The Eds are right that 60/40 will work on curves if you're filling in around a rail joiner. But Randy's right about the dramatic differences in strength depending on the specific formulation. I suspect a lot of the soldering in switchwork depend soley on the strength of the solder joint with no mechical assistance from a railjoiner, etc.
Yes, silver solder is the strongest and that's why jewelers use it. But I use silver-bearing solder as the all-around standard on my layout. Makes tugging wires much less anxiety-inducing. I've built brass locos with it. And for trackwork, it's been great. I used the Radio Shack 62/36/2 silver-bearing solder, but have found a quite similar 62/36/2 product at Amazon now that the RS is unobtanium that works just as well.
Mike Lehman
Urbana, IL
That's the way I did mine. First step, solder two pieces of flex together - at the work bench. Second step - go to the layout and curve the track to fit. No kink, the joint was already stablized by soldering it.
I just used ordinary 63/37 solder. Not silver bearing. Seems planty strong enough. I built a Fast Tracks turnout with it, it's suvived being tossed about in boxes and none of the PCB ties has yet to break off.
Seems like a minor difference 63/37 vs 60/40, but there is one important difference int he chemical properties. 63/37 is eutectic, both components melt and freeze at the same temperature. 60/40 is not. The tin and lead melt and frezze at slightly different temperatures. With 60/40 you have to be more steady with waiting untilt he joint cools without moving it - moving the joint before the sodler totally freezes results in a 'cold' joint, usually easily visible by being dull in color and not shiny and bright (another reason to hate lead-free solder - all of it is dull looking, even with a good joint, so it's harder to tell). With a eutectic solder, it's either all melted or all frozen, so as soon as it frezzes, you're good, with 60/40 one part freezes first and if you move the joint before both parts freeze, you effectively seperate the two components of the alloy.
Depending on the formulation some silver bearing solder is eutectic and some is not.
I'd say a eutectic alloy like 63/37 is easier for a beginner to get good joints with - and since I never had a reason to use anything else, I've never changed, still use 63/37. I don't eat it, and I wash my hands after working with solder, so I do not fear that it contains lead. The fumes from solder, btw, are not lead fumes - it's the flux. A soldering iron does not get hot enough to actually vaporize lead. Still, not something you want to breath in on a regular basis, so keeping the work area ventilated is always a good idea.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Back when I had an HO layout built with flex track, I used the approach to solder my joints with the track in a straight line but I slid my ties back a bit first. Worked great. This allows you to curve the track with virtually no kink in the track at the soldered joint.
Paul D
N scale Washita and Santa Fe RailroadSouthern Oklahoma circa late 70's
There is a difference between silver solder and silver-bearing solder. The former requires a torch, the latter a soldering iron. The former is dramatically stronger than the latter. With silver solder, you could butt-join two rails without a rail-joiner, and the joint would not fail, even if you hammered on it. I have done so.
However.
In a curve, I completely agree that regular soft solder filling in the rail-joiner will be entirely adequate and is the best choice.
Other Ed
If I were scratch building a turnout I'd probably consider silver-bearing solder, yes. However, we are talking about mostly bare rails held in a jig and a few P-C soldered ties. These would take the heat OK.
I soldered all the joints on my curves, while the track was still straight, with tin/lead 60/40 solder with no problems. The solder is plenty strong enough to hold the rails in alignment. Trouble with silver solder here is that the added heat needed might cause more melted ties.
Any slight kink on a curve was the result of the joiner itself getting bent not a failure of the solder.
Good Luck, Ed
Recently I saw a video about hand laid turnouts. They used silver solder on certain parts because it was much stronger. How about rail joiners on curves?