Got asked if I could braze on some brass to tap new threads.
It’s for a busted derailleurs hanger.
Would it be strong enough?
Thanks
if I understand correctly, these are the threads that the RD hangar retaining bolts screw into?
is the hangar ALSO retained by the axle or QR skewer while in use?
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What I understand is that on an older steel frame the hanger threads are beat.
They asked me if I could re thread it , with adding some brass a d retap after.
That’s a pretty common repair. Getting the threads in there so the mech screws in square isn’t trivial though. Try and setup something clamped to the inside face of the dropout to give you a reference.
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Thank you, this gives me some confidence to do it.
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ah the actual derailleur threads; that’ll be fine.
id also suggest to make or buy a guide to make getting that tap started straight a simple task.
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These are a better solution in my opinion.
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Thanks, @KPacenti . Forwarded your suggestion. The cyclist is going on a trip next week. I wait what he chooses
Note: The wide ones are typically for aluminum frames, the narrow ones are typically for steel frames.
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Do you braze them or just tighten it down?
They’re made to be just tightened by the derailleur. I have silver brazed these in the past too if it seemed to make sense with the repair (needed repaint anyway etc).
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You drill out the derailleur hanger to fit the OD of the dropout saver. Slip in, and tighten down with the derailleur bolt.
If I were going to add braze filler and re-tap, I’d use nickel-silver (NS for short). It’s stronger than brass, in fact likely stronger than the steel the dropout is made of.
In case you don’t know, NS contains zero silver, the name comes from the color, I guess. Dumb name. It melts at a slightly higher temperature than brass, but you can use the same flux as for brass (what the industry calls bronze or LFB).
I don’t advise completely brazing main frame joints with it, but it’s excellent for repairs that need high strength. It’s often been used to replace a broken tooth on a gear in machinery, like a lathe. Build up some NS, then re-machine that one tooth (easier than re-making the whole gear), or even hand-file it.
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I brazed a bit of nickel silver today on the DH.
Looked good( didn’t take pictures)
Deliverd it back to the bike shop to re thread it. Didn’t hear back yet, keep you osted
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I have a couple of them. OP, ping me if you want them.
I heard back from the bike shop. The threading went smooth and the bike and rider are on their way.
Thank you for the tips
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