Is the heat causing issues?

[WIMorrison]

I am finding several strange shirts and other control aspects happing on my layout and they are all down to the continued heat as seperation gaps between blocks close up which then confuses the feedback systems and shorts caused when points are set the wrong way.

 

Very frustrating as I know if I make the gaps large enough to cope with the current heat I will have large gaps in the winter

 

Any ideas on how to get around this - air conditioning isn’t an option

[RFS]

I had this problem the first time I built a layout in my converted loft.  Despite the conversion providing windows and ventilation, it still can get quite hot as indeed it is today. I assume that, like me, you are using plastic flexible track with insulation gaps just cut where needed. This is what caused me a problem in hot weather: occasionally a gap would close leading to an unexplained short.

 

When I rebuilt the layout to my current plan, I made the decision to always use insulated rail joiners (IRJs). These not only hold the track in proper alignment, but also have a plastic stub in the middle to prevent the two rails closing up.  Not had a problem since. 

[WIMorrison]

That would possibly be the issue - I don’t fancy ripping everything up though to insert little bits of plastic

 

Might need to think of an alternative method of achieving the objective

[peach james]

Glue plastic into the gaps when the layout is cold...

 

James

[WIMorrison]

Anyone have a spare air-cooling unit - otherwise it’s a long wait for it to cool down and for the rails to contract again

[RFS]

Glue plastic into the gaps when the layout is cold...

 

James

 

But if you do, make sure you have adequate expansion gaps elsewhere. Otherwise, the next time the railway room gets really hot, the track might decide to expand sideways which will be a much worse problem than a DCC short. 

 

If you have a railway room that gets really hot in summer, then don't do tracklaying in winter ….

[PaulRhB]

Used to have an issue with heat in my dads shed. We blocked the windows and installed a thermostatically controlled fan to pull out the hot air under the eaves. If we did it again we'd use a solar powered fan. It was enough to stop track buckling so should help in your case. Much cheaper than aircon even if it doesn't cool it as much.

[Ian J.]

Do as the real thing? See if you can find Peco SL44:

 

http://herefordmodels.com/index.php?main_page=product_info&products_id=898

 

Searches seem to show them in short supply, but if you have normal model railway gaps for electrical sections, then using a few of these in suitable places might actually work...

[roy h]

also had a few issues at the moment as ive been in the attic a few times the last week to do little things as the glue sets quicker. but last night decided to run a few trains and found the lenz lvz has decided not to play ball. light on the front slowly flashing and still dose it when all track connections are removed so hopefully when things cool down all will return to normal.

[Free At Last]

This helps to keep the heat out of my shed, be better when I have finished the insulation.

 

I had several strange shirts in the '60s but I'm too old to be wearing that kind of stuff now.

Edited July 2, 2018 by Free At Last

[Phil Bullock]

Insulated RJs are a must!

 

Also on our portable layout with 3ft boards theres a temptation to lay straight across the board with a single length of track.... but experience says no.

 

We use copper clad PCB sleepers at board joins so no expansion possible there - track laid without expansion joints has resembled a letter S when boards were over radiator at our first show!

 

So now always at least two track joints on each board - although next layout will be CWR on concos will still stick to that...

 

Phil

[SM42]

I'm not sure where you keep your layout and therefore this  may sound odd but can you open a window, preferably once each side of where the layout is. 

 

Here at SM42 towers we open the windows at front and back and let the breeze blow through. This makes a good 5 or 6  degrees difference, very useful when trying to sleep at night (but still too warm  for modelling as the Liquid Poly sounds like a bottle of fizzy pop when I open it). . If you have windows in the railway room, cover them to keep the worst of the sun out i.e , close the blinds or whatever covering you choose.

 

Good luck. 

 

Andy

[newbryford]

If track is well fixed down, there shouldn't be expansion (or contraction) issues if the rail ends are either secured or protected with IRJs.

 

I try to lay track in a warm room and will totally avoid laying it in anything below 20C.

 

Retrofilling of gaps can be either plastic as suggested or a small blob of two part epoxy - filed/profiled to shape once set.

