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A 2mm loco service point


StuartM

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I noticed in the competition blurb that originality was one of the criteria and as there is nothing oridginal about a small diesel depot diorama, I thought I'd try and improve on that by making my own track in 2mm scale as this allows for tighter and more complex point work than can be achieved using standard Peco points. The photo's show a mock up of what I had in mind. I might keep with the full length depot in the photos or I might make one half the size, either way the depot will butt up against a mirror on the side wall to double the visual size without impacting on the 20x11" footprint.

Nothing is set in stone at the moment and I might well change my mind completely as this idea evolves.

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Self build, made from corrugated plasticard and 0.5mm brass for the hand rails, then painted in shades of grey, dry brushed with black.

The fueling points are Whiteknight kits which have been painted grey but still require weathering

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I joined the 2mmscale association about 6 months ago because I wanted to learn how to make my own track and the photos below show my first real attempt at some serious trackwork.

Although this piece of trackwork is "ok" it's not as good as I'd have liked, so I consigned it to the bits box while I started on the mkII.

When this competition was announced I thought I'd retrieve it and use it for the diorama plus it would give me the opportunity to wire it up in order to see how I was going to wire the mkII.

I strongly believe that if you want to make something, you need to make it twice, the first time to see how it should be done and the second time to actually make it.

Now it's in place I can build the remaining track around it.

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The wiring will be OK, the trackwork is split into 12 electrical sections which will be controlled by a small circuit which I'll build later.

Because this is my first attempt I've made loads of mistakes which won't be repeated on the mkII.

The mistakes are....

1. Don't cut the isolation breaks until the trackwork is glued into it's final position, otherwise it loses some of it's structural integrity

2. Solder the dropper wires on during the construction process rarther than afterwards, that way lengths of rail don't shift, also when soldering from the underside, solder runs downhill so ends up filling the gaps between rails, which is a complete pain to sand out

3. Don't make the joggles to pronounced

4. Make the isolation gaps in the sleepers before you solder rail to them.

5. Some of the gaps through the diamond are unequal

 

All in all it's not a bad attempt, it could just be a bit neater and there's a slight wobble or two when running a test truck over it, and the whole purpose of making your own track (for me anyway) is to have dead flat smooth running.

Although it might not be good enough for the mainline hopefully it will be alright for a diesel depot and then eventually when the competition is over I'm thinking of adding some additional boards either end and converting it to a shunting plank.

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Well for a first attempt that is VERY impressive!

 

When I first saw the plot of the track I thought to myself it was a little OTT for a small depot but now seeing the trackwork I can totally understand why you have done it. I hope you are proud of that track bacuase I definately would be.

 

Missy :yes:

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Thanks for the encouragement, having checked out your sites that is praise indeed.

I notice your based in wallingfordshire, I used to live in the next stop up the line Goring&Streatley,

I spent many a happy day as a lad down at the station watching Westerns et al go by

If only I had a time machine,

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  • RMweb Gold

I agree with Missy that is very impressive trackwork. I note one tiebar is missing or have you tried connecting the blades below the baseboard.If so it looks neater. Wiring the beast will be fun. One problem is the diamond as the polarity of most of it is decided by the setting of the two entry/exit points. If both are set to cross the diamond you would have a conflicting route. These should be interlocked in some way to avoid setting up conflicting routes that will probably determine how the diamond is set. The two slips are much simpler. The wiring would be simpler in DCC but if you opt for two controllers in DC you have extra switching for the feeds to think about. I shall be interested in the solution you adopt.

I like the depot too. The handrails look really good.

 

I used to cycle out to Goring/Streatly and Wallingford in steam days and then call in at Pendon. There was also an amusment with my Grandparents and a bull in the field down by the river (probably built over these days).

Don

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Tie bars will be replaced with droppers hence the holes beneath the rails at the end of the switch blades and the reason one tie bar is missing as I've already been playing around with that Idea.

I'm going to use this as my first foray into dcc as I thought a diesel depot with sound would add to the operational enjoyment, so the wiring will be simple enough,

I'm going to start designing the circuit that will be used to switch the power around between sections later today, diagrams and photos to follow as I progress.

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The diagram below shows where the isolation cuts have been made.

The track is split into 12 separate isolated sections.

The table below shows which sections need to be joined together to be able to get a train from from one point to another

ROUTE POLARITY SECTIONS

A-B + 1,4

A-B - 5,2,3

A-C + 1

A-C - 5,2,3,4

A-F + 1,2,7,8,12

A-F - 5,6,10,11

 

D-E + 9,10,8

D-E - 11,12

D-F + 9,8,10,12

D-F - 11

D-C + 1,2,6,9

D-C - 3,4,7,10,11

 

Because I'm going to use dcc rather than dc, this makes the control circuit a bit simpler because sections 1,8,9 are always on positive and sections 3,5,11 are always on negative, this only leaves sections 2,4,6,7,10,12 that require switching from positive to negative depending on which route has been set

Now I have this information I can start designing the control circuit, wiring diagram to follow

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  • 2 weeks later...

