Tube to tube braceless joints

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MiBrassFS
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Tube to tube braceless joints

Post by MiBrassFS »

Those crossed tube over tube braceless joints can really be stinko. Seems like more often than not they come apart. They’re weak.

This one had been resoldered by someone at least once and it came apart again. Looked like a dirty, cold joint. It was a pain to get it cleaned up and resecured. There was the original solder and (at least) the last person’s added solder (maybe more than one attempt). They really didn’t like each other! Cleaned up and done now. I hope it stays done.

Best picture I could muster.

Clipboard Nov 10, 2024 at 3.54 PM.jpeg
Clipboard Nov 10, 2024 at 3.54 PM.jpeg (46.78 KiB) Viewed 195 times


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bloke
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Re: Tube to tube braceless joints

Post by bloke »

Good job.
I try to make the pool of solder look a little bit more like a flange than an invisible temporarily tacked place, because we all put pressure on instruments in various ways when we pick them up and when we play them. Contact joints are convenient, but otherwise I agree with you completely about them.

One other thing:
Many factories use a shortcut which involves electricity to clean up solder joints as it saves time vs. manually cleaning them up. It doesn't just clean them up past where they are intended to be soldered, but gets within the solder joints and turns them to Swiss cheese. The American Blessing factory used this process, and that's why their stuff would pop apart easier than some other stuff.
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MiBrassFS
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Re: Tube to tube braceless joints

Post by MiBrassFS »

I try to pool the solder into a pseudo-flange, too. This joint was a bit Swiss cheesy. I chalked it up to the bad mulligan solder joint, but I wonder now if Willson uses the method you mentioned and it started life behind the eight ball, too.
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bloke (Sun Nov 10, 2024 6:03 pm)
gocsick
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Re: Tube to tube braceless joints

Post by gocsick »

If it were designing the joint... I would specify a double flange made by silver soldering two thin sheets together. Then burnish to match the curvature and soft solder in place. I understand why no one does that.. it would cost 10X versus the braceless joint and requires someone with a lot more skill to burnish the flanges in tight areas.
As amateur as they come...I know just enough to be dangerous.

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bloke
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Re: Tube to tube braceless joints

Post by bloke »

gocsick wrote: Sun Nov 10, 2024 6:38 pm If it were designing the joint... I would specify a double flange made by silver soldering two thin sheets together. Then burnish to match the curvature and soft solder in place. I understand why no one does that.. it would cost 10X versus the braceless joint and requires someone with a lot more skill to burnish the flanges in tight areas.
On the original Yamaha 321 euphoniums, they did that on the fourth circuit. Soon thereafter, they turned it into a contact brace which always pops loose. I have no way to confirm or prove my suspicion, but I suspect that when they went to the plastic valve guides, the coarse threads, and all that jazz, a lot of the manufacturing of them (maybe everything other than final assembly?) went to China. Again, I'm just supposing or guessing.
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