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Modbury - Trackwork 4 (Turnout Operation)


Ian Smith

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Now that most of the trackwork has been installed on the first (Exeter end) baseboard, it is time to try it out!!!

 

Before I can though, a Turnout Operating Unit needed to be built. The first thing required is a method of connecting the Switch Rails to any under board gubbins. Obviously I had already thought all of this out up front, but I did need to open up the holes that I'd drilled to accommodate these fixings because I couldn't feed them down!! These first items were bent up from some 0.026" guitar string (ideal because being steel it is strong despite the small section, and also being nickel coated you can solder to it very easily).

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Guitar String Switch Rail Connectors (these were the rejects, the ones used are identical but have slightly less horizontal wire to run underneath the stock rails). The little loopy bend fits around the foot of the Flat Bottomed Switch Rail, the tail being soldered along the Switch Rail towards the heel)

 

The actual TOU is constructed from 2 sizes of Plastruct square tubing (one sliding within the other). Brass attachments (rod drilled 0.4mm in the lathe) allow the capture of the previously fitted guitar string switch connectors with minimal slop, but little friction and no stress on the soldered joint between the switch rail and the connector.

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Part for the TOU

 

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Made up TOU (subsequently, a hole was drilled to accept the moving wire from the Memory Wire Turnout Actuator, and once fitted a small micro switch was attached to switch the crossing polarity)

 

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What the TOU looks like from above the baseboard

 

For all of my turnouts and signals, I have decided to use Memory Wire actuators. These are built up on a piece of acrylic sheet (simply because I had some), and comprise a 5 volt regulator, a resistor in line with the actual memory wire, a pivot to allow transfer of the movement and a spring to return the wire to normal once the current is turned off.

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Made up Memory Wire actuator (I actually had to modify this one switching the memory wire and return spring over as I'd forgotten that it would be upside down when fitted to the board - doh!

 

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What it all looks like below baseboard

 

Below is a short video of the whole lot under test :

 

Regards,

 

Ian

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Well Ian,

 

It reminds me if that song......"Smooth Operator" (Sade)

Now you'll have to get a sound decoder rigged up to make the sound of the turnouts clanking as they move !

Seriously though, well thought out piece of work, well done.

 

Best

Grahame

(Currently still in deepest Kernow)

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I see in one of your brass attachment pieces the attachment hole is a slightly elongated hole, presumably for some adjustment?

 

Where did you get 0.026" solid guitar string from? - the largest solid I've encountered is 0.024".

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Well Ian, It reminds me if that song......"Smooth Operator" (Sade) Now you'll have to get a sound decoder rigged up to make the sound of the turnouts clanking as they move ! Seriously though, well thought out piece of work, well done. Best Grahame (Currently still in deepest Kernow)

Grahame,

I have seen others make their TOU's in the same fashion, I just added a memory wire actuator :-)

 

Fantastic. Only thing that needs mentioning is that the absence of a crew is very apparent in that engine...

Gareth,

I know!!  Before I fit a crew I need to make a backhead (and the injectors) - It's on my list of things to do (hopefully before the 2SA AGM), but there are only so many hours in the day even for a retiree :-)

 

 

I see in one of your brass attachment pieces the attachment hole is a slightly elongated hole, presumably for some adjustment?

 

Where did you get 0.026" solid guitar string from? - the largest solid I've encountered is 0.024".

Miss P,

You are quite right, one of the uprights has an elongated hole to allow for some adjustment - I should have mentioned that ;-) they are attached with 10BA bolts, one of which was left over long so that I could use it to act upon the micro switch for polarity switching of the crossing (ultimately I intend to build a lever frame, and will use a micro switch there to switch on the current to the memory wire).

You may be right, it might be 0.024" (although the bit sticking out of the end of my memory wire actuator is thicker than the switch connectors).  I bought a pack of 6 strings from e-bay, 3 solid, 3 wire wound.  If I remember tomorrow I'll check the make (and the thicknesses of the 3 solid wires).

