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Soldering potmetal

Greetings, I had to repair my daughter's music box. Gilded potmetal. The hinge comprises three brass tubes and a copper rod. One of the hinge tubes came off. My Radio Shack soldering iron couldn't get the thing hot enough; the box was too efficient a heat sink. I tried using a propane torch. I got a cold joint, which broke again soon thereafter. So I cooked it a little hotter, the joint drew the solder in...and then the box melted through. Filled the hole with solder. When I glued the felt lining back in, the pothole didn't show.

Then one of the legs broke off. I used epoxy this time...

So, when it breaks again: Any tips on how I can get a good solder joint with my limited equipment? Or should I skip the solder and use epoxy?

Thanks.

Reply to
Australopithecus scobis
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Reply to
Murray Peterson

Cool. Thanks.

Reply to
Australopithecus scobis

Yea, that was cool.

Reply to
Scott Moore

Potmetal can be welded or soldered, but it's tricky. There is a special solder available for potmetal. See

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I've seen this material in a hobby store (Hub Hobbies in St. Paul, MN), Caswell is by no means the only source.

The problem with potmetal is that it is extremely "hot short" as you observed. The transition from solid to liquid is abrupt, and the liquid state is very runny. The solution is to constrain or "jig" the joint so when the metal melts it has nowhere to go but where you want it to be. I've used clay, petrobond casting sand, and a blue ceramic jigging putty from Eastwood. The jigging putty works best, don't know if they still offer it or not.

Reply to
Don Foreman

Hmmm ... having just bought some Cerrobend, it pops to mind. It has a very low melting point (160F) and tensile strength about that of solder (6k). The question is - will it wet pot metal? Probably not, or we'd have heard about it. I may try it anyhow. Unless someone already has. ??

Bob

Reply to
Bob Engelhardt

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