rail.
To make your creation act like a switch, you will have to do something to keep wheel flanges from taking the wrong path when they go through the frog. That something is guard rails. You can use scraps of rail 3" to 4" long. Make a hacksaw cut 1/2" in from each end and bend the rail just like you did for the wing rails. Spike these guard rails down opposite the open area in the frog, using the same spacing as you did for the wing rails, spike between the feet for code 250 rail, butted feet for code 332 rail. Lastly, you can add a throw bar to make it easy to throw your switch. The throw bar should be located about the mid point of the points rails or a little closer to the points. If you used switch blocks (extended ties for a switch throw), put the tie bar between them. Otherwise place it between two convenient ties. Cut a piece of bakelite, hardwood, or plastic to fit loosely between the selected ties, making it a bit longer than the ties. Centre the throw bar under the rails and set both points open about 1/8". If you are using code 332 rail, drill down through the centers of the points rails and through the throw bar with a #50 drill (tap drill for #2-56 machine screw.) In practice it may be easier to make marks on the points rails where they cross the centreline of the throw bar, then remove them for drilling. When you have the points rails drilled, you can reinstall them temporarily, position them 1/8" open, and drill down through the throw bar and into the baseboard, working through the hole in the rail. If you have a spare #50 drill, push it through the rail and into the throw bar and the hole below to keep everything lined up while you drill the second hole working through the other rail. Also drill the second hole down into the base board. Now remove the throw bar and re-drill it to clear #2-56 machine screws and add any other holes you might want (a 5/64" hole near one end for a throw rod for example.) Enlarge the #50 holes you drilled in the baseboard to about 3/8" by first enlarging them with a 3/32" drill. Tap the holes in the points rails 2-56 and reinstall them for the last time. Position the throw bar under the points rails and run in a pair of 2-56 brass machine screws working through the 3/8" holes. You might find it helpful to temporarily glue the screws to you screw driver while doing this. Leave the screws about 1/2 turn looser than snug and cut off any part that projects through the tops of the rails. A drop of a.c.c. applied to the screws at the tops of the rails (or at the sides if the threads show) will lock them in place. For code 250 rail, you can attach a wooden throw bar using pairs of spikes or escutcheon pins, one each side of the rail foot or you might try pairs of #0 machine screws tapped downward into a bakelite throw bar. For code 250 brass or nickel silver rail, you can solder tabs under these ends of the points rails too, and use wood screws or machine screws to attach them to the throw bar. Congratulations - you have just completed a hand laid switch! How do I wire my switch?
A much better approach is to use a toggle switch to mechanically throw the points and to switch the power. A full size double pole double throw toggle switch, one that mounts in a 1/2" hole, is what is needed here. Mount the switch with the toggle pointed skyward about 3 inches from the end of the throw bar. This can be seen in Figs. 2 and 4 of hand laid switch photos, where an aluminum plate was used to mount the switch. Next select a piece of brass tubing that will just slide over the toggle and cut a 2" length. Solder a brass tab about 1/4" to 3/8" square centered 1/2" from the end of the tubing, at right angles to the tubing (rather like a flag on a flag pole.) Drill a 5/64" hole through the middle of the tab to accommodate a throw rod. Slip the tubing temporarily over the toggle, tab end down, and bend up a piece of 14 gauge copper wire to act as a throw rod, connecting the tab to the end of the throw bar. Adjust the tubing on the toggle and adjust the length of the throw rod until both the toggle switch and the track switch throw fully in both directions. If you cannot slip the tubing far enough down over the toggle to achieve this, cut a little off the bottom of the tubing and try again. When you are satisfied, fix the tubing to the toggle using epoxy or by soldering. DO NOT let solder or epoxy flow down into the toggle switch! Putty can be used as a dam with epoxy or wet tissue can be used with solder. Note that many toggles are chrome plated brass - the plating will have to be filed off for easy soldering. Now that you have the toggle and track switches mechanically linked, it is time to wire them together. Only one side (3 contacts in a row) of the toggle switch is used to switch the frog. The center contact connects to the frog i.e. to all four rails that make up the frog bonded or soldered together. The contact closest to the track switch connects to the outside stock rail closest to the toggle switch. Then the contact farthest from the track switch connects to the outside stock rail farthest from the toggle switch. Sometimes the internal wiring of the toggle switch is reversed so if this wiring causes your railroad to electrically malfunction when trains reach your track switch, try reversing the connections to the two outer contacts on the toggle switch. Finally, bond the point rails to the adjacent stock rails, not to the frog. This will avoid any shorting that might occur when long wheel base engines cross the switch and is a must for command control (the switches shown on the photo page were later converted to this style of bonding for just that reason.) There must be no direct connection between the point rails and the frog and the gap between the point rails and their closure rails should be examined to make sure no sneak paths exist here. Without getting too much into layout wiring, it should be mentioned that there are normally gaps in both inner stock rails but not in the outer stock rails. There are exceptions, for example when an arm of a switch feeds a stub (one ended) siding it does not need any gaps in that arm because these are route-selective switches and will automatically route power to a siding only when aligned for it; or for example when the switch is at a return loop where gaps in both inner and outer stock rails are required. Where can I learn more?
All about turnouts, Jim Hediger, Model Railroader magazine, August 1997, pp.60-61. Some good figures, including a photo illustrating the difference between a prototypical switch that is straight through the frog and a switch that curves throughout the diverging route. Handlaying track on the Crown Mountain Division, Lee Vande Visse, Model Railroader magazine, May 1991, pp. 96-99. The idea of using printed circuit board ties could be adapted to #1-gauge, particularly if brass strips were used on a layout that was not powered through the rails. Building a turnout from scratch, Tony Koester, Model Railroader magazine, December 1989, pp. 104-113. If you can read only one other article on handlaid switches, this should be the one. Introducing the F&S Junction, Michael Tylick, Model Railroader magazine, September 1989, pp. 61-64. The author's pragmatic approach to HO gauge switch design is similar to the approach taken here for gauge 1 switches. Two-rail wiring, Andy Sperandeo, Model Railroader magazine, March 1981, pp. 110-112. More details on wiring switches, including reverse loops. What about crossings?
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figure 1
figure 1 - the Frog Point,
plan view