Brazing Brass

Welding Techniques, Theory, Machines and Questions.

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liveaboard
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Re: Brazing Brass

Post by liveaboard » Sun Aug 12, 2018 4:29 am

I agree with Bill, you need to heat the part more.
I don't think your tip is too small, you just need to heat the part for a good long time.
A larger tip will save heating time of course, but once you get all red and melty, control is everything. a small tip is MUCH easier to control, you want to pull it away a little as melting finally happens [it always takes longer than you expect], let some heat bleed away from the work point and move it along as you fill the crack.
Definitely don't use a cutting tip! Far too big, too much heat, no chance to control the puddle.

But if you can't get O2, it's not going to happen.

John Evans
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Re: Brazing Brass

Post by John Evans » Sun Aug 12, 2018 6:24 pm

My tanks are probably older than this part. They do not even have threads for a cap. I think they are unfillable and illegal to transport.

I digress...
Depends on the tank size the 40 & 80 CF oxygen are not setup for caps. High pressure gas bottles have been around for well over 100 years, seen more than a few with dates going back into the 30s. Even seen a few with pre WW II German military stamps.
www.chaski.com

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ctwo
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Re: Brazing Brass

Post by ctwo » Mon Aug 13, 2018 9:41 am

I will call the welding shop again today and find out re-fill requirements. The tanks are small, up to the knee and thigh.

I had started writing something about this being brass and why am I not given brass rod?
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...

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warmstrong1955
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Re: Brazing Brass

Post by warmstrong1955 » Mon Aug 13, 2018 10:30 am

ctwo wrote:
Mon Aug 13, 2018 9:41 am
I will call the welding shop again today and find out re-fill requirements. The tanks are small, up to the knee and thigh.

I had started writing something about this being brass and why am I not given brass rod?
You have to have a filler rod, that has a lower melting point than the part you are brazing.
That is also, what makes brazing brass more challenging than silver soldering it. The closer the melting temps of rod & filler, the more control it takes.

Bill
Today's solutions are tomorrow's problems.

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NP317
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Re: Brazing Brass

Post by NP317 » Mon Aug 13, 2018 10:37 am

Thus my recommendation of silver soldering.
BTDT.
~RN

johnfreese
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Re: Brazing Brass

Post by johnfreese » Mon Aug 13, 2018 9:29 pm

Be careful considering a backing late. If this is a part that coordinates opening multiple doors the distance from the pin to the back of the unit may be critical to it working correctly.

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ctwo
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Re: Brazing Brass

Post by ctwo » Tue Aug 14, 2018 9:45 am

I just don't think silver solder would be strong enough, and it would be expensive as I wanted to fill in some of the distortion along the flat part that goes against the door, under the crack, and then mill it flat.

But I'm probably not going to pursue this further, unless I actually re-fab it out of steel. That is the only means I have readily available to me now.
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...

John Hasler
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Re: Brazing Brass

Post by John Hasler » Tue Aug 14, 2018 12:51 pm

johnfreese wrote:
Mon Aug 13, 2018 9:29 pm
Be careful considering a backing late. If this is a part that coordinates opening multiple doors the distance from the pin to the back of the unit may be critical to it working correctly.
After soldering/brazing the broken parts mill away enough of the back to allow for a steel plate. It needn't be very thick. This would also reduce the amount of sliver solder needed.

Silver solder is probably as strong or stronger than the original material.

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ctwo
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Re: Brazing Brass

Post by ctwo » Tue Aug 21, 2018 2:55 pm

I wanted to stick this thing together just for the sake of it and went for plain old soldering - maybe I used the wrong stuff again, but it still wasn't happening.

I used two propane torches, turned up high, and focused right in the middle of the thick part of the crack, for a full 20 minutes. The solder melted on the metal and beaded up. I continued to drizzle flux on it. Tried cleaning with SS brush. More flux, more solder, no stick. It was beading up like a fresh waxed paint job. This stuff must have lots of silica or something in it.

I gave the part back - right after the beaded up piece of solder made a tick sound and just jumped off the part and poked me in the eye - well, not literally...
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...

Harold_V
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Re: Brazing Brass

Post by Harold_V » Tue Aug 21, 2018 3:53 pm

Once you applied excessive heat to the part, there's little chance that fluxing, alone, would have yielded a clean surface. Solder won't adhere unless the base is quite clean, thus the use of a more aggressive flux (often acid type).

