Cutting point blades from the frog

[rynd2it]

My 009 layout has a couple of dodgy (read botched) SL-E497 Y points and I cannot get a couple of locos to traverse them reliably so I am left with the need to replace them. Not a big issue but as I have some very small 0-4-0 locos I need the live frog and it needs to be switched. I had solved this on the larger points by cutting the rails just behind the frog and then bonding the point blades to the adjacent stock rails. However, trying to do this with the shorter Y point damaged the piece between the blade and the frog.

 

The problems seem to arise from two things, a) the cutting disc was to large a diameter and b) the heat generated melted the  sleepers a bit and messed up the alignment. So, having ordered my replacements, how would you guys recommend making the necessary cuts? Is there a much smaller diameter Dremel cutting wheel available?  Or....?

 

 

 

 

 

 

[mezzoman253]

I found this difficult with a Dremel on 00 gauge, so I used a jewelers saw. You can get a vertical cut rather than a slightly angled one. It filled the gaps with plasticard superglued in, and sanded the profile to match the rail.

 

HTH Rob

[rynd2it]

2 minutes ago, mezzoman253 said:

I found this difficult with a Dremel on 00 gauge, so I used a jewelers saw. You can get a vertical cut rather than a slightly angled one. It filled the gaps with plasticard superglued in, and sanded the profile to match the rail.

 

HTH Rob

Thanks, I had looked at that option and I think it is the best. The original attempts were done with the points already laid which left the Dremel as the only way.

 

[RexAshton]

I used a piercing saw with a fine blade on my code 55 N gauge points but take your time and let the saw do all the work.

[Izzy]

You can get fairly cheaply, and I use, diamond needle files. Machine mart used to do a pack at around £10. Using a thin V edge and file vertically you can make a gap by doing both sides of the rail, so the gap isn’t too big. Doesn’t harm the other rails as the disc cutters can if you’re not careful.

[rynd2it]

8 hours ago, RexAshton said:

I used a piercing saw with a fine blade on my code 55 N gauge points but take your time and let the saw do all the work.

When you say "fine blade" are you referring to the number of teeth per inch or another dimension?

 

Thanks

 

[rynd2it]

2 minutes ago, Izzy said:

You can get fairly cheaply, and I use, diamond needle files. Machine mart used to do a pack at around £10. Using a thin V edge and file vertically you can make a gap by doing both sides of the rail, so the gap isn’t too big. Doesn’t harm the other rails as the disc cutters can if you’re not careful.

The problem I had with these Y points is that you are cutting through the tiny piece next to the blade pivot and that little piece can easily break off leaving a massive gap to be filled with something. The regular point has an extra sleeper to anchor the rail and wasn't an issue.

 

I'm acquiring a jeweller saw so we'll see how it goes.

 

Thanks

[Izzy]

1 hour ago, rynd2it said:

The problem I had with these Y points is that you are cutting through the tiny piece next to the blade pivot and that little piece can easily break off leaving a massive gap to be filled with something. The regular point has an extra sleeper to anchor the rail and wasn't an issue.

 Ah yes, see what you mean. Could you possibly replace the fishplates used as the pivots with isolating/plastic ones? Not sure if this would be possible. But then no cutting would be needed and the blades would be isolated and could be bonded to the stock rails.

[rynd2it]

30 minutes ago, Izzy said:

 Ah yes, see what you mean. Could you possibly replace the fishplates used as the pivots with isolating/plastic ones? Not sure if this would be possible. But then no cutting would be needed and the blades would be isolated and could be bonded to the stock rails.

There are no fishplates as such. The blade rail is made with a small extension pointing down and that slots into a small plate. The end of the frog rail is also mounted that way. I'll see if I can get a photo of the joint

 

[Nile]

Why not just wire it up as Peco recommends? I don't see the need to cut any rails.

[rynd2it]

23 minutes ago, Nile said:

Why not just wire it up as Peco recommends? I don't see the need to cut any rails.

