Frog Switch for Copperclad Construction

[AndyID]

I've no idea if this is novel or not, but it's worked quite well for me in the past, so I thought others might be able to do something with it. It's cheap, simple and, in my experience, quite reliable, and it has the advantage that it's virtually impossible for the frog polarity to contradict the points setting.

 

Hopefully this photo is fairly self-explanatory, but please read the blurb after the photo for more details. (Looks like those timbers have endured a few derailments!)

 

 

A phosphor bronze contact strip is soldered on to an electrically isolated section in the middle of the tiebar. The contact strip is curved before soldering so that it maintains pressure on the timbers. The dents form the actual contact points. A gentle tap with a center punch over a piece of hardwood or aluminium is all it takes.

 

The frog end of the contact strip is resting on a piece of copper laminate that is also isolated from the running rails. That needs to be electrically connected to to the frog.

 

The two closely spaced slots on the other timber are very important. The slots need to be as narrow as possible (I use a jewelers saw). The electrically dead piece between the slots ensures that the contact is "break before make". Without that, both running rails would be shorted together while the points were changing.

 

As the copper is relatively soft, I am not sure this contact arrangement would last for thousands of cycles, but it will probably meet the needs of many. The wiping action is actually quite effective at breaking through any oxide buildup.

 

The piece of sheet metal at the back is 0.008" phosphor bronze sheet. I cut my own contacts from it with tinsnips. It's a LOT less expensive than buying pre-cut strips.

 

If you think it's a bit unsightly, you could always hide it under one of those ramps that were (I think) intended to protect tiebars from errant couplings. Alternatively, if you use double sided copperclad, you could mount the whole shooting match upside-down underneath the point, but that might lead to serious maintenance issues.

 

 

 

[Wibble]

It's novel I guess....... but why not just connect the tie-bar to a commercially available slide or toggle switch? You'll get change from a quid and have more time to think of other ideas.

[The Bigbee Line]

In the 1980s the smp plastic sleepers point kits had something very similar.

Good idea, but as Wibble said, I'd rather have a more robust slide or micro switch somewhere else in the drive.

But as they say. Your child always looks the nicest.

[AndyID]

[The Bigbee Line]

SHOW ME YOURS

 

When people become critics, (as I did in the previous post) especially at exhibitions a common response is:  "OK you say my layout

is crap, Show me yours....."  That usually sends them scurrying.

 

In that vein, here's one of my attempts at switching a Peco Code 83 turnout that I'd changed the point blades

with some filed from rail rather than the Peco pressed efforts:

 

 

The idea was to be able to operate the turnout from either side.  A wire runs right across the board. 

Copper tube provides the conduit for the wire.  The ends have a piece of copper tube pushed on

and the very end bent upwards at 90 degrees to provide a discrete operating thingy.

From one end a second wire takes the motion to the tiebar.  The copper tube has a subtle bend to

gain a few milimeters of elevation, doing so it adds enough friction to hold the tiebar in either direction.

The end of the second wire is also in a piece of copper tube, the end of this is bent at 90 degrees

alond the horizontal plane to provide the action for the microswitch

 

 

I liked the action and also the appearance of the new point blades.  If using this method I would prefer to have the switch and mechanism under the board, no need then to hide it in scenery...

 

 

The solid blades were very easy to fit.  Just take some code 83 from Peco flexi Code 83, files the blade to a suitable shape, remove the Peco blades and the section of rail back to the next joint, cut the switch rail to length, smooth the end and slide ito position.  I replace one tie (sleeper) with a copper clad substitute.  That transfers the power from the stock to the switch rail.  A fibreglass copperclad tiebar finishes the job.  That was done in 2008, never actually used them in anger, only test run.  Hopefully this year they will get used.....

[AndyID]

How long did that take? I think it took me about five minutes.

[chaz]

SHOW ME YOURS

 

When people become critics, (as I did in the previous post) especially at exhibitions a common response is:  "OK you say my layout

is crap, Show me yours....."  That usually sends them scurrying.

 

In that vein, here's one of my attempts at switching a Peco Code 83 turnout that I'd changed the point blades

with some filed from rail rather than the Peco pressed efforts:

 

1a1a 20080518 OMWB 003.jpg

 

The idea was to be able to operate the turnout from either side.  A wire runs right across the board. 

Copper tube provides the conduit for the wire.  The ends have a piece of copper tube pushed on

and the very end bent upwards at 90 degrees to provide a discrete operating thingy.

From one end a second wire takes the motion to the tiebar.  The copper tube has a subtle bend to

gain a few milimeters of elevation, doing so it adds enough friction to hold the tiebar in either direction.

