[Richard Johnson]

**Yes you are right but expansion and contaction will be more from timber movement than rail (wood moves much more than nickel silver).

Paint or seal all baseboard timber on all surfaces.

reason:

* when its hot, wood dries and shrinks - at the same time, the rail expands a little.
* When its damp and cold, wood expands and nickel silver rail shrinks.

If you are laying track in winter, then regular gaps should be about 1mm.

After sealing the timber, the next best additional protection is air conditioning for humidity/heat control but thats possibly a little exteme - as a substitute a fan heater on a timer in winter - set it to run on heat for say an hour two or three times a day to keep humidity minimised and on fan only in summer to keep air flowing to keep things cooler (hot air gathers in the roof space).

Also if you can, a light plastic sheet over the layout between uses will minimise any condensation / moisture in winter and dust on the layout in summer.

Richard

 

[Richard Johnson]

*** Hi Rob

Sundeala is more related to cardboard than wood in a way, but I'd think it was as prone to movement as any form of similar cellular product.

I certainly have no idea why you should leave one side unpainted - it sound a little like an "urban myth" like so many similar comments.

I'd have thought that logically, with both sides covered/sealed stresses would be evened out and sealing would increase not decrease stability. A coat of paint or sealer would have no effect on noise.

Richard

 

[Richard Johnson]

*** Hi Mike - the 1/2mm is quite true as an average - I suggested the 1mm as in UK its mid winter, with max dampness in the wood and coldest state of the rail. It may be OK to be less if the conditions are controlled or the area is heated, but there was no indication of that. (Likewise if the rail is laid in mid summer like it is here when wood is shrunk back and rail at max expansion, I'd probably have recommended far less).

Richard

 

[Richard Johnson]

*** Hi Mike

DOn't believe all the rumours - many AU modellers have nice environments, but there are just as many "shed" layouts here as in UK.

which is more of a problem - humidity changes or temperature changes?

It depends on the extremes-- for example, if I had a layout in a shed here, the outside temperature may be say 35 degrees c but at the layout point where the afternoon sun shone in a window, it could be 50, 60c or more.... In that case, locally, heat would be the issue.

However, I think its always a combination: Summer is hot and things dry out when its hot. Winter may or may not be all that wet but it follows autumn when rain is generally high, so cold and damp happen together too... Impossible to separate them as "layout environmental issues" really

regards

Richard

QUOTE (Mike H. @ 21 Jan 2009, 16:43) <{POST_SNAPBACK}>Many thanks Richard ... I read with some envy about our American (and Australian?) friends who do not have this problem - thanks to aircon they can simply solder the lot and not worry about thermal expansion/contraction at all.
In general terms though, which is more of a problem - humidity changes or temperature changes?