Simple Point Control by Rodding

[berryr99]

Good maorning,

My new, portable, layout - Blaenau North - will only have 4 points.

I've decided to control the points by rodding underneath the layout.

Using a system I have made before the rods will consist of wire coat hangers with a 90 degree bend at either end - one end to engage with the point tie bar and the other end to make a simple lever to move the rod. The mechanism will be supported by cable clips (U shaped clips with a nail on one side - use them to secure telephone wires as well) placed under the baseboard.

I will also incorporate a sliding polarity switch on the rod itself

This seems a simple solution - the question is - am I missing anything ?

Any comments would be gratefully received

Thanks

Bob

[MickT]

Hi Bob,

Sounds like a good concept overall, but unless I have missed something obvious, I can't quite see how the right angle bend on the coat hanger at the point end, being quite a thick profile is going to connect to the point tiebar, unless you are going to secure a much thinner piece of something like piano wire to it to make the actual connection with the tiebar?

Mick

[tedp]

Hello Bob

I have done something similar, but using bicycle spokes and mains electricity terminal blocks.

Here is a diagram of the basic principle:



The spoke passes through the baseboard edge (right) and through another bearing (left). I have improved the principle by fitting better bearings for the spoke. On the left in the diagram I have installed a piece of mains terminal block (the nylon strip with brass connecting terninals inside) through which the spoke runs. Using the brass terminal block inside the nylon strip, I made a runner that can be clamped tight on to the spoke. To this I soldered a piece of thin steel wire as a dropper, or alternatively a pin pointing up through the baseboard. Fit two stopper clamps to the spoke so it has a limited stroke. That will guard against over-stressing the point tiebar.

You can also clamp the piece of steel wire inside the brass terminal piece to extend the movement to signals etc. like I have done in the example shown below.



Using the terminal blocks at the end makes for a very reliable bearing and the spokes hardly needed ajustment during the 10 years they have been used. Instead of using the end knob on the spoke to operate the point, you can connect itm up to a lever frame of the type produced by GEM. Instead of switching the frog of the point using two wire strips as shown in the diagram, you can work a normal switch or perhaps a microswitch from the spoke as well.

More info on the Dutch Group website.

[berryr99]

Mick - as I said it will be simple so I will file the coathangar down to a fine point where it is required to connect to the tie bar

Ted - this is interesting and I will have a think about this method

Bob

[Frank]

I have tried a similar system with coat hanger rods under the baseboard and microswitches for the polarity switching.

However I drilled a vertical hole in the baseboard for a short brass rod rotating inside a brass tube, with a small crank soldered to the top of the rod to work the point and a larger crank at the bottom, soldered to a brass inner from an electrical terminal block, to connect to the coat hanger.   Using the brass inner allows some adjustment of the height and angle, and the crank can then be secured to the rod with the screws in the terminal block.

Using this system, the rodding can run in any direction, it does not have to be at a right angle to the track.

The bottom crank is longer than the top one so the coat hanger moves a lot more than the point throw.  This seemed to make it easier to set up.

The mechanical control of the point worked fine.   The main difficulty I had was setting up the microswitch to switch reliably.

Frank

[berryr99]

Frank

That's helpful and I need to think about this method too.

Please can I ask what the issues with the Microswitch were ? I have bought a couple from Maplins to try out

Regards

Bob

[Frank]

Bob,

The issue with the microswitch was as follows:

I had the type of microswitch with a springy steel actuating arm attached.   I thought that setting this up so the rod pushed it as it changed the points would not be precise enough, so I decided to arrange it so the bottom crank actuated the arm as it turned, like a cam.   This way it was possible to have the switch change over in mid-stroke and so be definitely switched over by the time the points have changed.   

In the event the setting was too sensitive and the microswitches have kept going out of adjustment.   It would have been better just to have the rod push them I think.   If you position them more or less in the middle of the stroke and let the springiness in the arm take up the slack it should be OK.

Otherwise it's a good system.

Frank

[tedp]

For switching purposes I use another mains terminal screw block. I solder a brass pin to it, then position it on the operating rod so it hits the microswitch lever at the end of the operating stroke. That way you can fine tune the switching action any way you like.

[theelliotts]

I use a miniature toggle switch to change the frog polarity. Mounted on the outside of the baseboard and linked to the rod by a wire loop it acts to operate the turnout too.

David
Victoria BC Canada

[berryr99]

Hi David,

Does that mean the toggle switch has a direct connection to the tie rod itself ?

I can see how a wire loop can pull the rod one way (towards you) but how does it work for pushing the rod away....or have I misunderstood ?

Thanks

Regards

Bob

[tedp]

Wire in tube can push as well as pull. The solution with a slide switch or a toggle switch above baseboard and a wire loop is another simple control method, but you need a tube to get the movement to the point blades. I use a similar method but below baseboard, to reach beyond some of the operating rods.

[B.Meldon]

I have been re-building and finishing a layout started by the late Roy Watson in the 1970

[berryr99]

Brian,

Again its one of those "doh " moments - I wish I had thought of that. The problem with wire coathangers is that the maximum useable length is only about a foot  because of the bends in them, using a piece of rail would get over that.

Just to clarify on the switching, the SPST switch is connected back to the points/power by a set of wires ? I wasn't sure if you meant the rail rodding carried some of the switching ?

I find the polarity subject hard to understand so if you could just clarify that would be helpful

Thanks

Bob

[tedp]

The point blades do their own switching, but if you want a backup, you need to copy that with the switch. You connect the switch with three wires to the track close to the point (better not to solder to the point itself, as it says in the diagram - you might disturb the track gauge). The push/pull rod doesn't carry any current as it is connected to the plastic tie bar.

[B.Meldon]

Ted has clarified where the wires need to go.

The reason I, and many others, fit frog polarity switches on every layout is that I have found the electrical switching in the points, that is often just the blade pressing against the fixed rail is not reliable enough.

Personally I would use wires to take the switched feeds back to the track from  switch as I have now done on this layout.
However in the 70