It's been a couple of weeks since my last post but I've been busy replacing the pcb sleeper tie/stretcher bars with wire in a tube as this is more realistic and is the preferred method for point control within the 2mm fraternity. The wire tubes are attached to a servo motor under the base board which operates the switch blades. This is the first time I've done this and it is a bit of a faff but that's probably because I had to attach wire to switch blades that were in situ, whereas next time I'm going to solder the wire to the blade before its been fixed in place as I reckon this will be a million times easier (we shall see) .

I took a an old signal control circuit that had been withdrawn from service and was sitting in the scrap line waiting to be cannibalised for parts and passed it over to the R&D dept (me) who were able to modify the circuit and reprogram the chip so the circuit could be used as the servo tester which is quite handy as each servo is controlled from an output port on a chip that requires it's own line of code with values specific for that servo. This meant I was able to test and set up each servo and make sure they all did what I wanted them to do.

I'm away to the mainland for some training in a weeks time, so I'm going to design the control circuit while I'm away, so this next week will be spent on the rest of the track.

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You can make the wiring of a crossing like this simple if you work to the rule that only 3 states are possible - all points set straight, left to right crossover set with other two points straight and finally right to left crossover set with other two points straight.

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  • RMweb Gold

You can make the wiring of a crossing like this simple if you work to the rule that only 3 states are possible - all points set straight, left to right crossover set with other two points straight and finally right to left crossover set with other two points straight.

 

That sounds a little restrictive. If we consider the 4 roads as ABCD any road needs to be able to arrive/depart. This will determine the setting of the crossovers. For A or B arrive and C or D depart the crossover will be normal. Entry and exit moves can be concurrent. For A or B depart or C and D arrive the crossover will be reversed. Concurrent entry and exit is not possible. So I conclude the following states are practical;

1. A arrive C depart

2. A arrice D depart

3. B arrive C depart

4. B arrive D depart

5. A depart or C arrive both set

6. B depart or D arrive both set

 

I will be interested to see Stuarts approach

 

Don

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  • RMweb Gold

You can make the wiring of a crossing like this simple if you work to the rule that only 3 states are possible - all points set straight, left to right crossover set with other two points straight and finally right to left crossover set with other two points straight.

 

That sounds a little restrictive. If we consider the 4 roads as ABCD any road needs to be able to arrive/depart. This will determine the setting of the crossovers. For A or B arrive and C or D depart the crossover will be normal. Entry and exit moves can be concurrent. For A or B depart or C and D arrive the crossover will be reversed. Concurrent entry and exit is not possible. So I conclude the following states are practical;

1. A arrive C depart

2. A arrice D depart

3. B arrive C depart

4. B arrive D depart

5. A depart or C arrive both set

6. B depart or D arrive both set

 

I will be interested to see Stuarts approach

 

Don

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When I first made this piece of track the idea was that it would be situated within a double oval at a station throat with two centre through roads and two loops leading into platforms.

Had that been the case most movements would be A>B & A >C on one road, and E>D & F>D on the other so in effect it would just be two ovals with a turnout in each, joined together by a diamond crossing.

Because each section is isolated from every other section, the two ovals although joined by the diamond are separated by the circuit which I was going to design to control the switching.

In addition to these movements it would have also been possible to go from A>F and from C>E which were going to be bay platforms. Again because all sections of the sissorslip are isolated not only from each other but also from the main ovals this is not a problem because again the control circuit switch's the power to the relevant section of track, although when one of "these" particular movements is taking place only one train can cross the trackwork at anyone time, which is how it would be in real life because one train would be crossing over another track.

However.......

In the case of this diorama, although all of the above applies electrically, because its only a small depot, it will only be practical for one locomotive to be moving at anyone time, even with dcc control.

I hope the clarify's the situation.

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Well for a first attempt that is VERY impressive!

 

When I first saw the plot of the track I thought to myself it was a little OTT for a small depot but now seeing the trackwork I can totally understand why you have done it. I hope you are proud of that track bacuase I definately would be.

 

Missy :yes:

 

 

Complete and utter "DITTO" !!!

 

Looking very impressive indeed !!

 

JB.

 

 

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That sounds a little restrictive. If we consider the 4 roads as ABCD any road needs to be able to arrive/depart. This will determine the setting of the crossovers. For A or B arrive and C or D depart the crossover will be normal. Entry and exit moves can be concurrent. For A or B depart or C and D arrive the crossover will be reversed. Concurrent entry and exit is not possible. So I conclude the following states are practical;

1. A arrive C depart

2. A arrice D depart

3. B arrive C depart

4. B arrive D depart

5. A depart or C arrive both set

6. B depart or D arrive both set

 

I will be interested to see Stuarts approach

 

Don

 

My comment specifically applied to the crossing. I was simply trying to pass on my experience that the logic of the wiring is much easier to sort out if you make it impossible for both crossovers to be set at the same time. The extra slips at one end of the formation don't change that, as far as I can see.

 

In reality you would not be able to run a loco both ways across the diamond of a scissors crossing at the same time anyway - at least not without a collision, so arranging the options in the way I described seems a reasonable enough solution to me.

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  • RMweb Gold

That sounds a little restrictive. If we consider the 4 roads as ABCD any road needs to be able to arrive/depart. T

Looking at the picture above, it appears the inner roads (your B and C) cannot use the crossover as the slips are only singles, on the outside. Wouldn't you'd need double slips for all roads to access both arrival and departure tracks?

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