Under bed OO Thomas the Tank Engine layout?

[Fold]

I am following this (mostly!), thanks for everyone's input. There still seems to be a wide variety of opinions which is a little worrying.  Apart from the 230v > 12v > 12v > 230v potential catastrophe (and I say that not to diminish it), what are the actual consequences of powering the same bit of track with two controllers on the running of trains or the trains themselves?

 

If I can attempt to boil down the varying options into 3 broad categories:

 

1. @BroadLeaves plan, which maximises flexibility of routes but, if I understand correctly, still might have the possibility of powering the same bit of track under certain configurations. Actually, I'm not sure anyone has explicitly come out and said this, but there certainly seems to be an implication this could happen?
2. Something with breaks at both crossovers, which eliminates all possibility of powering the same track but means a crossing train needs synced/swapped controllers, so it's less flexible. I also imagine there is an outside risk of causing a big crash and/or engine damage from one loop being set to forward and the other reverse, and the engine being driven across?  I'll call this the @RJS1977 plan.
3. Something with more advanced switches and wiring such as described by @Chimer - best of both worlds (flexible routes and no chance of powering the same track) but at the cost of needing wiring and soldering. BroadLeaves is right I am very keen to avoid this as (if you couldn't tell) I have no idea what I'm doing and it means I'll probably not be able to use the kit I already have.

I am erring towards option 2. I think syncing controllers is a pretty simple operation to teach them.  It also keeps things neat - the bottom controller is for the inside, the top one for the outside. 

 

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On 25/01/2022 at 10:19, Andy Hayter said:

A dust cover may well help but it may make some items on the layout vulnerable to being damaged as the cover is placed and removed.  

 

With  2 and 4 year old the layout has bigger issues to contend with than a dust sheet. Everything is going to need to be very robust or very cheap and easy to replace!

 

On 25/01/2022 at 17:57, RJS1977 said:

Before we go too much further with the wiring - I'd suggest reversing the left hand siding so that the point is at the top of the board rather than the bottom. This is because as drawn, a train proceeding around the outer loop in an anti-clockwise direction will go straight into the siding and the loco will be trapped at the wrong end. Reversing the siding means the train will set back into it, then the loco can be uncoupled and go off and do something else.

 

The right hand siding (with the kickback) should stay as it is.

 

Two other advantages of this are:

 

1)  Apart from the crossover by the blue arrow, all the points are on one side of the baseboard (so easier to reach).

2)   This removes the need for the point clips at the bottom of the plan.

 

Thanks for the ideas but like BroadLeaves I struggle to see the difference - whichever way I put it, unless trains reverse in they will end up with with the loco at the wrong end.  The boys will also have 360 degree access to the board and adding some point clips seems pretty trivial, so I'll keep the layout as is.

 

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While the debate on the best electrical setup rages, I'm making progress on the simpler stuff.  In my hobby I'm notorious for planning projects and never starting them or starting them incredibly slowly. I'm keen to avoid this fate and so I've been ordering materials left right and centre and plowing in to construction. The base board is cut and construction of the framing is well underway.  

 

I made a simple maquette to get it clear in my head where I would need to raise/lower the underlying framing and cut the base board to achieve the contours.

 

 

 

And today me and the boys tested out Thomas and Percy on varying gradients, up, down, forwards and reverse, with varying train lengths.  Happily it seems these little engines are on the powerful end of the spectrum and I won't have to worry about gradients as some of you have warned about. Percy was comfortable at 7% and topped out at 8% (just about making it to the top but with plenty of wheel spin). For his part, Thomas managed a mighty 16% while pulling the mail truck and two wagons. In reality, 7% is more than enough for me as it would allow a theoretical 7cm rise from the lowest point (north side of the board) to the south side , and then another 10cm again to the raised goods yard. And I don't actually have that much space under the bed once the depth of the baseboard, framework and castors is accounted for. I'll probably go with something like 3% and 5%, for a ~10cm total rise. This will be more than enough for the planned road tunnel under the goods yard too, without needing to notch out the frame below.

 

 

 

[ITG]

8 hours ago, Fold said:

There still seems to be a wide variety of opinions which is a little worrying.  Apart from the 230v > 12v > 12v > 230v potential catastrophe (and I say that not to diminish it), what are the actual consequences of powering the same bit of track with two controllers on the running of trains or the trains themselves?

My suggestion would be to pose this specific question in the 12v DC section in the Power section of this forum. There’s a chance those best placed to clarify the implications may not have seen this thread, placed in Layout Design. As I said, I run DCC so am I in a different place,  but as a basic electrical theory, it just seems wrong to have two controllers, each throwing out 12v, overlapping, and the locos having to contend with that.

Good luck.

[Kris]

8 hours ago, Fold said:

 

 

Looks like Thomas is about to take off  Testing the gradients in advance to make sure that they work for you was a very sensible thing to do. 

[Chimer]

9 hours ago, Fold said:

 

Something with more advanced switches and wiring such as described by @Chimer - best of both worlds (flexible routes and no chance of powering the same track) but at the cost of needing wiring and soldering. BroadLeaves is right I am very keen to avoid this as (if you couldn't tell) I have no idea what I'm doing and it means I'll probably not be able to use the kit I already have.

