Brazing Aluminum

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Old 02-16-05, 05:32 AM
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Brazing Aluminum

Gathering info on brazing aluminum. Found and ordered some AL Rod made by Dura-fix. In the processing instructions they refer to "Brush Tinned surface under heat, thoroughly filling the open pores". What is the Tinned process.
I will be joining two pcs of AL, a 1/4 inch square to the surface of a 2 inch "L". An explanation and suggested tips would be appreciated.
 
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Old 02-16-05, 04:41 PM
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A tinned surface is one which has a thin coating of solder already applied.

I have messed with more products like what you are trying that i care to remember.
I have returned from trade shows convinced that I discovered that I have finally unlocked the secret to joining aluminum, easily.
Realizing later that the one doing the demo also performs magic on the weekends.

Sorry. Just still ticked off at all those products still in my drawer.

The one's I have had the best suscess with are when they use a thick sticky flux. With that and a brush you are sometimes able to brush the oxides away fast enough to let the solder flow in behind the brush.

See if you can find a link to their website if they have one and I'll take a look.
 
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Old 02-16-05, 06:40 PM
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I purchased some rods at a swapmeet.

Aluminum oxidizes very-very fast.
First clean the area with a stainless steel brush.
You, coat / tint the area with the rod then use the stainless steel brush to clean the area a second time using heat.

The brushing breaks up the oxide, helps the rod stick better.
The tinting helps prevent re-oxidization while you are working at the opposite end.
I try to rub/push the rod on the metal at the same time to break up the oxide.
--------------------------------------------------
98 % of the people don't get the base metal hot enough, and the metal just falls off.

What I do is heat the metal, then move the flame away and rub the rod on the metal to see if the base metal can melt the rod without the flame.
If the base metal can melt the rod without the flame, you know its at the proper temperature.
 
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Old 02-16-05, 07:32 PM
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An old welder at work let me watch him heli-arc alum. We were constantly breaking alum brackets and fixing them. What he showed me was how any dirt (impurities) was attracked to the weld.

One day I sprayed a prepared joint with electrical contact cleaner. I really hosed it down. I didn't tell the welder what I'd done. He stopped after the first pass and wanted to know what I'd done. At first I just told him the usual, hogging out a groove with a super shear file. He told me he could see the cuts from the file but I'd done something different because there wasn't any dirt. The repairs got better, which meant less work for me.

I've tried the alum rod with propane torch. About the time I thought it was ready, I had a puddle of alum on the floor. They make it look so easy on those soda cans.

I spent 3 hours in a Condor basket with this same old welder cutting a bearing for a 4" shaft out of an alum housing. All I could think of was my puddles of alum on the floor. I just knew I'd never get another bearing in the unit. When he finished there wasn't even a discoloration on the machined surfaces. I never once doubted anything he did or said from that day on.

I wish you luck with the rod, just practice a lot before using good metal.
 
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Old 02-17-05, 04:32 AM
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GregH
This is the web site: http://durafix.com
Must one make a groove or chamfer on both pcs of alum in order to join them?
Or can one butt join the two after cleaning and tinning?
 
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Old 02-17-05, 04:35 AM
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PegLeg
I'll try some of that electrical contact cleaner. Wonder if carb or disk brake cleaner will do the same job?
 
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Old 02-17-05, 04:48 AM
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GWIZ
Thanks for your input!
My only past experience has been a little back yard steel arc welding, dune buggy type and copper brazing which I learned in my High School metal shop classes. Alum will be a new experience for me.
So, guys I really appreciate all your input.
 
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