Peco G45 live frog conversion

[ntpntpntp]

I dropped by the Kent G Scale Society meet at Teynham today, and whilst admiring one of the layouts the topic of conversation turned to the Peco points and the problems with skates shorting on the point frogs (the layout was running under Massoth DCC).

Some time ago on the old G Scale Mad site I wrote up how I converted some Peco points to live frog. I've found the original photos and notes so thought I'd copy and paste them back up as a thread here in case anyone finds it useful.

It's not the only solutution to the shorting skate problem of course.

There is the simpler/cheaper (and perhaps more temporary) method of painting the frog tip area with varnish, but I felt that would increase the dead-spot.
Other folk have gone for a "half-n-half solution" where they've used a polarity changing switch, modified the wiring to bind the existing frog rails together and to the polarity switch, and used isolating fishplates. That works quite well.

Anyway, here's what I did...
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Having used live frog pointwork in N scale for many years, I thought I might as well have a go at converting one of these Peco points to have a live frog, and thus remove the problem of shorting skates. I reasoned I might also be able to reduce the ?dead spot? at the frog, for the benefit of small locos.
[/font]
So, two issues to resolve:[/size]

1) Rebuild the frog with metal rail, with the minimum of alteration.
2)[/font] Provide a means of switching the frog polarity when the point is thrown.


Task 1) rebuild the frog:

To rebuild the frog with metal, might as well use the existing frog rails as they?re already ground to the correct angle where they enter the plastic frog unit. First turn the point upside down and remove wire links bridging the rails underneath beyond the frog. I used a Dremel type tool to grind off and clean up the underside of the rail where the wire links were spot-welded. This will allow the frog rails to slide out from the chairs.

Remove the star washers holding the plastic frog unit in place.

(in the photo I?ve already done these operations)

Slide out the two frog rails. Remove the plastic frog unit. Carefully cut out and remove the entire ?tip? section of the frog.

The tip of the frog rail from the ?straight? side of the point will be the tip of the new frog. Grind about 15-20mm off the foot of the rail next to where it?s already ground to an angle. This is to allow the other frog rail to butt up properly.

 

[ntpntpntp]

Refit the ?straight? frog rail by sliding back into place, right up into the plastic frog unit.

[/font]
Refit the ?curve? frog rail also by sliding back into place until it butts up nicely and continues the angle ground into the ?straight? frog rail.[/size]

Both these rails will need to be cut to isolate the new frog from the rest of the trackwork. You can see I?ve pencil-marked where the rails will be cut. The frog rails where then both removed and cut to length, then refitted.

Cut and fit two new short lengths of rail (about 65mm) to make up the lost length of rail so all rails ends are even at the end of the point. Leave a suitable isolating gap.

 

[ntpntpntp]

Turn the point upside down again. Using a reasonably powerful soldering iron bond the two frog rails together to a single wire which will be fed to the frog polarity switch (see later). These soldered joints will also help to secure the rails in place.

That?s the frog conversion completed! Notice that this new frog has indeed reduced the ?dead spot? on the point by about a centimetre I reckon.

 

[ntpntpntp]

Task 2) fit a microswitch to change the frog polarity.

Now, there are probably many different ways a switch could be fitted, and of course some point motors come with an auxiliary changeover switch for just such a purpose (or one can be fitted).

In my case I wanted something that would work with the existing manually operated tie-bar. I had some old single pole changeover microswitches in my spares box. The main casing of these are about 2mm x 10mm x 6mm. By removing some of the plastic sleeper next to the tiebar the microswitch could be fitted next to the tiebar using hot-glue. A screw fitted to the underside of the tiebar actuates the lever on the microswitch. The two changeover poles of the microswitch are wired to the underside of the running rails, the common is connected to the wire coming from the frog.[/size]
[/font]
Obviously the way I?ve done the switching is not particularly weather proof, but for indoor use then I think it?s ?Job Done!? No doubt other folks can organise more suitable outdoor switching where needed.

Nick

 

[stockers]

Neat solution Nick. I think there were 40 points on that layout (Kent GSS have purchased a new running track. Its a three quarters finished project 26 x 10ft. Running today with a borrowed massoth 1200Z/Navigator control - brilliant day.

 

[dunnyrail]

Nick, your solution is pretty much as I have done since finding the shorting problems with LGB Skates. One angle that you have done better than me is to mound the switch as you have done. Mine way was more labour intensive and I have had one failure in the last 5 or so years. However I have used the micro switches outside with only one failure in all that time. I do put a cover over the top, not a box just some flet plastic card to keep the main crud and rain off.

Many thanks for posting the thread.
JonD

 

[jacobsgrandad]

Interstingly enough, I put the varnish on the original kent track after the burnout of the Heidi chip. This situation was when Heidi was being run under analogue control. stalled on the points and the controllers did not trip out hence it sat there and fried. On the new track today under massoth control we had some sparks but no stalling. My outdoor track is all peco. Have not touched them at all. Have done nothing to the locos and it all runs perfectly. No stalling, no sparking.

 

[jacobsgrandad]

PS like the look of the mod but there are a lot of points, initially the varnish trick may have to do.

 

[stockers]

On the new track today under massoth control we had some sparks but no stalling.

Actually, what started the concern today was the other loco (my mallet) on the other line stopping as the first loco created the spark. The massoth unit must have been having a hard time of it.