 

 

Well, you can't do without wire (you just need 8 more bits of it), there's no need for any solder (you can twist wire onto the switch tags), and all the kit you've got will work just fine.

 

But the gradients would make me nervous - I would suggest that before you start butchering the board, you put the tracks together on the flat first, operate it that way, and when you're happy that everything works and delivers enough fun, then decide if the gradients are a must.  The plywood won't flex the way the paper does when you try to raise one end of a curved section .... 

 

Best of luck, whatever way you go!

[BroadLeaves]

11 hours ago, Fold said:

And I don't actually have that much space under the bed once the depth of the baseboard, framework and castors is accounted for

Don't forget to also include the height of the buildings and scenery such as trees.

[Fold]

3 hours ago, Chimer said:

 

Well, you can't do without wire (you just need 8 more bits of it), there's no need for any solder (you can twist wire onto the switch tags), and all the kit you've got will work just fine.

 

But the gradients would make me nervous - I would suggest that before you start butchering the board, you put the tracks together on the flat first, operate it that way, and when you're happy that everything works and delivers enough fun, then decide if the gradients are a must.  The plywood won't flex the way the paper does when you try to raise one end of a curved section .... 

 

Best of luck, whatever way you go!

Kris used 12mm OSB to achieve a similar effect on his layout and I’ve dropped down to 9mm ply. I’m quietly confident but will certainly be following a rigid order - flat layout first and lots of testing. Then trace the track layout and from this deduce the necessary holesaw and jigsaw cuts. The actual bits being bent will be relatively narrow, which helps. I shall then begin the bending systematically working around the board but if it doesn’t work there is no reason I couldn’t get a thinner sheet of ply or just revert to flat again.  Assuming it does work, the track will then be screwed down. Looking forward to it - I admit most of the motivation for varying elevation is to maintain my own interest and give me a building challenge, but I do think the boys will appreciate some hills too.

 

2 hours ago, BroadLeaves said:

Don't forget to also include the height of the buildings and scenery such as trees.

 

Indeed. Many of these will have to be removable - the aforementioned drawers built into the frame can hold some of this (trees) once removed and the rest will just have to be placed on the lowest part of the board during downtime.

[JDW]

Without wanting to confuse the issus, I have to admit I was reading through all the electrical talk over the last few pages, and I'm glad someone else asked the question about isolating rail joiners. For many years my "train set" when I was young had two tracks with crossovers, and I never had a problem with not using isolating rail joiners. I simply set one controller to off, switched the points and drove a train from one side to the other. No damage was ever caused to either controller, nor to the trains, and it was much more user-friendly than driving a bit on to the other circuit, stopping, changing controller, changing the points... I quickly figured out that by setting both controllers to a similar speed, I could quickly switch the points back to straight and the train would just carry on around the other circuit. 

I'm not saying that the approach above is a bad one, and I can't comment on the actual risk of getting a shock from an unplugged controller's plug (easy to solve, always plug in both), but I wonder if we're trying to over-complicate things. In real terms, I'd go as far as saying that trying to fit isolating joiners adds more problems than it solves. 

[Zomboid]

Back feeding the second transformer seems very unlikely. I don't know what ever controller contains, but the simplest design would be a 230/16V transformer then a diode bridge rectifier and a variable resistor. There might be other bits around it, but the basics will be something like that. The rectifier element will prevent back feeding the transformer.

 

Or am I missing something?

[RJS1977]

29 minutes ago, JDW said:

Without wanting to confuse the issus, I have to admit I was reading through all the electrical talk over the last few pages, and I'm glad someone else asked the question about isolating rail joiners. For many years my "train set" when I was young had two tracks with crossovers, and I never had a problem with not using isolating rail joiners. I simply set one controller to off, switched the points and drove a train from one side to the other. No damage was ever caused to either controller, nor to the trains, and it was much more user-friendly than driving a bit on to the other circuit, stopping, changing controller, changing the points... I quickly figured out that by setting both controllers to a similar speed, I could quickly switch the points back to straight and the train would just carry on around the other circuit. 

I'm not saying that the approach above is a bad one, and I can't comment on the actual risk of getting a shock from an unplugged controller's plug (easy to solve, always plug in both), but I wonder if we're trying to over-complicate things. In real terms, I'd go as far as saying that trying to fit isolating joiners adds more problems than it solves. 

 

I think the real problem is that if one child is driving a train on one oval, and the other is driving a train on the other, then if one of the crossovers is accidentally 'half set', the child driving the train on the outer loop can inadvertently also be controlling the one on the inner loop or vice versa.

[JDW]

I'm not sure I'd class that as a "real problem", either they'll notice the other move, stop and change the points, or the train will go round onto the other track and they'll stop or carry on. WIth the points set like that they won't get more than a lap anyway. I'm not sure I'd count it as a problem in the grand scheme of things, a very minor 'oops try again' at worst.