If you had a blast cabinet at your disposal, you could have used bead or abrasive to clean the surface, freeing it of oxides. Once fluxed, so long as you didn't play the flame directly on the area to be soldered, I expect you'd have enjoyed success, although, with soft solder, it wouldn't have been very strong.

This applies to silver solder as well. It's very important that you prepare the surface properly. If not, it won't solder well.

I commented, earlier, that the material is most likely NOT aluminum bronze. That was due to the color that showed on my monitor, however, and nothing else. If, by chance, the casting is made of aluminum bronze, you'd experience very poor results trying to solder. I've soldered aluminum bronze with success, but it's not easy.

H
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DavidF
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Re: Brazing Brass

Post by DavidF » Wed Aug 22, 2018 12:06 am

Harold, there is not a person on earth that can tell what type of brass alloy they are looking at by seeing the color on their computer monitor (there is just too many variables). That's why I suggested taking it to a scrap metal yard to have it scanned. Someone posted about the year aluminum bronze would have been more commonly used, now thats good thinking :). I questioned the part being made from brass because that just did not seem to be a good choice of materials However I did fail to look at the time line...
If you were to cast this part in a brass or bronze alloy today, what would you have used?
I have never tried to solder aluminum bronze. Can you please elaborate on what very poor results is? What happens exactly?
Never know may have to do it myself one day....

Harold_V
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Re: Brazing Brass

Post by Harold_V » Wed Aug 22, 2018 1:32 am

DavidF wrote:
Wed Aug 22, 2018 12:06 am
Harold, there is not a person on earth that can tell what type of brass alloy they are looking at by seeing the color on their computer monitor (there is just too many variables).
True to a point, but aluminum bronze lacks even a hint of red, with well aged aluminum bronze even displaying a color leaning towards black. I based my comment strictly on that. If the color balance of my monitor was off terribly, or the picture color balance was off, sure, you couldn't tell. That's exactly why I said what I did. Didn't try to second guess the material otherwise.
That's why I suggested taking it to a scrap metal yard to have it scanned.
An excellent suggestion, assuming there's a yard near, and they're willing. I suspect they wouldn't be, and if they did, the cost could be shocking, as those guns cost in the five figures. All depends on the relationship you have with the yard. Certainly a valid suggestion.
Someone posted about the year aluminum bronze would have been more commonly used, now thats good thinking :).
I'm having more than a hard time understanding why timing would be critical. Aluminum bronze isn't new, and it isn't user friendly. It isn't generally used unless required, much the same as manganese bronze, which makes aluminum bronze look like a walk in the park.
I questioned the part being made from brass because that just did not seem to be a good choice of materials However I did fail to look at the time line...
85-5-5-5 brass has been used extensively for ever. Not as common these days, perhaps, due to the lead content, and also because of the high copper content, but you can expect a lot of castings to be cast of that material, especially when a rich red tone is desired. It machines beautifully, which is also one of the reasons it has been used extensively. Aluminum bronze doesn't machine well, so it is unlikely to be used where there's any difficult machining operations unless the properties it offers are required.
If you were to cast this part in a brass or bronze alloy today, what would you have used?
Not being an authority on alloys, I may not make the best choice, but from my vantage point, if I was to specify a given material, I think I'd use silicon bronze. It's tough, machines well enough, and is readily available. I'm open to correction if that would be a poor choice. Now, on the other hand, if I was to cast it from materials I have on hand, it most likely would be cast from an alloy that is near the 85-5-5-5 I mentioned. It's strong enough for the purpose, assuming the fasteners are not pulled out, or allowed to operate with the fasteners loose.
I have never tried to solder aluminum bronze. Can you please elaborate on what very poor results is? What happens exactly?
The only issue I had with the material was in wetting. I made end caps for the manifolds for my hydronic heating system, and used what material I had on hand for the end caps. Some of it was aluminum bronze. This was several years ago, but what little I remember was it took some special effort to get areas to solder. Scrubbing with flux and a stainless brush is what I recall doing. At any rate, I was successful in making solder joints that held, and did not leak. That's dead easy with most copper alloys. Aluminum bronze? Not so much.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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