Turnout Tips

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Turnout Radius Information

The RPs for modules is a 32" radius on the mainline and 24" on spurs and #6 turnouts on the mainline. Although there is some variance, the turnout number and radius are as follows: # 4 is 15", #5 is 26", and #6 is 43". You can see that the #6 is overkill and the #4 is way below minimums and totally unacceptable. #4's should never be used on the mainline and rarely within the back track. We have found that #5's are adequate and do not waste as much space as 6's do. Atlas custom-line #4's are actually #5's.

Turnout Tune-Ups

1. TESTING
   I recommend that the turnouts and track-work be "tested by fire" (in a show) before the track is ballasted to test for problems. After gluing, fixing issues is much more difficult. Let's not use a "paying show" for this.
2. GENERAL COMMENT ABOUT BRANDS
   Peco turnouts seems to be one of the best overall in the code 100 size. Unfortunately they are NOT built to NMRA standards. As near as I can tell, two areas where they deviate is in the overall height and in the guard rail width. Peco turnouts with plastic frogs may have a bump built in where the frog meets the rail. This needs to be eliminated. Finally, Peco insulfrog turnouts may be made such that the two rails leading into the frog are of different heights. This will allow the wheels to reach across to the higher rail and cause shorts. File flat.
3. ELECTRO VS INSULFROG
   There are advantages to each. Having more experience now with DCC, I believe that MODIFIED Electro-Frogs are far superior, especially if the frog is powered through a remote switch that also moves the points and the moveable points are isolated from the frog and wired to the adjacent rails. HOWEVER, IF THE POINTS ARE CONNECTED BY A METAL BAR, THIS HAS TO BE REPLACED. When set up properly, there can be no accidental shorts and if the turnout is approached with the points in the other direction, a short will stop the train. Correcting the point direction is far easier than correcting a derailment, a compelling advantage.
4. FROG SHORTS
   When using the Peco insulfrog, shorts frequently occur where the two rails meet at the frog. They are made with a very thin insulating strip between them. Our NMRA RP25 wheels will reach across and cause a short. We have fixed these three ways. One is to paint a short (1/2") tip of each rail. The other fix is to narrow the space in the guardrail; however the paint t is gradually removed during track cleaning. The last fix is to convert the turnout to an Electro frog.
5. GUARD RAIL SPACING
   Peco turnouts use European standards that have wider guard rail spacing. This may need to be shimmed out to prevent picking the points and prevent shorts on Peco insulfrog turnouts.
6. FLAT SURFACES
   Make sure that the surface is perfectly flat. Occasionally debris from drilling the hole or fragments of cork will get under the roadbed and cause lumps. Of course avoid turnouts on or near a grade. When spiking onto a plywood sub-roadbed, it may be necessary to pre-drill the spike holes. Also after spiking, make sure to press different parts of the turnout down to see if it is tight.
7. TRACK HEIGHT
   Not all track and turnouts are exactly the same height. For example Peco track and turnouts are distinctly higher than Atlas track and turnouts. It is always necessary to shim up the track while soldering the joiners. When using Peco turnouts with Atlas Flextrack (any except Peco track) you must shim up the flextrack so that a bump is not created. The guard rail width is mentioned below (see GUARD RAIL SPACING and FROG SHORTS).
8. GAUGE
   The gauge is very critical for turnouts. Check each turnout thoroughly with the NMRA standards gauge.
9. FLASH
   Many turnouts use plastic to hold or make up the frog. In some areas, this plastic has excess flash that can interfere with the flanges causing derailments or bounce. Use a sharp knife to remove any flash.
10. FROG DEPTH
    On some turnouts the depth is large enough that the wheel actually drops down into a hole when passing through. Use a piece of 0.010 x 0.125 styrene strip cut to fit snuggly into the opening to fix this problem. A small spot of ACC will hold the shim in place.
11. POINT TIPS
    The points usually need to be slightly rounded and filed lengthwise to get a smoother blend with the stock rail.
12. POINT HEIGHT
    Amazingly the points are often lower that the stock rail allowing the wheels to ride up and over the points. This can be fixed by gluing a 0.010 shim to the bottom of the diverging point rail. Be extra careful when gluing around the throw bar and the points so that they don't get any glue on them.
13. POINT CONTACTS
    Once the points are powered through a remote switch, the contact shoes (at the tip of the points) are no longer necessary and should be removed. If left, they may cause the points to stay open and even momentary shorts.
14. FREE OPERATION OF THE THROW BAR.
    Before hooking up the linkage that moves the points, check for free motion. Often there are small burrs on the throw bar or on the plastic ties that restrict the movement. Also, I like to cut a groove in the roadbed where the throw bar will be to prevent friction. Avoid any chance to get ballast glue in the throw bar area. Some people put oil on the throw-bar and hinges prior to ballasting.
15. UNINTERRUPTED POWER TO ALL POINTS OF TURNOUT
    Out of the box turnouts usually receive their power via a hinge joint that is kind of loose and/or a tiny contact shoes under the tips that contact the stock rails. Both of these may work at first, but time and ballasting eventually interferes with good electrical contact resulting in dead points. The simple solution is to supply power to the frog with a remote switch and to wire the points and their support track to the stock rail. Be sure to add the necessary gaps.

Mission Statement

Promote participation, sharing, railroad history, and the NMRA/4 Div.
Entertain and inform people about the hobby.
Help charities, community organizations, and other railroad groups.

Outside Sources

NMRA Turnout Dimensions
link to NMRA turnout standards

Choosing Turnouts
Model Railroader on all-live or power-routing turnouts

Wiring Turnouts
Wiring for DCC's take on turnouts

"Model Railroader" 8/97, Types of Turnouts

"Model Railroader" 2/2001, Fixing Shinohara for DCC

"Model Railroader" 2/2002, Banish Derailments

Last updated:

April 11, 20087