The end of the second wire is also in a piece of copper tube, the end of this is bent at 90 degrees

alond the horizontal plane to provide the action for the microswitch

 

1a1a 20080518 OMWB 006.jpg

 

I liked the action and also the appearance of the new point blades.  If using this method I would prefer to have the switch and mechanism under the board, no need then to hide it in scenery...

 

1a1a 20080511 Peco Code 83 with solid blades 011.jpg

 

The solid blades were very easy to fit.  Just take some code 83 from Peco flexi Code 83, files the blade to a suitable shape, remove the Peco blades and the section of rail back to the next joint, cut the switch rail to length, smooth the end and slide ito position.  I replace one tie (sleeper) with a copper clad substitute.  That transfers the power from the stock to the switch rail.  A fibreglass copperclad tiebar finishes the job.  That was done in 2008, never actually used them in anger, only test run.  Hopefully this year they will get used.....

 

Looks much neater than Peco cut blades, however the soldered joints between your blades and the PCB tiebar are a weakness. As the tiebar moves the blades will try to pivot slightly as they move in an arc - over time this can cause the solder joint to fail, especially if a solenoid type point motor is used.

 

Chaz

[The Bigbee Line]

How long did that take? I think it took me about five minutes.

As a prototype, not quick, as your thinking about choices along the way.  Once past that stage quite quick.

 

The rodding is built as a kit of parts each part dome in multiple.  Each rodding run can be made and placed in about 5 minutes.

 

Fixing the switch about 1 minute, plus wiring, but that applies to any switch.

[AndyID]

There is another potential issue with using a microswitch. When you throw the switch, because there is no current flowing through the switch, the contacts may not "wet"  http://en.wikipedia.org/wiki/Wetting_current

 

A sliding contact eliminates that problem.

[AndyID]

Fixing the switch about 1 minute, plus wiring, but that applies to any switch.

Mine uses one wire, and it can be built right into the turnout if you want. How many does yours take?

[AndyID]

As the tiebar moves the blades will try to pivot slightly as they move in an arc - over time this can cause the solder joint to fail, especially if a solenoid type point motor is used.

Yes, that's a potential problem. I will be using slow-motion drive, so I should be OK. However, this works just as well if the blades are allowed to pivot at the tiebar. Another option is to make the entire blade assembly rigid and pivot it around a fulcrum closer to the frog.

[The Bigbee Line]

Mine uses one wire, and it can be built right into the turnout if you want. How many does yours take?

Mine uses a three wire system. I'm not expressing a preference as in terms of wires the hexfrog option will be used for long term DCC operation.

It's just that my latest small boards needs the plain DC option for testing, so I'll be using some form of wire in tube with micro switches under the board.

[AndyID]

Mine uses a three wire system. I'm not expressing a preference as in terms of wires the hexfrog option will be used for long term DCC operation.

It's just that my latest small boards needs the plain DC option for testing, so I'll be using some form of wire in tube with micro switches under the board.

 

If you plan to use DCC, you might consider abandoning live frogs altogether.

[Focalplane]

Good discussion, much needed.  The radial motion of the tie bar is an inherent problem, particularly where soldering is used.  I have some C&L tie bars which have a flexible insulated piece between the two brass sides (see their website for a very small picture.  I have yet to use them so have yet to work out the best way of fitting them, particularly on a double slip.  My single turnouts have copper clad tie bars, suitably gapped, and being B6 there is not too much stress on the soldered joints.  The double slip is a different story.

 

If you are using a slow motion drive, such as Tortoise, do you need a slide switch at all to change the polarity of the frog?

[The Bigbee Line]

If you plan to use DCC, you might consider abandoning live frogs altogether.

I have previously used a razor saw to introduce extra rail breaks to create the minimum sized dead frog, but still kept the metal rather than plastic crossing nose.  I made the dead part about 20mm long.  It's an option, but my personal preference is to maximise the potential pick up area.  Likewise if keeping the peco point blades I would ideally connect these with a very fine wire as they can occasionally lose their flow of current.

 

Some people are lucky and get away with much less.  I like to invest a little extra time at the construction stage to prevent a problem later.

 

Final note - If I was running multiple units of at least two coaches, with all wheel pick up, wired through all coaches I would say dead frogs would be fine.  Otherwise it's live frogs for me.

[The Bigbee Line]

Good discussion, much needed.  The radial motion of the tie bar is an inherent problem, particularly where soldering is used.  I have some C&L tie bars which have a flexible insulated piece between the two brass sides (see their website for a very small picture.  I have yet to use them so have yet to work out the best way of fitting them, particularly on a double slip.  My single turnouts have copper clad tie bars, suitably gapped, and being B6 there is not too much stress on the soldered joints.  The double slip is a different story.

 

If you are using a slow motion drive, such as Tortoise, do you need a slide switch at all to change the polarity of the frog?

