I've been doing a bit of turnout work on Thunder Ridge this weekend. Most of my turnouts are hand laid using PC Board ties and solder. The work I'm doing now is going back to add powered frogs and unfortunately, I'm finding that my old solder joints are becoming brittle and breaking. I remember reading something long ago about different types of solder and their ability to hold under tension, but I haven't been able to relocate that info. Does anyone have any info about solder strength and/or a recommendation of what I could do to prevent further solder joint breaking? Any help is much appreciated! (Go figure this happens the very day after I paint the rail & ties on these turnouts!) :curse:
NO idea. I've soldered hundreds of turnouts without problems. I use PC board ties, electronic solder rolls and no extra flux. My electronic tin-solder type Sn60Pb39Cu1 has some rosin type flux already. Did you get some "cold spots"?? Wolfgang
Mark, I agree with Wolfgang, sounds like you have some cold solder joints. These can be repaired in place by reheating the joint, including the base metal, to the solder's melting point, then allowing it cool slowly. Be sure that the joint is NOT under stress when you remelt it, or it will separate. Cold solder joints are created a couple of ways. First, by not allowing the base metals to reach the melting temp of the solder when the solder is melted, thus not allowing the solder to bond with the base metal. Second, by forcing the joint to cool too rapidly before the solder has fully bonded with the base metal. Interesting side note on this latter condition...a plumber working on my house consistently had leaking joints with copper pipe. This was caused by him being so concerned with good looking joints that he immediately wiped every joint with a wet rag to get rid of errant solder flowing away from the joint. Of course this caused an immediate cold solder joint due to the rapid cooling, and leaking joints.
Interesting. I guess you learn something new every day! I've blown on joints on occasion to have them cool faster, never knowing this may weaken the joint. However the majority of the time I let the solder cool naturally. I am very generous when it comes to applying paste flux, usually allowing me to "get in and get out" with the soldering iron. Perhaps this is just not allowing the base metal to heat enough as Hytec suggest. Yep, most of my solder joints look dull rather than glossy. And here I am, always thinking my soldering technique was down pat. Thanks for the tips guys!
Soldering paste boils as you can see. Too much paste will keep the base metal cool, at the boiling temperature of the paste, even though you have melted the solder with the iron. This is why a boiling pot of water will never get hotter than 212F degrees. The best way to solder a joint is by heating the base metal from the back, or opposite side of the joint from the solder. This is often impossible, so the second best technique is to lay the tip of the iron on the base metal and feed the solder into the joint as far away from the tip as possible as the paste boils off. Be sure to have a clean iron tip with a good solder bridge to get the best heat transfer. Any slag, or poor bridge will block heat transfer. Small diameter solder, .015", and an 18W conic tip iron are best for soldering track, locomotives, or electronics, because they are the easiest to control when feeding solder into a joint.
Great advice from everyone. A few more hints: 1. Heat the work, not the solder. As others have said, the work (your track in this case) must get hot enough to melt the solder without you touching the solder with the iron. 2. Cleanliness is essential. Keep a damp sponge or cloth nearby, and wipe the tip of your iron on it before and after every soldering operation. Make it a habit: wipe-solder-wipe, wipe-solder-wipe, etc. 3. Let it flow. When you touch the solder to the work, it should instantly melt and flow into the joint. If it doesn't melt right away, the work is not hot enough. 4. Smooth, not lumpy. In addition to being shiny, a good solder joint should be smooth. If your solder joint looks like a "lump" of solder sitting on the work, it is likely to be a brittle joint. - Jeff
I am an infrequent solderer. I was better when I was laying track as you get more practice, practice, practice. I certainly learned some things in this thread.
Thanks Jeff. Here's another question. I've always used tweezers to press the rail against the PC Board tie while the soldering iron rests alongside the rail just off the surface of the PC Board and using my pinky finger to feed the solder into the joint. Should I not be so worried about pressing the rail so firmly against the tie? I'm starting to wonder if this pressure is not allowing the solder to flow between the two and therefore adding to the weakness of the joint. Oh, Jeff.. I also notice your other hobby related to Astronomy! I'm in the process of budgeting for an Astrophotography setup. If you have any knowledge or experience you're willing to share, I have many questions. Are you a member of the off-topic "cattle car" forum? I have an Astronomy thread running there.
Mark, tweezers will wick heat away from the joint, thus not allowing the joint to heat properly. It would be better to apply weight an inch or more away from the joint to gaurantee rail/tie pressure, or apply a shim of wood beneath the tie for the same result. BTW, the molten solder will easily wick into any miniscule space between the rail and the tie if the solder is hot enough to flow continuously.