 

Ian

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  • RMweb Gold

Great stuff Ian although the ability to be able to play trains is liable to slow progress!

 

jerry

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  • RMweb Gold

How's the action on the memory wire?  I ended up using a 1.5v AA battery on the sole memory wire turnout I've done so far as with higher voltages, the contraction was much quicker than the current-off expansion.  Going down to 1.5v equalised the movement speed.  I use a normal zinc-carbon battery, a rechargeable delivers too much current which permanently changes the wire...

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  • RMweb Gold

Very neat Ian. I hadn't thought of having the tubes to take the wires outsie of the stock rails. I have been experimenting with these things as part of the track tests I have been doing. The whole tou looks very neat and I see you have elongated one hole so can adjust the spacing of the tubes.

Don

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Great stuff Ian although the ability to be able to play trains is liable to slow progress!

 

jerry

Jerry,

Thank you.  Given that I've only got the one turnout in the 3' length that works at the minute I think that "playing trains" will get a bit boring after a couple of movements :-)

 

 

How's the action on the memory wire?  I ended up using a 1.5v AA battery on the sole memory wire turnout I've done so far as with higher voltages, the contraction was much quicker than the current-off expansion.  Going down to 1.5v equalised the movement speed.  I use a normal zinc-carbon battery, a rechargeable delivers too much current which permanently changes the wire...

Mark,

The action of the memory wire can be seen in the video I've attached.  The close up of the switches was edited in, and shows the movement in real time in both directions.  The "Normal" position of the switch is the straight through road (controlled by the spring), the movement to the curved road is actioned by the memory wire, so the first movement in the sequence is memory wire operated, the return movement is spring operated.  I had to beef up the spring after I'd built the unit as the return was considerably slower than the memory wire pull.  I have a power supply that I use in my other (Radio Controlled Car Racing) hobby that delivers over 13 volts (at up to 15 amps) for charging the battery packs, I intend to use this to power all of the actuators I will have and supply the juice for the controller too.  The single actuator draws about 0.3 amp while the memory wire is activated.

 

 

Very neat Ian. I hadn't thought of having the tubes to take the wires outsie of the stock rails. I have been experimenting with these things as part of the track tests I have been doing. The whole tou looks very neat and I see you have elongated one hole so can adjust the spacing of the tubes.

Don

Don,

Thank you.  I didn't even consider trying to put the tubes inside the switch/stock rails!!  I thought there would be too little room and I also needed the switch connector wire to lie beneath the stock rails to prevent them lifting with a loose heel switch.  Whether the elongated hole was strictly necessary I don't know as I could potentially have just angled the tube slightly but it seemed a better engineered way of doing it ;-)

 

Regards,

Ian

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Hi Ian, your trackwork and TOU look impressively neat!

 

Just one question occurs to me, not knowing too much about memory wire; what temperature is the wire at when the point is thrown to the sidings?

 

Best Regards, 

 

Chris.

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I see in one of your brass attachment pieces the attachment hole is a slightly elongated hole, presumably for some adjustment?

 

Where did you get 0.026" solid guitar string from? - the largest solid I've encountered is 0.024".

Miss P,

I made a mistake, the guitar string is actually .26mm not .026" (a B-2nd), the wire on the actuator is a G-3rd (0.016", 0.41mm).

 

 

Hi Ian, your trackwork and TOU look impressively neat!

 

Just one question occurs to me, not knowing too much about memory wire; what temperature is the wire at when the point is thrown to the sidings?

 

Best Regards, 

 

Chris.