[St Enodoc]

3 hours ago, RJS1977 said:

 

I think the real problem is that if one child is driving a train on one oval, and the other is driving a train on the other, then if one of the crossovers is accidentally 'half set', the child driving the train on the outer loop can inadvertently also be controlling the one on the inner loop or vice versa.

Only until they crash into each other.

[Fold]

Hello everyone

 

I just wanted to update progress here for anyone interested. Thanks to all your help things have progressed fairly quickly (by my normal hobby standards at least!) and we now have a finished contoured baseboard and today I anticipate finishing all the cork underlay.

 

I'm  happy to report that aside from a small adverse camber issue (location circled in red) that was causing carriages to tip off at high speeds the rails and trains work absolutely fine over the contoured board and as for the contouring itself it was very easy to do with 9mm ply even over these quite aggressive gradients. As you can see from the image, I started with large (3/4") holes at the transition points which give the wood a lot of leeway to bend without risk of splitting.

 

 

Once screwed down to the frame wherever the board needed to be flat, I then flipped the board over and screwed in "risers" wherever they were needed for stability, spaced out across the gradients. In this way I let the plywood dictate the curve it would take between the high and low points and simply reinforced it as necessary meaning all parts of the board are strong enough to be walked over.

 

The adverse camber issue has since been fixed by forcing the riser underneath to correct the angle, and applying an extra layer of cork below the track which was angled with sandpaper to create an opposite camber (these "cambering" layers of cork are shown here before and after being sanded down - and in the middle of being hoovered!)

 

 

From an electrical perspective with apologies to @BroadLeaves I have decided to insulate the loops entirely with insulated joiners at both crossovers, at the cost of some flexibility. In the end I just did a few tests of what happens when you power a rail with both controllers and what happens is the controllers cut out and you have to give them some "down time" before they'll work again. This also happens sometimes when trains crash or derail so I assume this is some sort of built in "trip" feature in the controllers.  Anyway, I am keen to minimise this down time as much as possible as it leads to loss of interest from the boys, hence the decision to fully isolate the loops.

 

The next steps are to complete the underlay (which are just 35mm wide strips roughly cut from 1.5mm A4 cork sheet) and then ballast along the edges of these strips only, with cork I have ground up to a fine rubble in a blender.  This is my compromise between leaving the simple cork strips as is, and a proper ballast job filled in between the sleepers. The former being functional but not really satisfying the modelling itch, and the latter being scenically perfect but  which requires applying lots of glue up to the rails and around the sleepers which in my head risks electrical connectivity issues and makes it much harder to alter the layout in the future (and affects any resale value the track has). Once the cork is secured we will paint the cork and do a basic paint layer over the rest of the board so it at least isn't bare wood until we get around to the more advanced scenery.

 

[BroadLeaves]

19 minutes ago, Fold said:

with apologies to @BroadLeaves I have decided to insulate the loops entirely with insulated joiners at both crossovers

No need to apologise at all! If you have a layout that works for you and the boys, then that's the right outcome. 

 

20 minutes ago, Fold said:

Anyway, I am keen to minimise this down time as much as possible as it leads to loss of interest from the boys, hence the decision to fully isolate the loops.

Makes perfect sense to me.

 

23 minutes ago, Fold said:

applying lots of glue up to the rails and around the sleepers which in my head risks electrical connectivity issues and makes it much harder to alter the layout in the future (and affects any resale value the track has)

Dried glue won't be conductive, but I can certainly envisage layout changes as the boys grow up, so this also makes sense.

[Chimer]

As you may recall, I had my doubts about the gradients ..... and I am absolutely delighted to have been proved wrong!

[JDW]

Looking good. Great solution to the adverse camber problem. Just one question regarding the controllers tripping out if the track is fed from both - and with apologies if it's obvious - but they are both the same way around aren't they? As in if the inner rail on one circuit is positive and the outer rail negative, the other circuit is the same?

[RJS1977]

24 minutes ago, JDW said:

Looking good. Great solution to the adverse camber problem. Just one question regarding the controllers tripping out if the track is fed from both - and with apologies if it's obvious - but they are both the same way around aren't they? As in if the inner rail on one circuit is positive and the outer rail negative, the other circuit is the same?

 

That shouldn't cause a short unless both controllers use the same transformer winding.

[JDW]

I thought the cut out problem was when the crossover was set for going from one loop to the other ('power one rail with both controllers') not causing a short when the points were set to 'normal'. If one controller were trying to make a train go one way, and the other trying to make it go the other...

[Kris]

Great to see that it is all working for you. 

[Fold]

1 hour ago, JDW said:

I thought the cut out problem was when the crossover was set for going from one loop to the other ('power one rail with both controllers') not causing a short when the points were set to 'normal'. If one controller were trying to make a train go one way, and the other trying to make it go the other...

 

I experimented with all eventualities and don't remember what precisely caused the short. But the boys are 2 and 4 so anything can and will happen. And these controllers seem very susceptible to shorting which is a real shame and the biggest issue I have with the whole setup really.

[Chimer]

To be fair, the options are basically short out or burn out .........