I've tried. >:( >:( >:( And now it is really getting to me. >:(
I have solder and flux from a plumber mate and at the moment I'm trying to solder nice thick 3mm wire. I'm putting the flux on both parts, placing them in position on a firebrick, getting them warm, dabbing on the solder and watching it melt through to make a nice join... and then, within anything from straight after it is cooled to a week later, the joint has failed. Why????? Is it me, is it the solder? ??? Would I be better off with silver solder? Is what I'm making too big? Though I don't see why copper solder, which is designed for copper and used by plumbers, would be any different. And surely plumbers solder big pipes ???
All I know is that we always solder copper with silver solder at class.
Linda x
The problem with copper brazing rods is that they're designed to melt at slightly lower temperatures, which makes them intrinsically weaker. Add to this their reluctance to flow well and you have a problem.
What you're describing sounds like the solder is melting OK, but not actually bonding the copper. Have you got any gaps between the two pieces? This is usually the problem, as solder will not fill a gap permanently, although it may appear to.
If it's for anything that's going to take any real use, I'd use silver solder and either file back or plate the join.
i always thought the copper solder was for brazing or welding not specifically for using with a torch although i think you can do it will a low heat, when they use it for pipes the pipes go inside each other so the copper solder is performing more of a seam rather than a join if ya get my meaning
Aha! Thank you, I think that is definitely the answer :)
The wire is at right angles to another piece of wire and I'm trying to fill, in effect, the gap - I'd assumed the solder would bond the copper but it obviously isn't and now I understand why. :)
I'll try again with silver solder... ::) ::)
If the silver solder doesn't work have you tried electrical multicore solder? That tends to have tiny holes running through it that are filled with flux, but you still need to be soldering mechanically strong parts. It'll fill some small gaps, but it's best to have everything really tight as it only really helps everything stay in contact. With it you need to heat the copper, not the solder (about the only tip I remember from my days at college)
At last a question I might be able to help with. I'm to new at glass to be much help there but I was a metal smith for years before going back into IT.
Mizgeorge is correct in saying that the solder seems to be filling the gap between the pieces. The strength in a soldered joint (or braised for that matter, just soldering at a higher temp LOL) comes from three things:
1) The size of the gap between pieces. The smaller the gap then the stronger your joint.
2) The surface area that the joint has. The surface area between 2, 3mm pieces of wire where they actually touch is not great. Unless you have flattened the curve of the wire so you have flat areas touching, you really don't have much area to hold there. Even then you will not get what I would call a strong joint with soft solder.
3) The filler metal you are using. Normal solder is made of inherently soft metals, silver solder is obviously stronger.
You don't really say what kind of solder you are using but a simple T joint between 2 copper pieces will never be very strong. The standard plumbers stuff (as you said) if used right is incredibly strong. Check out the lanterns on the roof of Hogworts main hall in the second or third Harry Potter film. The company I worked for made those and they stood over 2 meters tall. All held together with soft solder.
Now if you wanted a really strong joint we could start looking at GTAW (TIG) welding. Now that is fun......