A tale of three turnouts (2)–my approach to turnout building

While this story was about three turnouts, all were built in the same way. Here’s how I did it.

With the rails for the straight route in place, it’s time to establish the diverging route through a turnout.  The next rail laid will be that of the diverging route.

I use offsets to determine the routing of the curved closure rail through the turnout. Both NMRA and the prototype CN turnout data that I use give these offsets.  NMRA recommended practice RP-12x available for free download at

http://www.nmra.org/index-nmra-standards-and-recommended-practices

gives their standard turnout data for many model rail scales.

CN no. 7 turnout offset diagram

CN no. 7 turnout offset diagram.  From the point of the frog in this example, measure towards the switch points a scale 56′-1″ using a scale rule.  This is the location of the toe, or the tip of the switch points.  With this established, use a fine-tip marker pen to mark the location of the offsets and the toe of the switch.

SAFETY FIRST.   Wear eye protection.  DO NOT solder or use any power tool without wearing the appropriate safety glasses or goggles. 

Ask yourselfhow much do you value your eyesight? 

Curve some rail gently, then starting at the frog, measure carefully at each offset while you solder this curved closure rail in place.  Be as accurate as you can.  I use separate switch points, so the curved closure rail ends a scale 11′ from the toe (tip) of the switch points.

CN no. 7 turnout diagram detail of bend in stock rail

When laying turnouts by hand, it’s necessary to bend the stock rail of the diverging route to receive the switch point for the straight route.  This CN standard no. 7 turnout diagram shows how it’s done on the real railway.  Bending the diverging route’s stock rail ahead of the points in this fashion is a common practice on North American railroads;  UK railways use a “joggled” double bend, see–http://www.templot.com/martweb/gs_realtrack.htm

The stock rail is bent per the above diagram for the no. 7 turnouts that I am laying. This is followed by filing off the base of the rail for a scale ten feet or so at this bend to receive the switch point.  I place the bend of the stock rail about a scale nine inches from where the tip of the switch point will go.  Using an NMRA Standards Gauge to make sure that I am laying this rail down true to gauge, I solder the stock rail in place for the diverging route, gauging off the previously laid curved closure rail.  As I am using Code 88 wheelesets on my rolling stock, I lay as tight a gauge as possible through the turnout.

1935

Point end of an HO scale CN no. 7 turnout, showing bend in stock rail to receive switch point for straight route.  The base of this point for the normal route is soldered to the PC board throw-bar for strength;  the point for the diverging route is soldered to a Detail Associates’ .010″ x .018″ brass wire spike-shaped pin which is inserted into a slot drilled into the throw-bar.  This allows the pin to move while still maintaining this point’s location relative to the stock rail.  A little tweaking is still needed, as this layout has been in storage and the point for the straight route has gotten bent a little.  

With only the switch points to be installed, I drill a 1/16″ diameter hole between the ties at the heel end of the point location.  In this hole goes a short piece of 1/16″ o.d. brass or copper tubing.  A longer piece of 1/32″ diameter brass wire is bent 90 degrees at one end for about 1/8″ to form a support leg for the base of the rail at the heel of the switch point to be soldered to, and a hinge pin for the point.  I tin rail base and that 1/8″ long wire leg, then drop the wire through the tube.  The bent part of the wire is held in place to solder the rail to it by a spare switch tie on top of the rails.  It’s then an easy matter to solder the rail to the wire, judging by eye the location of this rail to line it up with its mating closure rail.

Take out the tie and drop the point into place.  Move the point around and check for binding, adzing off a thin layer of wood from the top of any tie that it binds on.  Do the same for the other switch point.

Cut a PC board throw-bar to length.  Drill a hole in the middle of it to receive the wire from your choice of switch-throwing device–Blue Point, Cobalt, Tortoise, slide switch, etc….

Take out the switch points and drill three 1/8″ diameter holes between the scale 16′ long headblock ties that are at the toe of the switch, between the stock rails.  I use a Dremel-type drill for this, using slight side pressure to connect the holes to form a 3/8″ long slot between the ties for the throw wire between throw-bar and switch machine.  Take your time; it’s easy to break a drill bit when abusing it like this.  Alternatively, you can use a Dremel milling bit to connect the holes to form a slot.

Take the PC board throw-bar and be sure to gap it on both sides before sliding it in place between the headblock ties.  Replace the switch points, and solder the base of the point for the normal route through the turnout to the throw-bar.  Move the point back and forth, ensuring that the throw-bar does not bind.

The point for the diverging route is soldered to a piece of pre-tinned Detail Associates’ wire as in the above photo.  A piece of tie with a hole drilled in it holds the wire pin while soldering it to the base of the rail in the same manner as a track spike. Drop this pin/point assembly into the throw-bar and check for binding.  If this assembly does not bind, you can insert the throw wire into the throw bar and connect it to your choice of switch machine or hand throw device under the roadbed.  The throw wire should not protrude more than a few thou above the throw-bar, and must not protrude above the top of the rails.  Check for binding of the throw wire in the slot that you’d cut in the roadbed.

1937

The completed turnout, built following CN no. 7 turnout diagrams and plans. Looking a bit rough after soldering the rails in place, a little cosmetic titivation is needed to improve its appearance.  Another layer of ballast, especially! 

1932-2

A look at the frog and guardrails.  Following CN practice, the guardrails are the same 11′ length as the points of this turnout. The centre-point of the guardrails must be located at the point of the frog. The paper template under the turnout did not line up perfectly with the established track centrelines; I used it merely for tie spacing here.

And now, off to something new…

 

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