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Old Nov 22, 2013, 04:36 PM
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"brazing" music wire L/G and Control horns

I .want to make a music wire landing gear, some cabane struts, and an elevator control horn.

I have an acetylene brazing torch I use for repairing thin lawn mower decks with minor cracks and broken handles and mounts,etc.

I have a wire bending tool and a satisfactory vise.

I can do the brazing well enough.....I'm concerned about "re-tempering" the wire , once I'm done.

When I was a youngster working in a machine shop, my boss made hardened steel dies for a local business...He filed and shaped, heated them for hours,then dunked the orange hot parts in a vat of oil.
Is it as easy as that to re-temper the music wire, with the correct oil ?

....just heat and dunk??
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Old Nov 22, 2013, 05:31 PM
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Yes and no. It needs to be red hot, and quenched. It would likely melt the brazing that you did. After it is quenched, it is hardened, then it needs to be tempered. That involves reheating it to about 200 degrees C. If you clean the wire or whatever, and then heat it till it is a straw yellow colour, you will be pretty close. Grey and you went too far. (if you brazed it and it is grey, it is likely pretty soft ) If you don't do this it will be fairly brittle. Sometimes I will heat up just the end of a landing gear axle so I can thread it. I don't bother hardening it because it doesn't turn different colours at the bend.
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Old Nov 22, 2013, 05:51 PM
Jim C Patrick
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http://www.nwrcc.com/articles/HeatTreatingMusicWire.pdf
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Old Nov 22, 2013, 10:53 PM
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If you are used to using brass and bronze alloy brazing rods then look into the lower temperature silver brazing options. There are a number of alloys that melt down around the 590 to 640F range which will prevent the music wire from becoming annealed to any great degree. So no need for reheat treating the wire, which by now you will see is impossible.

Or you can do what many generations of model builders before you have done and wrap the joint with a tight wrap of 22Ga mild steel or copper wire and use regular soft solder. The reinforcing of the wire binding around the joint ensures a good solid joint with adequate strength for all but the worst of crashes.
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Old Nov 23, 2013, 12:53 AM
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I've been doing what you say, for 'many generations' myself....

I have an idea for a specialized landing gear ,that will require brazing to accomplish...

Mr. Shattlerow made one for my 1/3 scale Christen Eagle 30 years ago, and I want to duplicate it. He has passed on, and I want to learn how to do it.

Your Silver solder suggestion should solve the dilemma....-it requires short pieces side by side at the fuselage bend, giving great strength, and minimum thickness.
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Old Nov 23, 2013, 06:21 AM
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Brazing or even Silver Soldering (Sodering) joints will melt at the temperatures required to either anneal or fully reharden Piano or Music wires. You need the whole of the wire construction to be at bright Cherry red heat, normally carried out in a heat treatment oven or furnace to attain the upper eutectic point, hold for a soaking time and then plunge into a cooling media. This part of the operation would probably crack a "Soldered" joint.

Re tempering is a lot easier and can be carried out in the domestic oven to achieve a controlled temperature soak.

Welding could work but you still have to go through the full heat treatment cycle. Might need clamping to avoid distortion and that means the jig would have to go through the heat cycle too.

Regards Ian
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Old Nov 23, 2013, 08:04 AM
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Ya, I often thought about MIG welding on the bigger wire, but didn't want to heat up the whole thing to heat treat it.
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Old Nov 23, 2013, 08:39 AM
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I'll be using 1/4 " diameter wire for all pieces, to hold up a 34 lb model (1/3 scale Decathlon)..

Since I can't do some of the recommended procedures, I'll do the best with what I have, and accept the fall-out...I have an Aluminum gear blank....I'm doing this music wire for the education.
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Old Nov 23, 2013, 09:19 AM
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"I have an acetylene brazing torch "

I would NOT recommend trying to braze and re temper the "stuff" that we get these days that is called "music wire" It ain't like the old stuff, where that was possible. The current alloys do NOT react the way we expect.

I would experiment to see what kind of radius I could get without fracturing the bend, and cold form; and soft solder.

Les
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Old Nov 23, 2013, 09:40 AM
The Junk Man
Jacksonville, Florida
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That looks like a job silver soldering would do well.

As for the strength of silver solder, I have been making my own bandsaw blades from coil stock for years and it holds perfectly under that demanding service.

Tom
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Old Nov 23, 2013, 11:15 AM
B for Bruce
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Earl, that sketch looks like a perfect candidate for a lower temperature sort of silver soldering.

What you want to do is check with the welding supply shops in your area. They are the ones which have or can get the various alloys of silver solder.

In any event the whole idea of brazing and then re-heat treating is a non starter. Because short of actually welding the wire once you heat it up to harden it the brazing in the joints will melt and flow away and your work fall apart long before you reach the proper temperature. This applies to brass brazing as well as silver soldering.
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Old Nov 23, 2013, 12:05 PM
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Grade of Solder you need is 60/40 Tin/Lead and bind the joints with tinned Copper or straight Copper wire before soldering as Bruce suggested way back. Any that are going to require a flame to melt are going to "Draw" the temper of the wire and loose the springiness.

Regards Ian
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Old Feb 20, 2014, 11:10 PM
Short bursts, Don't waste ammo
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How did you bend that 1/4 in wire?
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Old Feb 21, 2014, 12:40 AM
KE your cub.
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With a big a$$ wire bender!

How do you bend 1 inch steel reinforcing bar?
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Old Feb 21, 2014, 03:39 AM
Short bursts, Don't waste ammo
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I should have been more specific ! LOL! I was wondering what tool are you using and how do you set up to get accurate bends in the wire. I'm hoping to do this without heat treating it because I will need to solder some hinge points on it after I bend it. I need to keep the bend radius reasonably small.
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