I have read on various threads about track expansion does this happen much? how long does the track run need to be for it to be an issue? does laying track with curves in contain the problem same as expansion loops in pipework?
Dave
Quote from: bbdave on January 19, 2012, 03:39:40 PM
I have read on various threads about track expansion does this happen much? how long does the track run need to be for it to be an issue? does laying track with curves in contain the problem same as expansion loops in pipework?
Dave
Track does expand but the expansion co-efficients involved are tiny. Also in theory of course the boards expand too.
In practice however what happens with traditional construction is that when it gets hotter it gets drier and the wooden baseboard shrinks a bit. If you have long lengths of flex with no small gaps in the joins it can then be a problem. One good reason you should always properly varnish wooden baseboards and their framing.
I don't know what happens with the newer foamboard designs. I'd be interested to know if anyone has built one big enough to tell if there is a problem and what they saw ?
Alan
I would agree timber expands but i thought ply would solve most of this and no amount of varnish totaly seals wood from a damp almosphere.
My father is considering soldering his joints hence the question as he thinks that there wouldn't be any significant problem.
Dave
Quote from: bbdave on January 19, 2012, 05:26:22 PM
I would agree timber expands but i thought ply would solve most of this and no amount of varnish totaly seals wood from a damp almosphere.
My father is considering soldering his joints hence the question as he thinks that there wouldn't be any significant problem.
Dave
If you're going to have ply, maybe you'd be best off with marine ply and a suitable spec varnish ???
Quote from: bbdave on January 19, 2012, 05:26:22 PM
My father is considering soldering his joints hence the question as he thinks that there wouldn't be any significant problem.
Dave
I initially soldered a lot of Wadebridge which is ply over Ikea pine furniture so the pine I am sure did resize and it gets very hot/cold where it is. That gave me problems with track buckling and I had to add one real break.
The prototype approach of joining it on a very very hot day didn't work either (I tried that first), the solder joint fractured when it got cold.
I have had the problem in the past with a layout stored in an unheated shed. It broke a number of solder joints across a base board joint
The outdoor modelling crowd get over expansion by not soldering every joint and leaving a small gap between tracks held by a rail joiner to allow for expansion. Electrical feeds can be sorted by soldering a small wire loop across the gap which will allow for the expension.
:Class414:
Quote from: bbdave on January 19, 2012, 05:26:22 PM
My father is considering soldering his joints hence the question as he thinks that there wouldn't be any significant problem.
Question I would ask is
why is he considering soldering the joints? What significant advantage does he expect to gain over using traditional rail-joiners?
If it's for better conductivity he'd be better using a powerbus system, whether it's DCC or DC :)
Paul
In all honesty he comes up with the most complicated way of doing things so if it's hard to do he'll try it. I'm visiting him this weekend so hopefully get him back on track (excuse the pun) i'll try to get some pics of his layout to post aswell.
Dave
I've been a bit bored this morning, and not feeling too inspired to go and do some modelling.I therefore decided I would do a little track expansion test. Ok, its not scientific, but it certainly demonstrates to me the lack of expansion in track.
Firstly I took a piece of peco code 55, small enough to be measured using my digital vernier scale, giving me an accuracy of 1/100th of mm. The piece I found was about six inches long, and was in my railway room, my loft. There was no heating on in there but even though its cold outside, I would say its still at least fifteen degrees up there, and probably warmer. I also decided I would put the track outside where the car thermometer says 3 degrees. I thought it was worth double checking very cold temperatures and thought I could try the freezer. Finally the warmest place I could find was on top of a radiator, when turned on is too hot to touch for more than a second or two.
Here are the results
Loft 147.66
Outside in snow 147.70
In Freezer 147.68
On radiator 147.67
Which basically means I either can't measure very well (which is likely) or the differences are so negligible that it looks like the track expands with COLD and shrinks with HEAT.
So as Alan has said above, the most likely cause of track movement is down to damp wood shrinking when it dries out.
just thought I'd share this.
Kirky
Quote from: kirky on February 05, 2012, 01:11:47 PM
Which basically means I either can't measure very well (which is likely) or the differences are so negligible that it looks like the track expands with COLD and shrinks with HEAT.