Because if you connect the blades rails to the adjacent stock rail you'll get a dead short. The frog has to be isolated from the blade rails. Peco relies on blade to stock rail to power the frog, not reliable.

 

Edited December 15, 2021 by rynd2it

[Nile]

9 minutes ago, rynd2it said:

Because if you connect the blades rails to the adjacent stock rail ....

That's not part of Peco's wiring .

 

10 minutes ago, rynd2it said:

Peco relies on blade to stock rail to power the frog

Not if it's connected to a switch, which is what you must be doing for the above mods to work.

 

Are you using DC or DCC to power this layout?

[rynd2it]

10 minutes ago, Nile said:

That's not part of Peco's wiring .

 

Not if it's connected to a switch, which is what you must be doing for the above mods to work.

 

Are you using DC or DCC to power this layout?

I'm not going to argue this, it's well documented elsewhere.

 

[rynd2it]

1 hour ago, Nile said:

That's not part of Peco's wiring .

 

Not if it's connected to a switch, which is what you must be doing for the above mods to work.

 

Are you using DC or DCC to power this layout?

 

OK, to settle this. The diagram below is how to wire a Peco Electrofrog point especially for DCC. Note Peco says cut the jumpers however, on the 009 points, there are no jumpers so the rails have to be cut. The layout is wired for DCC but it can run DC instead if I choose

 

 

I will agree that using a switch to power the blade rails in line with the frog could work however that runs the risk of a short if a wheel on the stock rail should accidentally touch the adjacent open blade rail - both blade rails having the same polarity. Using the method below eliminates this risk.

 

 

Edited December 15, 2021 by rynd2it

[Nile]

I've not had a problem with the theoretical short circuit at the point blade, but the experience of others may be different. In the past I've done this modification with the older style points by replacing the fishplate hinges with insulated ones, not possible with the current ones. I don't bother now as I don't find it necessary. 

[RedgateModels]

3 hours ago, Nile said:

I've not had a problem with the theoretical short circuit at the point blade, but the experience of others may be different. In the past I've done this modification with the older style points by replacing the fishplate hinges with insulated ones, not possible with the current ones. I don't bother now as I don't find it necessary. 

Agreed, on my fledgling narrow gauge track work I’ve just removed the overcentre spring as I’m using servos. Whole frog and blades are polarity switched using a microswitch 

 

https://www.rmweb.co.uk/community/index.php?/blogs/entry/22850-the-trackwork-is-for-turning/

Edited December 15, 2021 by RedgateModels

[RexAshton]

8 hours ago, rynd2it said:

When you say "fine blade" are you referring to the number of teeth per inch or another dimension?

 

Thanks

 

Yes. The more teeth per inch the better.

[rynd2it]

Food for thought, thank you all.

 

In particular, the idea of having both the point blades and frog switched appeals to me as it's a lot less work and does not risk damaging the points and ruining the running capabilities. I think I'm going to give this a go especially as I have replaced all the rolling stock wheels with more modern finer flanges etc.

 

I will report back when I have done the tests - just waiting for the points to arrive.

 

 

[Izzy]

I think, but aren’t sure, that the troubles with btb shorting is primarily to do with OO gauge when it has happened. Although I mainly use hand built track in 2/4/7mm I have used DCC in N with Peco track & both live/dead frogs without any problems. I do wonder if it might occur with a particular combination, long fixed wheelbase steam locos and very tight radius - set track - points. It’s just a thought. N mechs on OO9 track  could well be just fine. Could you test things before laying the track down at all? Join a few lengths of track up to the ends of the points, run a few locos through. 

[rynd2it]

From the above dialog it was suggested that on 009 Peco points it was unnecessary to separate the frog from the switch blades. As my efforts to make the separation had resulted in poor running, I purchased four new points and installed them on the layout. The attached diagram shows this section of the layout – the wiring has not changed just that the switch blades are now electrically connected to the frog and each other. There is no bonding between the blades and stock rails other than physical contact when the blades move. Frog polarity is set by micro switches on the servo mounts.