 

[dunnyrail]

Interstingly enough, I put the varnish on the original kent track after the burnout of the Heidi chip. This situation was when Heidi was being run under analogue control. stalled on the points and the controllers did not trip out hence it sat there and fried. On the new track today under massoth control we had some sparks but no stalling. My outdoor track is all peco. Have not touched them at all. Have done nothing to the locos and it all runs perfectly. No stalling, no sparking.

I think that you may be lucky with the Massoth. It also depends on the speed that you run the trains. I do lots of slow shunting and run rounds, hence the sparking/stalling was more apparent on the unconverted Peco's. Interestingly it can also a problem on the LGB R5 points on occasion.
JonD

 

[ntpntpntp]

... Interestingly it can also a problem on the LGB R5 points on occasion.

Can't say I've noticed a shorting problem on my R5's . I did have a problem with some small locos stalling on R5 frogs (especially my Maerklin Maxi with its small flanges). I wrote up a similar live frog conversion for R5 frogs in another thread on GSC. A bit more grinding and soldering work involved than with the Peco points!

 

[Gizzy]

Excellent thread Nick.

Could you have fitted isolating fishplates between the new frog and the running rails?

I realised that you glued the frog in place, but it looks a little flimsy....

 

[ntpntpntp]

Could you have fitted isolating fishplates between the new frog and the running rails?

I realised that you glued the frog in place, but it looks a little flimsy....

I think I did partially secure the plastic frog back in place with epoxy as one of the fixing prongs is lost when the V is cut away (the other prong and star washer was re-used), but other than that the rails are secured by the chairs and the soldered wiring.

I did wonder about some insulating fishplates where I'd cut and fitted the two short lengths of rail but they didn't seem necessary in the end once held by the wiring.

I converted a couple of points in this way for Doverles and he's had them outside at ground level for a couple of years now with no problems. He mounted the microswitch on a separate plinth with a cover, rather than underneath.

 

[dunnyrail]

Just looking at some of my unlaid converted points (I am squirreling them away for a new layout when I move) I remember that I fused the remaining spigot on the front with a soldering iron. On some of the points I also Araldited the frog in place. Plus on all my points I use Peco Insulated Fishplates for the two rail Joints on the point. Now I can put the points in place and all the wiring is done for DCC. I suppose that you could say that they are DCC Ready.
JoinD

 

[CoggesRailway]

Sorry for the dull question... but what exactly is the frog, are they normally live or dead, and what is the exact nature of the problem with the skates. I tried googling and just got a lot of amphibians. In amongst the amphibian jokes that are inevitably coming my way I would like a real answer as I genuinely don't get this.

I know that the points on my N layout would stop the trains if not set properly where as my LGB ones work differently but that is all i know.

 

[Bredebahn]

Sorry for the dull question... but what exactly is the frog, are they normally live or dead, and what is the exact nature of the problem with the skates. I tried googling and just got a lot of amphibians. In amongst the amphibian jokes that are inevitably coming my way I would like a real answer as I genuinely don't get this.

I know that the points on my N layout would stop the trains if not set properly where as my LGB ones work differently but that is all i know.

Probably a suitable topic for its' own thread, but the frog is the part of the point otherwise known as the nose or common crossing - where the rails actually cross one another. You can imagine that the problems for modellers are that when rails are used to carry traction current then at this part you have all the makings of a short circuit with rails of opposite polarity crossing one another - even if isolated with plastic to prevent a short circuit, it is very easy for a passing metal wheel to bridge the two opposing rails and cause a momentary short. This may not be sufficient to stop a train, but it can damage delicate circuit boards. The two ways of overcoming this problem are either to have a totally dead frog with the current only being live in the direction that the points are set, or the frog being wired as above so although the whole is live, again it is only one track that is energised and there is no conflict in the crossing rails. Live wiring is far better (particularly in the smaller scales) as it ensures a smooth transition as there are no big gaps to cross for the pickup wheels - live frog wiring generally requires wiring to be fed from the toe of each point. Off the top of my head explanation and I know that Neil could explain it much better than I, but that's the general idea!

 

[ntpntpntp]

The frog is the heart of a point including the V shaped bit where the two inner rails have to cross.

If both tracks out of the point are under power, and if those two inner rails are simply metal rail that come together and touch, you get a short circuit.

A "dead frog" gets around the short circuit problem by having a plastic V (or maybe a separate metal V that isn't electrically connected to the rest of the track). This makes wiring up the track simple but means that you have a dead spot that can cause short wheelbase locos to stall.

A "live frog" uses a separate metal V that is electrically connected, but has to be switched to one polarity or the other depending on which way the point is set. This makes the wiring a little more complicated (but not a problem once you grasp the idea) and of course having an electrically live metal V gives the best contact area for those little locos.

Have a look at this page, intended for DCC users, has a good diagram of a point, it's wiring and how to switch a live frog. http://www.wiringfordcc.com/switches.htm

<edit> Looks like John and I were typing our responses at the same time! </edit>

 

[ntpntpntp]

To answer the specific question regarding the problem with Peco point and skates: the Peco G45 points have a dead frog in that the very tip of the V is plastic, but the way the two metal rails lead into the V means that they end too close to each other - close enough that a skate passing along one of the rails overhangs far enough to touch the other rail and cause a short.

It's an unfortunate design feature - some might say design error given that LGB existed when the Peco points were introduced and you'd have thought LGB would have been considered as one of the likely ranges of models that would be run on the trackwork. Somehow I doubt it'll ever be corrected by Peco.

 

[CoggesRailway]

Thanks very much for the great answers chaps. I now know my frogs.

 

[bobg]

One last thing about frogs, dead ones are sometimes eaten.......... mostly by the French.



Sorry!!! exit stage left.