Sorry to say it but I think your already-acknowledged measuring prowess is the more likely scenario ;)
Almost everything expands with heat and contracts with cold except some anomalous substances, most notably water (expands as it cools from 4C to 0C), as well as elements silicon, bismuth, gallium, antimony, germanium and plutonium (none of which are constituents of nickel-silver rail, being copper, nickel and zinc) as well as a few other compounds.
Well done for having a go at measuring though, at least we can probably assume now that problems are more down to board shrinkage than track expansion :thumbsup:
Paul
Interesting, thanks Kirky.
Quote from: Sprintex on February 05, 2012, 01:33:05 PM
Well done for having a go at measuring though, at least we can probably assume now that problems are more down to board shrinkage than track expansion :thumbsup:
Paul
And that is exactly the point I was trying to make. The expansion/shrinkage rates are so small they cannot measured reliably even down to 1/100th mm. A much more scientific approach is needed to work out what the expansion/shrinkage will be at any given temperature because the expansion/shrinkage is so small. And for our :NGAUGE: purposes, probably negligible. Unlike the question of what happens to the wood on which our layouts are sitting.
Cheers
Kirky
Interesting experiment, Kirky, with unexpected results.
What was the exposure time in each area out of curiosity please - could be that a garden layout in :NGAUGE: is feasible after all given the right type of support and waterproofed electrics ;D
Quote from: newportnobby on February 05, 2012, 02:39:27 PM
Interesting experiment, Kirky, with unexpected results.
What was the exposure time in each area out of curiosity please - could be that a garden layout in :NGAUGE: is feasible after all given the right type of support and waterproofed electrics ;D
Hi Nobby
I'd say at least an hour exposure time. Certainly enough time to get movement.
Incidently, I re measured the track again on the radiator. It was very hot by this time, and I wish I had some kind of thermometer handy to measure just how hot to the touch it was. This time the reading was more in line with what I would have expected - it read 147.78 mm. Clearly the largest reading, but again by only a few hundredths of a mil - not much! I guess the variation is more to do with the inaccuracy of the vernier than anything else.
Personally I don't see why you cant have :NGAUGE: in the garden, but I think I would still be looking to have it fixed to wooden boards - and that's where the problems are :-\
Cheers
Kirky
If you were using a metal gauge to do the measurement then that was probably expanding and shrinking as well.
Not if all the measurements were done in the same room rather than in the environments where the track was heated or cooled ;) And I doubt the small amount of thermal transfer between the pieces of track and the vernier jaws would make a difference at all.
Paul
they are usually made from duralinium, or similar. maybe holding time might have effected it.
Really though, it prooves that any movement is minimal and probably not the cause of running issues. more likely is the boards moving
Yep, doesn't take much change in temperature or humidity for the pesky kitchen door to start sticking! :smiley-laughing:
Paul
Just my opinion for what it's worth but I think there are too many variables to try and measure track expansion with a hand held verynear and get meaningful results.
Allan
The metal rail will expand as the temperature increases and a wooden base board will contract as the wood dries out. When my layout was in an unheated garage The extreme cold would cause track joints to open and either cause loss of continuity or derailments. Conversely extreme heat would cause uninsulated section breaks to close causing varying operational problems.
Hi folks, I use Kato Unitrack, my layout lives in the garage, it gets pretty cold but warms up nicely during the summer but not as bad as some attics. I put my track in place during the summer, giving a small gap for further expansion, what I have noticed is how these gaps open up during winter, down side to this is fish plate movement, checks have to be made now and again but on the up side is the sound of rolling stock over the joints, most pleasing!, watch out for windows, the sun shining in on a small area of track will cause the greatest amount of problems, apart from that Unitrack has done well.
Hello there,
A length of flexi track will expand by less than 1mm if you bring it in from an icy -10 degrees into a warm 40 degrees... i will explain (longs geeky explanation below)
I looked up the coefficient of linear expansion for Nickel Silver, which has a value of 16.2- 16.7 ppm/degrees celcius, depending on the exact makup of the alloy.
Taking an average value of 16.5 for the coefficient, and working on the feasible minimum and maximum temperatures a section of track might experience in the UK- say -10 C for an unheated shed in winter, and +40 C for an unventilated loft in the height of a hot summer (both would make for pretty uncomfortable operating sessions!! :( ). I worked out that a full section of N gauge flexi track (91.5cm or 915mm) could expect a variance in length of 15.0975 micro meters per degree, so it could vary up to 755 micrometers, which converted to millimeters works out at less than 1mm per metre.