Edited July 2, 2018 by newbryford

[RFS]

also had a few issues at the moment as ive been in the attic a few times the last week to do little things as the glue sets quicker. but last night decided to run a few trains and found the lenz lvz has decided not to play ball. light on the front slowly flashing and still dose it when all track connections are removed so hopefully when things cool down all will return to normal.

 

Had that problem too with the Lenz LZV100 thermal trip.  I have a 12v DC supply passing close by feeding some signals, so I fixed a 120mm computer fan (also 12v DC) above the LZV100, so now whenever the layout is powered up the fan keeps the air circulating above the Lenz equipment on its shelf. 

[Dagworth]

A drop of thick superglue in cut joints will stop them closing up in hot weather. 

I've never had a problem with ballasted track buckling, but have seen unballasted fiddle yard roads go distinctly off true.

 

Andi

[chaz]

Expansion and contraction are inevitable with changes in temperature. I learnt this a while ago on a layout that had a removable section. The ends of the rails on that section were soldered to brass screws. This prevented the rails from moving forward and back so the track bent vertically, enough indeed to lift the track pins in the centre of the section by a few mill'.

 

Incidentally a friend of mine, who once worked on the railway, told me a tale that is relevant. A track gang was working on relaying a piece of rail on the Romsey curve out of Eastleigh. A new piece of rail had been cut to length and then the worn rail was removed. When they attempted to fit the new rail they discovered that the rails either side had expanded and the rail would no longer fit. The discrepancy wasn't great but enough to cause a problem. As a solution (time was pressing) the track panels either side were lifted enough to get the rail in and then pressed back down again by running the class 33 standing nearby over the section forcing the rails either side to slide a little.

 

Chaz

[DCB]

The shorts are caused by using rail gaps as insulators, The cure is to not use rail gaps as insulators. Track expands in hot  weather and if exposed to sunlight needs both expansion gaps and an ability for the rails to slide in the rail fixings, if it doesn't slide the fixings rip out. 

I have 60 yards of so of single track "main line"track outside and always try to lay track this sort of weather. That way I can use gaps of a stanley knife blade width and with everything firmly ballasted with sand cement mix the track pretty much stays put. Downside is I can't use track power as the sand cement mix is a conductor, not a great one but when there is 60 yards of it its enough to sap the power of even a 5 amp power supply.

 

Inside the shed is kept as dark as possible and if starting again the shed would only have windows at eaves height and shutters over them.  The track on the lifting section by the window expands furiously and used to need constant fiddling and re soldering until I cut it into short lengths with extra fish plates and really anchored the ends by screwing long brass screws into the baseboard frame and soldering rails to them and letting the rails slide in the chairs and fishplates to take up the expansion.

Before laying flexi track I de burr the rail ends and pull the rails from the sleepers, this ensures they will slide,  A batch of Crap Trak of which I bought many yards is incapable of having the rails removed without breaking the rail fixings on the sleepers, so it remains unused or lurks in the darkest depths of the most hidden sidings.

 

Expansion considerations affect the full size railway, generally straight sections suffer, curves push sideways to relieve stress, hence many viaducts and bridges are curved, the old 60 track foot panels had to have their fishplates oiled so they could slide with temperature changes.   Awkwardly the ideal of a fishplate every 60 scale feet to allow expansion is the exact opposite of what good electrical continuity requires, and in my experience the smaller rail sections are affected far more than the good old chunky ones and N/S more than Steel.

 

Hand built track with N/S rail on PCB sleepers is liable to completely disintegrate if left in bright sunlight, 

[Pete the Elaner]

I have been trying to work out the deflection caused by thermal expansion. I got part way with it.

I found that a 1m length of Nickel Silver rail should expand by about 0.5mm after a temperature rise of 20c. That doesn't sound like much does it? It could be that our track can suffer bigger temperature differences than this, depending on its environment. Sheds or lofts can get very cold in winter & very hot in summer.