The tortoise has two built in Single Pole switches.  Some DCC users use them in parallel to ease the current load in the event of a short.

[AndyID]

The tortoise has two built in Single Pole switches.  Some DCC users use them in parallel to ease the current load in the event of a short.

 

That's not really the problem. If you run into a live frog at the wrong polarity with DCC, you short out the entire feed, and that might mean the entire layout. It might be a lot simpler to revert to dead frogs and use DCC decoders that include "flywheel" capacitors that prevent stalling on dead frogs.

 

If you are going to have to wire up things like "frog juicers", you've just lost one of the major benefits of DCC - simple wiring.

[sp1]

If you plan to use DCC, you might consider abandoning live frogs altogether.

And if you're building the track yourself how do you incorporate dead frogs, and why would you want to?

[chaz]

Good discussion, much needed.  The radial motion of the tie bar is an inherent problem, particularly where soldering is used.  I have some C&L tie bars which have a flexible insulated piece between the two brass sides (see their website for a very small picture.  I have yet to use them so have yet to work out the best way of fitting them, particularly on a double slip.  My single turnouts have copper clad tie bars, suitably gapped, and being B6 there is not too much stress on the soldered joints.  The double slip is a different story.

 

If you are using a slow motion drive, such as Tortoise, do you need a slide switch at all to change the polarity of the frog?

 

Answer to your last question is no, of course not. The Tortoise has two changeover switches, either one of which will change the crossing polarity. At one stage I was using servos to operate points. These were driven with MERG driver PCBs which required a simple on/off switch. By using a DPDT switch I could wire one pole of the switch to control the servo, with the other one wired as a polarity changer.

 

On the question of tiebars I do have an acquaintance who makes his own points and puts very chunky insulated tiebars under the baseboard top. Vertical pins locate in holes in the tiebar and can pivot and will also flex slightly. They pass through in slots and their ends are formed in an "L", soldered to the underside of the blades. A purely cosmetic scale tiebar is fixed in view. A Rolls Royce solution?

 

Chaz

[AndyID]

And if you're building the track yourself how do you incorporate dead frogs, and why would you want to?

 

Presumably because you were using DCC  Mind you, leaving the frogs live could be a good driver training method to reduce the number of SPADs.

 

It's not terribly difficult to make an insulated frog with copperclad construction, but not something I prefer to do.

[AndyID]

A purely cosmetic scale tiebar is fixed in view. A Rolls Royce solution?

 

 

I've have seen that done too. It's very elegant and if he enjoys how it looks, then good for him. I'm afraid I'm too lazy to go to that sort of extreme - I prefer to bodge it by hiding everything under a ramp (and my eyesight is not anything like it used to be)

[chaz]

I might be being dim (it's not unusual) but why does the DC/DCC thing make any difference to whether the crossings are live or not?

 

My own preference (which I am slowly changing to) is DCC with every loco having a Keep-Alive (Stay-Alive, Powerpack etc etc); but even with these fitted I would opt for live crossings and pickups on as many wheels as possible. Belt and braces to eliminate any likelihood of a stall. Of course any point set against the route will result in a shut-down - regrettable but we are all human and errors are inevitable.

 

Chaz

[AndyID]

why does the DC/DCC thing make any difference to whether the crossings are live or not?

 

Ah! One of the unadvertised "features" of DCC.

 

On a DC layout with sections and multiple controllers, if you try to drive through a live-frog turnout that's set for the wrong road, you short circuit the controller and the locomotive stops. All the other sections powered by other controllers are unaffected.

 

On a DCC layout you will also cause a short circuit, and that takes down everything on the DCC feed, which might be the entire layout. That may not be too bad for a small layout with one operator, but you can see how it would be a huge problem on an exhibition layout. 

 

"What the heck just happened?!?!"

 

"Oh, it's Fred. He forgot to change the points, AGAIN!"

[The Bigbee Line]

Ah! One of the unadvertised "features" of DCC.

 

On a DC layout with sections and multiple controllers, if you try to drive through a live-frog turnout that's set for the wrong road, you short circuit the controller and the locomotive stops. All the other sections powered by other controllers are unaffected.

 

On a DCC layout you will also cause a short circuit, and that takes down everything on the DCC feed, which might be the entire layout. That may not be too bad for a small layout with one operator, but you can see how it would be a huge problem on an exhibition layout. 

 

"What the heck just happened?!?!"

 

"Oh, it's Fred. He forgot to change the points, AGAIN!"

A good case for the Hex Frog Juicer......... There is a danger that this thread will become a spiral.  There are plenty of different ways of doing things, people just need to choose for themselves...

[AndyID]

There is a danger that this thread will become a spiral. 

 

I thought it already had