Track expansion??

[bbdave]

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

[EtchedPixels]

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

[bbdave]

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

[Newportnobby]

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

[EtchedPixels]

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.

[Greybeema]

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.

[Sprintex]

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

[bbdave]

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

[kirky]

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

[Sprintex]

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 


Paul

[Tank]

Interesting, thanks Kirky.

[kirky]

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 


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 purposes, probably negligible. Unlike the question of what happens to the wood on which our layouts are sitting.
Cheers
Kirky

[Newportnobby]

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  is feasible after all given the right type of support and waterproofed electrics

[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  is feasible after all given the right type of support and waterproofed electrics

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  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

[edwin_m]

If you were using a metal gauge to do the measurement then that was probably expanding and shrinking as well.