Chris,

Thank you.  I've just checked the temperature of the memory wire (I have a temperature sensor that I use in RC Racing to ensure that I don't cook my motors by over-gearing) and after a couple of minutes it is at 34 degrees C.  The resistor is around 100, and the regulator a little less (so needs a heat sink really)

 

A couple of photos showing the area around this first working turnout now with the transoms in place (Plastruct 1mm x 1.5mm section) :

2FS Baulk Road Turnout (with Transoms) 2

2FS Baulk Road Turnout (with Transoms) 1

 
Ian
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Chris,

Thank you.  I've just checked the temperature of the memory wire (I have a temperature sensor that I use in RC Racing to ensure that I don't cook my motors by over-gearing) and after a couple of minutes it is at 34 degrees C.  The resistor is around 100, and the regulator a little less (so needs a heat sink really)

 

 

Are you worried that in a slightly warmish hall (Oxford 2010 for those who remember...), or on a hot day in your shed, all of your points are going to throw themselves without any current being applied?

 

Chris.

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Are you worried that in a slightly warmish hall (Oxford 2010 for those who remember...), or on a hot day in your shed, all of your points are going to throw themselves without any current being applied?

 

Chris.

Chris,

 

I hadn't really given any serious thought to it.  It would have to be uncomfortably warm at 30 odd degrees, and if it was that hot I don't think I would want to be in the shed anyway.  Perhaps an experiment holding one of my test actuators a little way over the spout of a kettle (central heating not on otherwise on top of a radiator) will show if it's likely to be an issue.  I'm more concerned about the temperatures the regulator and resistor are reaching - I will speak to John about it when I next see him.

 

Ian

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  • RMweb Gold

Ian I bent a piece of brass rod/wire to give one leg straight down a loop under the stock rail and a horizontal leg under the blade. That way the tube would be under the blade. I think there is a photo still on the camera.

Don

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Chris,

 

I hadn't really given any serious thought to it.  It would have to be uncomfortably warm at 30 odd degrees, and if it was that hot I don't think I would want to be in the shed anyway.  Perhaps an experiment holding one of my test actuators a little way over the spout of a kettle (central heating not on otherwise on top of a radiator) will show if it's likely to be an issue.  I'm more concerned about the temperatures the regulator and resistor are reaching - I will speak to John about it when I next see him.

 

Ian

 

Perhaps it's more an academical question then, as I appreciate that complex shunting moves aren't on my mind either when it gets that warm. I'd still be interested to know at what temp the wire starts to move though (i'm guessing its a bit lower than the 34oC quoted), and if it is sufficiently high not to pose a problem.

 

Chris.

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  • RMweb Gold

Those transoms look excellent, I'm sure IKB would be most impressed!

 

Dave

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Those transoms look excellent, I'm sure IKB would be most impressed!

 

Dave

Dave,

Thank you.  They're taking a little time to cut exactly to size and fit, but I think that it has really made the difference - It's starting to look like Brunel's Baulk Road now!!  

 

I want to find something fine for the ash ballast after they're all in, on my test track I've experimented with DAS modelling clay pressed into place and stippled with a decorating brush - the effect is quite nice and the white stuff I've used accepts well watered down water colour paint allowing a depth of colour to be built up by adding successive coats of black/grey/brown.

 

Ian

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  • RMweb Gold

Hi Ian,

 

I'm coming late to this but wonderful to see things moving on your baulk road. Turnouts and loco both! As Dave says, with the transoms in place it's really looking the part now.

 

Regarding crews in locos: Will you make their heads turn when running bunker first? Should be a doddle for someone like you! :-)

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Hi Ian,

 

I'm coming late to this but wonderful to see things moving on your baulk road. Turnouts and loco both! As Dave says, with the transoms in place it's really looking the part now.

 

Regarding crews in locos: Will you make their heads turn when running bunker first? Should be a doddle for someone like you! :-)

Mikkel,

Thank you for the positive comments.  I hadn't really thought about making the crew heads rotate - I was putting all of my energy into getting the fireman's arms to shovel coal :-)

 

Seriously though, just to get a crew in there would be good - although I'm currently giving the track work a rest for a couple of days while I try to get another loco chassis up and running.  This time for a Small Metro tank, obviously in 2mm weight is key (to aid both traction and pickup) so I'm trying to mill out a solid brass chassis (albeit split frame).  Another blog entry is probably on the horizon for this :-)

 

Regards,

 

Ian

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