In other words the temperature doesn't affect the track much at all, with respect i doubt that many layouts are constructed to tolerances of a millimetre.
As has already been discussed on here, the main factor in tracks moving would be the baseboard reacting to changes in temperature and humidity.
To mitigate against thermal expansion of the track it would be prudent to allow an expansion gap of 1mm per metre of track run. That should cover the harshest of thermal changes, although in this climate it's hard to know what will come next!
Hope this helps.
Neal
[devils advocate]
should we cut expansion gaps in the boards too?
[/devils advocate] ;) :evil:
Absolutely Dave, I think it looks like having a stable base for the layout is a much more pressing issue than track expansion. Saying that I'm coming from a strictly academic standpoint being pretty inexperienced in the baseboard game!
Quote from: Boosh on February 06, 2012, 03:09:24 PM
Absolutely Dave, I think it looks like having a stable base for the layout is a much more pressing issue than track expansion. Saying that I'm coming from a strictly academic standpoint being pretty inexperienced in the baseboard game!
Dave??? - Are you sure you're not Trigger out of Only Fools & Horses :smiley-laughing: :wave:
Not sure why I'm calling people Dave... sorry Dave, or Ash even :-[
regards
Dave
Thanks for the Geeky explanation Boosh. I think it broadly echoes what my findings were (when you take into account the second reading on the radiator). As has been stated elsewhere, the mainpoint I was trying to make was that wooden baseboard movement is much more likely to be the culprit when it come to track moving on layouts.
Incidently, the impetus for me conducting my amateur science was the result of a discussion at our club. We moved last summer from a very damp environment to a much drier (and warmer) environment. Two or three layouts suffered a bad case of the bendy fiddle yards. So in the process of building Northallerton, a few members have asked if I've left expansion gaps, to which my answer has largely reflected my hypothesis; it's the wood that moves!
Cheers
Kirky
This thread has got me thinking (a risky thing to do for me). Ive done no research but offer this idea to be thrashed about (if its worth it)
The threads thrown up the idea of using softboard 'plastic' etc instead of wood as a base the will remain 'stable' under various conditions as opposed to woods movements. Even allowing 'expansion gaps' where the boards join......presumably to absorb movements in the framework
So..........
Why not use 'plastic'/softboard etc on edge or 'plastic extrusion' as used in double glazing etc. as a basic framework to build it all on.
We know that fluids that 'weld' the 'plastics' together are available so would making baseboards like this be a way out out of the problem?
As I say Ive done no research into the idea but ask would that help us out of our problems?
Quote from: jonclox on February 09, 2012, 11:17:09 AM
This thread has got me thinking (a risky thing to do for me). Ive done no research but offer this idea to be thrashed about (if its worth it)
The threads thrown up the idea of using softboard 'plastic' etc instead of wood as a base the will remain 'stable' under various conditions as opposed to woods movements. Even allowing 'expansion gaps' where the boards join......presumably to absorb movements in the framework
So..........
Why not use 'plastic'/softboard etc on edge or 'plastic extrusion' as used in double glazing etc. as a basic framework to build it all on.
We know that fluids that 'weld' the 'plastics' together are available so would making baseboards like this be a way out out of the problem?
As I say Ive done no research into the idea but ask would that help us out of our problems?
That's interesting Jon, having been a delivery driver taking glass to a company that fabricates uPVC windows, I think that getting a framework fabricated from PVC extrusion to your specification is definitely possible- it would just be a case of finding a local double glazing fabricator and talking to them.
It sounds like a good idea to me, PVC is a very stable material, although I'm not sure if it would bow over time under the weight of a layout?
Certainly food for thought :thumbsup: Just one drawback - getting the salesman out of your house after 5 hours ::)
Quote from: Boosh on February 09, 2012, 12:02:15 PM
That's interesting Jon, having been a delivery driver taking glass to a company that fabricates uPVC windows, I think that getting a framework fabricated from PVC extrusion to your specification is definitely possible- it would just be a case of finding a local double glazing fabricator and talking to them.
It sounds like a good idea to me, PVC is a very stable material, although I'm not sure if it would bow over time under the weight of a layout?
