silver brazing alloy

nedmin

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Anyone know a supplier of Eutectic silver brazing alloy,in small quantities, the cat. no. is 1020XFC.I can get a box full but it comes out at about £150!! Find its very useful when you want to fix brass steel or even stainless.It can be used with a propane gun and is very strong.Or are there another 3 out there and we could split a box?
 

Norman_E

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Model Engineers use it for making copper boilers. (I have done so) There are lots of different grades, with various melting points from about 640 degrees C upwards. All grades will need you to use a propane torch like the Siefert range, butane simly does not give enough heat. You really need a different grade for stainless than you would use for copper and its alloys. Try the model engineering suppliers like Chronos in Dunstable ( www.chronos.ltd.uk )
Bear in mind that whilst a silver soldered joint in copper is as mechanically strong or stronger than the parent metal, this is not the case with stainless steel, which is usually best joined by welding if making any load bearing structure.
 

nedmin

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thanks for your advice,I see from the write up on the Eutectic box its an alloy of copper,tin,silver and zinc. I butt brazed some 1inch mild steel square tube into a boarding ladder and it is tremendously strong.When you braze stainless it "runs" into the stainless like solder onto clean fluxd copper.I have never used anything as good before.It has its own covering of flux.
 

VicS

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I bought some "All pupose bazing rods", flux coated siver alloy brazing rods for steel, stainless steel, brass and copper some years ago from B&Q. There were only two, maybe three, in the packet. They did a range of similar rods for different purposes but I dont know whether they still do.
 

Norman_E

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Brazing rods designed for use with an electric welder are quite different from silver alloy brazing rods for use with flux (usually borax based) and a propane torch for heating. The very localized heat from an electric welder can cause distortion, and poor joints often result in amateur use. The propane torch gives much more even heat with the metal to be joined being raised above the melting point of the brazing rod before it is applied. This gives strong and neat joints provided the right flux is used and the blowtorch is big enough to heat the job . My Siefert set has interchangeable nozzles fron a tiny one less than half inch diameter with a pinhole jet up to a monster that puts out a roaring three foot long flame capable of getting a 6 inch diameter copper boiler shell up to bright red heat for brazing in the tubeplate..
 

bdsweeting

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Check your local area for refrigeration/aricon wholesalers. They stock that type of brazing rod and you should be able to pick up small quantities, or try the next aircon service van driver you see !!
 

cliff

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B&Q used to have both MMA rods and flux coated wire for use with a gas burner. B&Q also do the little MAPP gas/Oxygen torchs and the mini cylinders - great for small jobs and even hot enough to weld thin sheet upto about 3mm.
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Norman_E

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A lot depends on the size of the job. Those little MAPP gas / Oxygen torches get a high flame temperature, but total heat output is small compared to a big propane torch fed by a big (at least 13KG) cylinder. A big mass of metal will conduct the heat away from the joint fast, and will need a big torch (or even two torches) to cope. For boiler work the coated rods are unsuitable. The technique is to flux the areas to be joined, with powder flux mixed to a paste with clean water, assemble the parts and heat till the flux melts and the metal glows red, then apply the brazing rod which will immediately melt and flash into the joint by capillary action. The torch should not be played on the rod to melt it, the heat of the parent metal should do that. It is a good idea to dip the end of the brazing rod into the flux paste before touching it to the job.
 

nedmin

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many thanks everyone.I have tried different makes of "silver solder" over the years but the eutectic one seems the best. I have E-mailed Eutectic to see if there is a supplier of small quantities. I will let you know how I go on.Thanks again.
 
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