Following final setting of the servos, I was adjusting the micro switches and observed I had a dead short between red and black, the position of the micro switch did not alter this. I have isolated the wiring to the micro switches to the stage when nothing else other than the two switches are connected to the track wires – the relevant track wires are (temporarily) isolated from the rest of the layout. The short occurs when the switch on Point A is closed, connecting the from to the red circuit and the point blades are set the same – touching the red rail.

I have been checking all the wiring carefully and cannot see a problem, however I did observe that when I operated point B the short went away. I need to do more testing to document which combinations of straight or divert on each point create or eliminate the short as there is clearly interaction somewhere.

In the meantime, can anyone shed any light on what is happening and/or suggest a course of action?

[rynd2it]

Well after several hours of head scratching and experiments I found the cause, almost by accident. Having removed all the frog switching wiring and still seeing the short it had to be the track. I finally found the culprit, an original point laid many years ago (not by me) did not have an IRJ on the frog so when I installed the new point at A, I put IRJs on my frog rails but not (obviously) on the stock rail. Fortunately the old point was actually set for the loop, not the siding, otherwise the short would not have shown up until much later. Lesson learned again, always put IRJs on frog rails, you can always feed the departing tracks if necessary

[DCB]

It looks like a lot of complication has been added and has made the system prone to shorts.   The Peco electro frog points are absolutely fine as standard as long as you keep them dry and make sure the wheel flanges go through rather than over the check rails.  If they fit through the check rails they don't short on the point blades. 

As drawn there are four potential shorts.  Usual doctrine is feed the points from the toe.  (or by extension the outer rails) As soon as you get feeds at the rails from the point frogs you will get shorts when wheels bridge the joiners. Its 99.9% certain you will run into the wrong end of a point at some stage and get shorts.  Even with DC these same side shorts can damage locos and the contacts on the point blades.  The extra feeds are only really needed for DCC Sound and Lights needing to be on when stock is parked up or if for some reason you want to shunt on a siding with points set against it. 

If you don't modify the points, don't need DCC sound and lights and don't want to run up and down the siding with points set against it or play with it in the rain (like I do) you only need two isolators at the top of your original diagram where there were none, and two feeds. 

Some people like complication I like reliability. 

[rynd2it]

The confusion, as you put it, was caused by the fact that the 009 points are constructed differently to the OO and even the EM one. On those points, the moving blade rails are already electrically disconnected by isolation blocks in the frog rails leading to the blades. This means that the blades need to be bonded to their adjacent stock rail for reliable connectivity. Peco provides for this on the OO and EM points but NOT on the 009.

 

To achieve the same result it would be necessary to cut through the blade/frog rails which is just possible on the regular left/right SL-E491/2 points but almost impossible to achieve without damage on the SL-E497. Hence my original post regarding making the cuts. During the ensuing dialog it was deemed that it was unnecessary to make the cuts, leaving both blades to be the same polarity as the frog, apparently there is no danger of a short occurring between the open blade and its stock rail as there is sufficient clearance for 009 wheels.

So, that is what I have done, frog is switched by a micro switch on the servo mounts and both frog rails have IRJs where they meet the track. 

The problems I subsequently encountered with a dead short were caused by the original track layer omitting the IRJs where they were required and actually putting one in the stock rail of point A. Quite naturally when I laid the new point at A I used a regular rail joiner hence the short. This has been corrected and all works fine.

The only other thing I am doing is adding a second micro switch to the servo mount so that the appropriate blade rail is only energised as the point closes. This will prevent the possibility of a short occurring if the first blade rail is still in contact with its stock rail but the micro switch has operated.

The attached photo and extracts from Peco documentation should help clarify why certain things were done in the beginning.

 

 

Edited February 5, 2022 by rynd2it
Clarification