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Improving Peco Turnouts for DCC
By Paul Anderson
This web page was last updated on June 30th, 2011

Peco Insulfrog Long Turnouts have a minor problem in the frog area. The exit rails coming out of the frog are very close together and the wheel tread of an engine can bridge the gap causing a brief short. This problem only seems to affect the long turnout even though the short and medium turnouts have the same geometry and angle (12 degrees) in the frog. With the medium and short turnouts when the rails are placed in the mould for injecting the plastic they aren’t inserted as deep giving more clearance between them.

For analog and most DCC equipped locos this is not a problem. There is a small spark but the short is so brief that it does not trip the short protection of the power station and the loco carries on with no problem.

For some sound equipped locomotives it is a different story. The slightest glitch in the power and the decoder resets to the beginning. You now have to wait for the engine to restart and then it starts to accelerate back to its speed setting before the interruption. If you have a lot of momentum set in the CV then it may take a while to get going only to have the next wheel hit the same point and short again shutting down the decoder. If the flywheel did not have enough revs then the loco will now be stalled on the short and you will have to get out the 0-5-0 and push it clear.

One fix for this problem that some people use, is to apply a little dab of paint or nail polish to the rails in the frog area to insulate them. This will work but is only temporary since with track cleaning and wear from wheels the paint eventually wears down and the problem reoccurs. Worn paint also becomes dirt on the wheels of your locomotive which causes poor contact.

My solution is to permanently modify the frog area by grinding down the rails and filling it with a good quality epoxy in the potential short area.

The diagram shows where the potential problem area in the frog is and from the picture of the unmodified turnout you can see how close the rails are together.

I used a 1/8” Carbide router bit with cutters on the end of the bit in my Dremel Tool (they also come with a plain end but you cannot plunge them into your work). I milled down the area between the lines on the diagram about 20 thousandths of an inch.

Next fill this area with a good quality epoxy. I find that an epoxy with a 24-hour cure time produces a harder filling where as 5-minute epoxy tends to be softer with a sticky surface. I used the pointed end of a Bamboo Skewer as my applicator. Don’t worry about the lump above the rails (see picture) but take care that the sides are fairly smooth and there is no epoxy in the flangeways. Let the epoxy fully cure before moving on.

To file down the epoxy I used a small flat file with two pieces of Masking Tape wrapped around the surface about ” apart to protect the stock rails as you file. You only want a single layer of tape on the side of the file that you are going to use (see picture). File down the top of the Frog until it is level with rails. I used a thin flat file that would fit in the flangeways to trim the sides of the fill flush with the rail and the point of the Frog. At this point if you see any depressions in the filling, add a little more epoxy to the depression and let it cure and file again.

You should now have a much friendlier turnout for your layout now. I have done about 20 of these modifications so far with no problem and I know quite a few other Club members have done them on their own.