11-05-2009, 10:03 AM
Note that "expansion due to temperature changes" in nickel silver rails accounts for about 15% of the changes we see when our tracks buckle. The heavy preponderance of the buckling effect is due to changes in humidity and the resultant expansion of the cells in the woods we use to construct our layouts. In fact, the expansion is actually due to the rail lengths being pulled away from each other as the wood loses humidity and shrinks. When you see your track gaps widening, it is because the wood has regained some moisture content and had lengthened....thus taking the rails apart from each other. Think about the randomly distributed raisins in bread dough as it rises. As the dough expands, the raisins move further apart since they have no motive power of their own.
It was demonstrated to me mathematically on another forum that N/S rails expand very little over swings in temperature of even 30 degrees. The person proved that a contiguous length of 100' of Code 100 (meaning one monolithic rail length of 100') would expand a whopping 1/4" along its length over a rise of 30 degrees. I suspect that we all have an accumulated total of 1/4" in gaps along our track systems, and that those gaps really comprise a total more like 1/2 - 3/4" on a typical layout. So heat is not the problem...humidity is the problem.
Solder the tangents rarely, and solder the curved lengths often...to get good curves. Let the tangents slide in non-soldered joints to help your system withstand the ravages of humidity.
-Crandell
It was demonstrated to me mathematically on another forum that N/S rails expand very little over swings in temperature of even 30 degrees. The person proved that a contiguous length of 100' of Code 100 (meaning one monolithic rail length of 100') would expand a whopping 1/4" along its length over a rise of 30 degrees. I suspect that we all have an accumulated total of 1/4" in gaps along our track systems, and that those gaps really comprise a total more like 1/2 - 3/4" on a typical layout. So heat is not the problem...humidity is the problem.
Solder the tangents rarely, and solder the curved lengths often...to get good curves. Let the tangents slide in non-soldered joints to help your system withstand the ravages of humidity.
-Crandell