un-brazing silver bars from coppper bars

Due to the conductivity of copper, you may have difficulty providing enough heat to dislodge the contacts. It's worth a try, but I'm not optimistic. I used to use a rosebud, with oxygen and natural gas, and have disassembled many of them. What I found to be effective is to hold the bar with a pliers, heat them to the point where the solder has failed, then smack the bar sharply on the edge of a large coffee can. That drops bits of solder and the contact inside the can, for best recovery rate. The solder has value as well, so don't discard what little accumulates in your container. Concentrate the heat on the contact---don't try to heat the entire bar.

Harold

Melting points Silver 1763.2 °F Copper 1984.32 °F

Copper is very good at conducting heat. This seems unlikely to work even with mapp gas. Do you know anyone with a heat treating oven? That would seem the best way to do the separation.

Wes S

Even worse is the conductivity of silver.

Why not cut the bars off, close to the silver/copper join, and then unsolder the copper bits. Should be no problem, once you get the silver hot enough. A one-oz bar might require you to build a small "furnace" or enclosure with firebrick to keep the heat from radiating away.

Or, after sawing off the copper, you could just sand the residual bit and solder seam away. That's probably what I would do.

Regards,

Bob

Hook arc welding lead to a pair of visegrips... Put copper lug in vise... Clamp visegrips to silver button... Turn on welder (set on high) and clamp ground lead to vise... You need a big welder to do this... Your button will melt off... Use gloves to hold visegrips...

Dead easy. Just get a couple of firebricks and a basic propane torch. I doubt you'll do it with a hand-held disposable cylinder, but the smaller sizes of floor-standing cylinder and a torch on a hose are cheap enough.

Conductivity is high but that's no problem at all. I presume these bars are just a couple of inches long and bolt to a long bus bar in service ? If so then you just heat up the whole thing until it's all hot enough to break the joint apart. If they do happen to be long bars, just saw them down first.

yes

sounds good... very exciting...

Have you tried just popping them off with a cold chisel and a big hammer yet? If you don't want to reuse them it might be worth a try. An air chisel might work okay too, I've never had one to play with though (shrug).

Even worse is the conductivity of silver.

It tends to work in your favor when removing contacts. It transfers the heat where it's needed, to the solder joint.

Harold