I started out by soldering the outside rails in place, having first filed out the areas where the blades will fit. I then made up and placed the frog. This was a bit more of a challenge as there is a curve running through it. I'm not sure I've got it quite right. Then I soldered in the first blade. There is is a bit of wheel drop through the knuckle but its not too bad when the wagons are pushed through it and it should sort itself out once the check rails are in place.Also note the nice curvature that one can build in with hand laid track. I'm starting to really enjoy making it (and will probably continue to until I have to face a scissors crossover).
As a further question, does anyone know what the expansion coefficient of nickel silver is? I might have to start thinking about gaping some of this rail.
6 comments:
that looks awesome eh?
wouldn't it be enough just to cut a gap into the rails every now and then (with a Dremel tool or the like) for the eventual expansion after you are finished with laying all the track ? just a thought...
steve w.
'zygra'
Standard cupronickel: 16 µm/m/K.
Since nickel-silver [sic] will have zinc replacing about half of the copper in standard cupronickel, it will be different, but not wildly different.
Nickel by itself is 13 µm/m/K; copper 16 µm/m/K, zinc is 30 µm/m/K. The relationship between expansion coefficient and mole fraction won't be linear either, but again, it won't be *massively* non-linear. You wouldn't go far wrong with 18 µm/m/K, I guess.
So its essentually sod all unless I was going to have 10M lengths. I wonder why then it is percieved to be a bit of a problem.
Well, that still gives half a millimetre of expansion per metre of rail length, if you have a temperature difference of 25 degrees over the year - if your room goes down to say 10 in winter (hell my room at Castle St in Dunedin went down to freezing!), and in summer any part of the track is exposed to direct sunlight, it could easily climb to 35 degrees. Is half a millimetre a problem? I guess it might be if you have continuously soldered track. But a couple of quarter-millimetre gaps every metre sure as hell won't be noticeable, and will cover your expansion nicely, so why not?
Maybe the next big breakthrough in NZ120 is scale continuously welded rail expansion joints? I doubt 0.5mm will affect running reliability at all.
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