If we use the 0.5mm expanasion as an example & assume that both ends have been fixed hard to pins or copperclad sleepers which will not budge, or are hard against another piece of rail, then the rail will buckle. How much will it buckle & is this a problem?

This is where I got stuck because the rail would try to form an arc, but I can't work out the formula for this. We can see what damage it will do by wrongly assuming that it would form 2 smaller straights with a kink in the middle, so here we go:

 

Using the original length of the rail as the base of a triangle & the expanded length as the hypotenuse, we can use pythagoras' theorem to work out the deflection.

Expanded = hypotenuse, so we can use E for this.

Original = base, so we can use O for this

Deflection = height, so we can use D for this.

 

E^2 = O^2 + D^2

(500+0.25)^2 = 500^2 + D^2

D^2 = (500.25)^2 - 500^2

D^2 = 250250.0625 - 250000

D^2 = 250.0625

D = 15.813mm

 

So that is 15.813mm deflection caused by a temperature rise of 20c. I was quite shocked by this measurement.

This certainly justifies small gaps at each rail join or insulated rail joiners, which are soft enough to allow the rail to expand while staying straight.

 

It also illustrates the problem real railway engineers have, although they use steel rail which expands at a different rate, it is exposed to more extremes of hot & cold.

[GoingUnderground]

Wood also expands and contracts with changes in temperature, so there will be some compensation for track expansion by the wooden framework of your baseboard doing likewise, but less so. I hadn't thought about it before, but even modestly sized layouts in places that are likely to experience the extremes of temperature changes through the seasons, probsbly need to include rail expansion joints. Rail may creep, as whilst the expansion is linear, the movement may be affected by other physical factors. So soldering the rail at just one place along its length to a nail through the top of the baseboard will keep it in its correct place long term through many temperature change cycles. Use long copper nails so they stick out below the baseboard top and you've got built in droppers.

Edited July 3, 2018 by GoingUnderground

[GoingUnderground]

I have been trying to work out the deflection caused by thermal expansion. I got part way with it.

I found that a 1m length of Nickel Silver rail should expand by about 0.5mm after a temperature rise of 20c. That doesn't sound like much does it? It could be that our track can suffer bigger temperature differences than this, depending on its environment. Sheds or lofts can get very cold in winter & very hot in summer.

If we use the 0.5mm expanasion as an example & assume that both ends have been fixed hard to pins or copperclad sleepers which will not budge, or are hard against another piece of rail, then the rail will buckle. How much will it buckle & is this a problem?

This is where I got stuck because the rail would try to form an arc, but I can't work out the formula for this. We can see what damage it will do by wrongly assuming that it would form 2 smaller straights with a kink in the middle, so here we go:

 

Using the original length of the rail as the base of a triangle & the expanded length as the hypotenuse, we can use pythagoras' theorem to work out the deflection.

Expanded = hypotenuse, so we can use E for this.

Original = base, so we can use O for this

Deflection = height, so we can use D for this.

 

E^2 = O^2 + D^2

(500+0.25)^2 = 500^2 + D^2

D^2 = (500.25)^2 - 500^2

D^2 = 250250.0625 - 250000

D^2 = 250.0625

D = 15.813mm

 

So that is 15.813mm deflection caused by a temperature rise of 20c. I was quite shocked by this measurement.

This certainly justifies small gaps at each rail join or insulated rail joiners, which are soft enough to allow the rail to expand while staying straight.

 

It also illustrates the problem real railway engineers have, although they use steel rail which expands at a different rate, it is exposed to more extremes of hot & cold.

As you say, Pythagoras can only give a rough approximation as it ignores the fact that the rail would bend.

 

Taking your assumption that it would form a perfect arc, i.e. part of a circle, then using your data, the deflection is slightly less, 13.694mm, using an online calculator (at www.handymath.com The complete Circular Arc Calculator).

 

I agree, the figure is surprisingly large, but it doesn't allow for any thermal expansion of the baseboard material, which will reduce the expansion. For the sake of argument, assume that wood only expands half as much as the rail. So whilst the rail expands to 1000.5mm, the baseboard would itself expand to 1000.25mm. Using these figures, the deflection becomes 9.684mm.

