Track expansion??

[Sprintex]

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

[polo2k]

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

[Sprintex]

Yep, doesn't take much change in temperature or humidity for the pesky kitchen door to start sticking! 


Paul

[Bikeracer]

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

[dodger]

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.

[Bluebottle]

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.

[Boosh]

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

[polo2k]

[devils advocate]
should we cut expansion gaps in the boards too?
[/devils advocate]  

[Boosh]

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!

[Newportnobby]

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

[Boosh]

Not sure why I'm calling people Dave... sorry Dave, or Ash even 

regards
Dave

[kirky]

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

[jonclox]

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?

[Boosh]

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?

[Newportnobby]

Certainly food for thought Just one drawback - getting the salesman out of your house after 5 hours