Soldering music wire...

S

steamhead

Active Member
Apr 16, 2005
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Brownsville, TX
I have a lot (20+ or more...) under-the-table switch machines (solenoid type) mounted and have a steel music wire soldered to the actuator arm which throws the points. Lately I have had several of the music wires flying off the arm to which they were soldered....:cry: I thoroughly cleaned the wire and used flux when soldering it to the actuator arm, which appears to have a plating of some sort (nickel perhaps..??). What am I doing wrong which is causing these wires to go flying off..??

I dread to think that this plague may spread to other switch machines as some are mounted in now nearly inaccessible places....wall1

Any advice would be GREATLY appreciated....:wave:
 
The problem is that music wire is steel, and doesn't take regular Tin:Lead solder very well. You really need to silver-solder it.

It can be tricky, because it requires a fair bit of heat, but I've used this stuff:
SP7.JPG
with good success. It's a paste that you squirt out of a syringe onto a joint, and then heat with a lighter or small butane torch. The flux and solder are combined in the paste, and it makes a nice solid joint. Takes a bit of practice, but it's worth the effort.
 
Gus,

I get mine at a tool/farm/hydraulic/hardware kinda place called Princess Auto. I imagine there are chains like that in the states. I don't know if Home Despot/Lowes would carry it or not.

You could try automotive DIY places, like NAPA/UAP, or Pep Boys...
 
Squidbait said:
OK, apparently Lowes does carry it... so maybe Home Depot will too!
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Be careful, I'm not sure about a "Paste" solder and it's silver content. Even some "non-lead" solder says it's got silver in it, but it isn't really what is defined as "silver solder"... I found that out when I told the building inspector that's what I used and he just laughed as he rejected my underground plumbing job.

Real silver solder is very expensive and is used mostly for making jewelry. If I recall, it has about a 50% silver content, but don't rely on that. It usually takes a torch or other high heat source to melt it.
 
Steamhead, I have some Atlas machines I converted to undertable using steel music wire. I have had good luck using hot glue instead of solder. One of the problems with solder in a case like yours, it gets brittle after being applied and cracks. The hot glue remains flexible, to a point.

Loren
 
The paste is silver-bearing solder, which makes it more conductive than standard 60:40 lead solder, but more importantly it has no lead in it, which means it's very strong.

Silver solder can range from 5% to over 50% silver content. Jewelers use the higher-content stuff, but for electronics, 5-25% is quite common, because it's got high conductivity but still melts at a low enough temperature you can use a soldering iron.
 
Hot glue...?? Gonna try that on the bench...see how it holds up. If it works OK, I'll dive under the layout and apply it to the switch machines under there...Thanks for the advice...
 
I've used silver soldering for components of wind tunnel models but as stated above , "its a torch operation due to the high melting point". There may be an electrical system that produces high enough temperature but I don't know if something like that would be cost effective for home use.
 
Solder-It will flow at 430' F. The blue part of a butane lighter's flame is about 1800' F.

No torch required, but a little butane torch flame is much easier to control than a lighter.
 
Well, I spent the better part of the afternoon replacing lost music wires and hot gluing all the other wires that had not yet failed. Let's see how this works out...Hope they'll hold...:rolleyes:

I'll make sure to use silver solder on any new switch machines before they get installed.:mrgreen:

Thanks all for your input... :thumb:
 
One thing I was taught when I was learning how to solder is that the joint should not rely on the solder to hold it together. Whatever you are soldering should have a good mechanical bond and the solder should just reinforce that bond.

In this case, the solder just won't bond to the steel wire and I'm not sure that even silver solder would do the job. You basically need to weld the two pieces together. It could be that using a high content silver solder might work, but it may not be worth the effort to find out. Using about a 50% silver content requires about a 1200 degree flame to melt the solder, making the bond more likely, but again, maybe not to steel. Also, checking the prices on the Net, I found some 56% sliver solder running almost $60 an ounce. Using the hot melt or even epoxy glue should work a lot better and is certainly a lot cheaper.
 
Don,

As far as the strength goes, I use the Solder-It paste to solder the landing gear together for my RC planes. If it'll stand up to that, it'll hold up in a switch machine linkage.

That said, it's easy to use at the bench, but if these repairs have to be done under the layout, it might not be such a good method... open flame and benchwork probably don't go together! :eek:
 
Squidbait said:
Don,

As far as the strength goes, I use the Solder-It paste to solder the landing gear together for my RC planes. If it'll stand up to that, it'll hold up in a switch machine linkage.

That said, it's easy to use at the bench, but if these repairs have to be done under the layout, it might not be such a good method... open flame and benchwork probably don't go together! :eek:
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That's good to know. My concerns were that at some temps the steel tends to oxidize and soldering anything to it is out of the question. I've not soldered steel wire much, but I've never been successful with regular solder.

My problem with the building inspector was that you had to use a higher content silver solder then available at Home Depot when burying copper pipe under cement. It was either that or eliminate the joints which is what I wound up doing.wall1
 
Maybe I could make a recommendation from what I learned in the model airplane world. Obviously, the piano wire is steel and can't be soldered directly. In the model airplane world things like landing gear are many times made of steel wire, some of it pretty big. A trick I learned was to wrap the two pieces of steel with copper wire, which can be soldered, and then solder the whole thing. Typically, this means having a lap joint with the soldered wire around it binding the two parts together. It's more of a mechanical joint, but very strong. I'm not sure this helps you directly, but maybe some variation can.
 
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