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I was trying my hand at fixing a damaged euphonium, just trying to see what was possible, and this required annealing the bell a lot. I noticed some solder would melt out of the bell rim while annealing with a torch, and because I was focused on something else and it was a $10 instrument I just kept going.

Is this a common construction for euphoniums and tubas? It seems like the rim is rolled and isn't going to actually come off. Is it possible to get solder back into the rim after annealing? Maybe it would keep the rim cool enough if it was in a shallow pan of water during annealing?

The biggest problem is that the wire inside the bell rim often is steel.... not brass. Some folks try to fix a 'buzzy' rim by running solder into the rolled rim.

It's virtually impossible to get what's inside the bell rim clean enough to make solder work.... even if the wire is brass.

Miraphone, for example, uses a steel wire that has some sort of coating on it so that solder will stick to it. Once that wire has any age on it... you cannot resolder it.

Question.... why are you annealing any more of the bell than the area where the damage is? There's hardly ever a reason to anneal the entire bell and rim.

I wish they would use a brass wire instead of steel, and solder it in at the factory.
No more buzz and rattle on old banged-up tubas!

I was annealing by heating up to glowing (1000+ F) and maintaining for about a minute. Working on the bell throat, the bell rim got plenty hot.

Interesting that annealing is not often considered necessary, I was looking at severe creases and trying not to make tears. It was also easy to work the metal after annealing.

TheGoyWonder wrote:I was annealing by heating up to glowing (1000+ F) and maintaining for about a minute. Working on the bell throat, the bell rim got plenty hot.

Interesting that annealing is not often considered necessary, I was looking at severe creases and trying not to make tears. It was also easy to work the metal after annealing.

Way too hot. Next thing you know, you'll have a big hole in it.

There are many methods of removing creases without heat, like gently lifting the flap with a burnisher, which is a favorite.
Burnisher use is a nearly lost art among many modern repair techs. There are still a number of shops that do it well, but they are generally staffed with old-timers like myself or younger folks who have received great tutelage and practiced many hours refining the art.

Daryl