Alloy Brazing

[wesley]

Hi all ,have any of you had used the alloy brazing rods that you can just use a blow torch,to weld,wanted to join some 1/16 alloy plate together and was thinking if the brazing works ok,thanks

 

[bazmak]

The word alloy makes no sense,do you mean alum.?
If so then you can buy fluxed alum brazing rods,low temp.
that can be used with a gas torch.I have used oxy/acet but a map gas should do for small sections

 

[goldstar31]

As Barry rightly says, aluminium( and also zinc etc) can be easily 'soldered' with a fairly low powered gas torch using butane or propane.
If you had read a few of my comments here only days ago, I described using the ordinary domestic gas stove.

As for 'silver soldering', you can happily use it on steel, brass and stainless if you use the correct flux and nothing more complicated than a little methylated spirits burner. There is a world of information about things as complicated as model loco boilers published in the past with nothing more than paraffin( kerosene) blow lamps.

What is difficult is 'brazing' using metals which are cheaper and have a much higher melting point. You need additional air or oxygen to raise the heat of the flame. I certainly cannot melt some of these fluxed brazing rods which contain copper with my Propane torch but this need not be a problem with a cheap electric welding set and carbon rods.

I recall replacing a rear valance on my old Mini Cooper with such rods. I think that is a join of about 3 or 4 thicknesses of manganese steel.

It's all very school boy physics stemming from lectures on how metals were and are melted out of ore and onto People like Henry Bessemer that finally used hot air . Sounds as if I am using the same.

Heat, HEAT and how you achieve it is really up you. The Romans in North Wales extracted copper from the Great Orme using nothing more than brush wood. Copper has a pretty similar melting point to iron!

If you follow what is really history, you will be on right track

Norm

 

[Cogsy]

Copper has a pretty similar melting point to iron!

This is patently not true - Cu 1085 C, Fe 1538 C - that's quite some disparity.

 

[BaronJ]

Hi Guys,

I always found that welding aluminium was very difficult, it is extremely hard to see the point at which it turns plastic, just before it becomes liquid and falls away leaving a hole. Brass and copper is very similar. The transition point is hard to see, it takes a fair amount of practice.

 

[goldstar31]

This is patently not true - Cu 1085 C, Fe 1538 C - that's quite some disparity.

I'm pleased to record that someone is concentrating but it is an age old Trojan Horse thing- with many uses. Of course, the same old techniques practices are used whether one is sticking one metal , another metal or a mixture of metals together, it requires heat and the ability of someone to know, as Baron rightly mentions, to know when the weld pool ceases to be one- and collapses. The next trick is how to avoid it happening and there is no one that I have come across who has a pyrometer handy, it ALL has to come, not through internet learning, but plain crude and very necessary practice.

The weld pool is a curious place. Unless it is clinically clean kit will contain impurities or as we who were 'pit yakkers' something called dottle reminiscent of the bit left in a smoker's pipe. Whatever it is called, the impurities- regardless of virtually meaningless temperatures, must be brought out of the pool or face porosity.

This, I'm afraid is rarely in the text book because it is too difficult to describe. It has to experienced and , as many who are or were certified welders or whatever, will vouch.

Norm

 

[bazmak]

As Baron said alum is very difficult to weld with gas purely because
one second its there the next its gone WITHOUT A CHANGE IN COLOUR
Fluxed alum brasing rods make it easier as the weld forms at a lower temp
than normal melting point but the weld is not as strong as full melt
It is much easier to join thin section and if possible bend a slight upstand
to each end and then weld the edge.You can only try it and see.I can only
comment that its easier with a hotter flame such as oxy/acet as the flame can be flashed over to make the weld whereas with say propane it takes longer
to heat up the weld area and alum is a good conductor so the longer you take to get the weld area to temp the larger the hot area and the dreaded alum sag

 

[goldstar31]

As mentioned in earlier posting, I had success with something called Durafix Easyeld.
This did not required a flux and it was claimed to create a weld stronger than the parent metals. In the spec, it was claimed that the melting point was 7320F but I don't believe in fairies! Nevertheless, I was able to melt it on the corner of a domestic cooker ring and it would seem that my efforts were successful. I didn't do the classic stuff of testing nor did I cut through the weld and clean up and examine with one of my microscopes. Nor, was I particularly bothered to find out what the constituents and proportions went into the brew. Life is far too short for such things.

I did, however, do a dummy run on some aluminium square channel that came from one of those rotating clothes dryers. I could build up a neck and drill and tap it to do holders for grinding lathe tools.

And there, good folks, is where I left it. In a warped sort of way, there was a possible outlet in my endeavours as my late wife left me with a bewildering collection of aluminium music stands which were a ready source of bits for the Acute Sharpening System actuating arms if built up with the remains of this brazing stuff. .

OK?

Norm

 

[goldstar31]

Wesley
If it helps, it came from Chronos Tools. No commercial involvement apart from going to their previous place to buy some very thin silver solder wire. It was for a mate of the missus who was repairing clarinets and saxophones. Actually, he was an expert on acid corrosion on full size ship's engines. But I digress.

Cheers

N

 

[wesley]

Many thanks for the info,will get some an give it a try,if l do not get on with it then will stick with steel sheet an the migwelder.