I have an Alco P&LE Berkshire and there was a rubber hose between the motor and gearbox that would always slip due to play in the worm gear. So to fix the issue I bought a coupling set from NWSL. During installation the brass support bar that holds the motor on came off. The solder joints the hold it on apparently broke. So I am trying to re-solder this thing, but Im not sure my gun has enough juice to do it. It claims to be a 240 watt gun. After holding it on there for quite a long time I was able to get a blob of solder on there, but it definitely looked like a cold joint and didnt hold at all. Any thoughts? As an FYI I do know how to solder… I’ve done surface mount stuff all the way up to sweatin 3/4" copper pipe! I cleaned off the frame and part, but it just seems like I just don’t get enough heat. Any thoughts would be appreciated. I’d love to actually get this engine running someday. I definately didn’t buy it to sit on my repair desk!
I’d suggest tinning both the bracket and the area where it mounts, then trying again. I usually use a 200 watt iron for such work, as you need lots of heat applied quickly. If your gun isn’t up to the task, the plumbers propane torch which you used to sweat those pipes together will do the trick. You’ll need a method to hold the part in position while heating it, and it’s best to remove any nearby plastic parts and, of course, the motor. To protect the soldered joints which hold the frame together, along with those holding any details in place, use wet (not merely damp) paper towels, packing them around all joints which you wish to protect. You can use smaller chunks where required, and secure all tightly with clamps or alligator clips where necessary. The torch will apply a great amount of heat quickly, so as soon as the solder melts and the piece is in position, remove the heat. The wet towels nearby will hiss and emit steam during this procedure, but as long as they do, they will be keeping the joints cool. If, for any reason the joint is not satisfactory, re-wet the towels before trying again.
I used the same technique when assembling and detailing this old Akane brass loco, and even with the torch or large iron, had no problems with nearby details coming loose. Even some plastic construction survived nearby soldering.
Wayne
For that sort of work, an iron, as big as will fit, is better than a gun. The heavy tip on the iron is a heat reservoir. Heat rushes out of the tip to heat the work. A gun has just a bit of copper wire for a tip that doesn’t hold much heat, so it cools down when you press it on the cold work and the electricity has to work extra hard furnish the heat.
On the other hand, I just soldered a cast brass pilot to a beefy piece of brass bar stock with a 250 watt Weller gun no sweat. Might be your gun needs a new tip. Over time the gun tips burn off copper, raising their resistance and lowering the amount of heat they generate. Also, if the tip securing nuts or screws get loose, the tip will run cool.
You have some real good suggestions already. You need to use flux on the old solder. Also you should use a bit of new solder on your iron tip to make a path for heat transfer through the solder. The old solder might be high melt temperature solder. Use new solder to make the joint.
Something like that could be a real problem. Clean the pieces as best you can, clean off as much solder as possible, using heat if you have to, but carefully.
After that is done, you need some flux (use rosin flux) on both pieces. Apply solder to both, wipe off the excess and apply more flux when it cools. Then assemble them and try to sweat them together.
Now, your best option is to find someone with a resistance soldering rig, as it can develop a lot of heat in a small area very quickly. Problem with large parts, they soak up heat very well, and you need a large tip on a hot iron, which can be a problem. Getting it in there is the first problem, and leaving it too long to get the work up to temperature could also melt the solder in other joints.
You could also use the handyman’s secret weapon: epoxy. Something like JB Weld might fit the bill.
What about using some caulking like we use when attaching a can motor? There appears to be plenty of area for that. Any thoughts there? I would just have to run a wire from the motor to ground, but when I go DCC down the road this might be an advantage. Any thoughts?