I was thinking more of buying basic lengths of extrusion from them, cutting to shape and size then 'liquid' welding it together as plumbers weld water pipe joints. bracings etc could be added where needed in that case (maybe)
Quote from: newportnobby on February 09, 2012, 12:23:39 PM
Certainly food for thought :thumbsup: Just one drawback - getting the salesman out of your house after 5 hours ::)
Theres a knack to it. Eggs and ale before they arrive. 5 Hrs should be plenty of time to get things in
motion
Quote from: jonclox on February 09, 2012, 11:17:09 AM
This thread has got me thinking (a risky thing to do for me). Ive done no research but offer this idea to be thrashed about (if its worth it)
The threads thrown up the idea of using softboard 'plastic' etc instead of wood as a base the will remain 'stable' under various conditions as opposed to woods movements. Even allowing 'expansion gaps' where the boards join......presumably to absorb movements in the framework
So..........
Why not use 'plastic'/softboard etc on edge or 'plastic extrusion' as used in double glazing etc. as a basic framework to build it all on.
We know that fluids that 'weld' the 'plastics' together are available so would making baseboards like this be a way out out of the problem?
As I say Ive done no research into the idea but ask would that help us out of our problems?
Hi Jonclox
My mate decided he would try and build a baseboard using 'Forex' (this might not be the actual name but its as near as I can remember) which is a plastic that is used in creating signs by printing companies. We had a load of free off cuts that we tried to use. After he eventually found a glue that would weld the sheets end on (I think it was 10 mm thick) he made an 'egg box' construction with single unsupported spans of a 300 mm max length,which basically means it was made into foot square sections. But even with such a short section, it was nothing like rigid, it very wobbly, and although it could have been much stiffer with a top board on, for open board construction, completely unsuitable, in my opinion anyway.
Having said all of that, this was plain board,(imagine a piece of very thick plasticard).This would not be the same in any way with an extruded section ofplastic, which I imagine would be much stiffer.
We no longer have the sample as it got dumped in the club move last year, so no photos I'm afraid.
Cheers
Kirky
Some window and door extrusions are also reinforced with either a steel or aluminium insert,uPVC window frames are welded together and I think getting a joint accurate enough for glue to work might be a problem,plus plastic expands and contracts more than wood.It obviously doesn't absorb moisture but it is less stable temperature wise than wood.
Allan
Quote from: Bikeracer on February 12, 2012, 07:23:49 AM
Some window and door extrusions are also reinforced with either a steel or aluminium insert,uPVC window frames are welded together and I think getting a joint accurate enough for glue to work might be a problem,plus plastic expands and contracts more than wood.It obviously doesn't absorb moisture but it is less stable temperature wise than wood.
Allan
Fair points especially the point about it expanding a large amount.
Never mind it was just an idea from me
nickle silver framed boards anyone? ;)
Quote from: polo2k on February 13, 2012, 06:21:31 PM
nickle silver framed boards anyone? ;)
Hall marked stirling silver would be classier than nickle silver :thumbsup:
still an expansion differential though, unless you use stirling silver rails!
Quote from: polo2k on February 14, 2012, 12:03:21 AM
still an expansion differential though, unless you use stirling silver rails!
Well would that be wrong?
Quote from: jonclox on February 14, 2012, 09:15:41 AM
Quote from: polo2k on February 14, 2012, 12:03:21 AM
still an expansion differential though, unless you use stirling silver rails!
Well would that be wrong?
... after you
You are all looking at this the wrong way round... Rather than ever more fanciful construction techniques, you need to stabilise the environment your layout is in with heating / ventilation / air conditioning depending on where the layout is located.
The best place for your layout is indoors, in the spare room, a short distance from the tea making facilities. :)
Quote from: Flakmunky on February 26, 2012, 08:17:26 AM
You are all looking at this the wrong way round... Rather than ever more fanciful construction techniques, you need to stabilise the environment your layout is in with heating / ventilation / air conditioning depending on where the layout is located.
And then when the power goes off one day or the boiler fails, or the aircon goes pop your layout breaks.
I think I prefer to allow for a bit of contraction of the wood thank you 8)
EP - I was joking re aircon...
But seriously, in your spare room I don't think you need to worry too much about expansion... Even if your boiler does break down!