 

We shouldn't forget that the reverse holds, true, the rail will contract more than the baseboard with a drop in temperature.

 

Either way, better to build in expansion joints, and try to lay track when the temperature is about 20 degrees Centigrade.

Edited July 3, 2018 by GoingUnderground

[newbryford]

Wood also expands and contracts with changes in temperature, so there will be some compensation for track expansion by the wooden framework of your baseboard doing likewise, but less so. I hadn't thought about it before, but even modestly sized layouts in places that are likely to experience the extremes of temperature changes through the seasons, probsbly need to include rail expansion joints. Rail may creep, as whilst the expansion is linear, the movement may be affected by other physical factors. So soldering the rail at just one place along its length to a nail through the top of the baseboard will keep it in its correct place long term through many temperature change cycles. Use long copper nails so they stick out below the baseboard top and you've got built in droppers.

 

Wood does various things with heat. If it contains a significant amount of moisture it will swell, but then as it starts to dry out, it will shrink.

 

Worst situations I've seen were with a layout stored in a cold shed over winter (so absorbed some moisture) and then exposed to a warm exhibition hall. A double whammy with expansion until the wood dried out a bit by day two and started to shrink back.

 

Cheers,

Mick

[GoingUnderground]

Wood does various things with heat. If it contains a significant amount of moisture it will swell, but then as it starts to dry out, it will shrink.

 

Worst situations I've seen were with a layout stored in a cold shed over winter (so absorbed some moisture) and then exposed to a warm exhibition hall. A double whammy with expansion until the wood dried out a bit by day two and started to shrink back.

 

Cheers,

Mick

Totally agree. It also depends on the type of wood as well as whether it's man made, e.g. MDF or chipboard, or timber, and how it's been treated. I was just trying to keep things simple for the purposes of the calculation.

Edited July 3, 2018 by GoingUnderground

[WIMorrison]

Many wise words suggested by people and many that with the wonderful gift of hindsight that I (and I expect many others) should have done when building the layout - unfortunately thatw as not the case and I am not (currently) planning to rip it up to fix it 'properly'.

 

What I am going to do is slice the gaps that are causing the issues just now which will remove the issues that the system is having. When the track cools down (anyone have a crystal ball that tells me when it is going to rain again?) I will fill small gaps with superglue paste and if there are any large gaps (remember I am modelling in H0e) I will fill these with Milliput and file to shape.

 

TBH, that is what I was always going to do and I wondered if there were other clever suggestions that were going to save me the work, unfortunately I am left with this solution but it is heartening to know that I am not alone and interesting to see the solutions that have been adopted - I especially like the extractor fan at the apex, however whilst that is where the hot air I want to get rid of in the summer resides, it is also where the warm air that I need to retain sits in the winter and it would leak out very quickly

 

Thanks again - lets keep up the discussion on potential solutions - I especially like the suggestion that a 0.5mm expansion of the rail means a 13mm deflection of the track, that surprised me a lot and the figures are correct which shocks me even more!

 

Iain

[Andymsa]

Hi

 

I know you said aircon was not an option, but with this heatwave I have been thankfull for it, aswell as my track work. Please don't laugh the only downside I get cold feet as I don't ware socks in this heat

[Pete the Elaner]

 I especially like the suggestion that a 0.5mm expansion of the rail means a 13mm deflection of the track, that surprised me a lot and the figures are correct which shocks me even more!

 

My initial (rather crude) calculation was prompted by a chat my local club where we decided that thermal expansion has little effect on model railways & was not worth worrying about.

How wrong we were! 13mm is huge.

As pointed out, there are other factors to consider too, because everything moves a little, but rail breaks with small gaps at regular intervals are definitely a good idea & I shall treat these less casually in future.

 

I am still annoyed that I could not derive a formula for calculating the deflection of an arc instead of having to cheat by using straight lines   , but the calculator suggested by GoingUnderground looks excellent.