Silver solder or braze

This topic has 13 replies, 8 voices, and was last updated 20 January 2011 at 20:35 by Bowber.

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19 January 2011 at 09:54 #62767
Eric Cox
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@ericcox50497
When building a boiler or fastening two components together do I use silver solder or braze.
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19 January 2011 at 09:54 #5365
Eric Cox
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@ericcox50497
19 January 2011 at 12:53 #62787
JasonB
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@jasonb
Silver solder, though if you are from the US it would be called “silver braze” would be the best option.

You can use Brazing also called bronze welding to join materials together but best not on a boiler as some of the brazing rods react to steam over time. It requires more heat than silver soldering so you really ned oxy-acetalene or at a push carbon arc rods on an arc welder, I think its also possible with tig using a specific rod.

Jason
19 January 2011 at 13:06 #62789
Richard Parsons
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@richardparsons61721
Which to choose, silver solder or brazing? It all depends on which metals you are joining together. What you have to know is the melting points of the materials involved. Copper has a melting point of around 1083°C. Brazing rods have a MP about 900°C, a bit too close for comfort, but if you are doing a furnace braze you could do it if your thermostats are good. What about brass? Well brazing rods are an alloy which is brass, so you would use a lower melting point rod. Probably silver solder out of choice

Steels, I often braze mild steel. A well made braze has some 80% the strength of mild steel.I have also brazed cast iron but you have to pre-heat the whole casting before doing this and let it cool down very slowly.

Special steels are designed to be brazed.One I think is Reynolds 853 (I may be wrong with the number) when brazed does not go brittle which it can do when welded.

Stainless Steel, I believe that it is illegal to braze or silver solder stainless in the U.K.The Gnomes of Elfin Safety do not like it.

Edited By Richard Parsons on 19/01/2011 13:08:09
19 January 2011 at 13:17 #62790
Richard Parsons
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@richardparsons61721
JasonB our postings crossed. I use Propane/Butane and compressed air for brazing it works well but like Oxy Acetelene you need a carburising flame.

There is a sort of myth about hot watwer disolving the zinc in brazing rods.I buy rods which aregauranteed proof against that problem.
19 January 2011 at 18:17 #62808
Bowber
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@bowber
I was always told “I’ve told you a thousand times is Bronze welding, brazing is silver soldering!”

Then I’d be clipped round the ear

Silver solder is good for close joins, so parts with a free sliding fit or close together etc can be silver soldered with the solder working it’s way through via capillary action.

Parts that don’t have a close fit will need to be bronze welded or brazed if you want to call it that.

Reynolds did make tubing for bronze welding I think it was 731 though and they make bicycle tube kits for custom made bicycle manufacturers with the same properties.

I think we used sifbronze mainly with a gas fluxer, better than powder flux as it didn’t run off down the tube with the braze following it.

I just use a TIG now as the gas bottles cost too much to keep the rent on these days for hobby use.

Steve
19 January 2011 at 19:02 #62810
KWIL
Participant
@kwil
Reynolds 531 Tubing was the start of it.
19 January 2011 at 20:08 #62814
Speedy Builder5
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@speedybuilder5
Hi Richard P – Silver soldering stainless steel – Illegal ??

Not so sure about this advice.

Looking at Johnson Matthey’s latest information:-

Their chart shows the Silver-Flo range of silver solders being suitable and

the use of Easy-Flo silver solder flux with Tenacity-5 for larger SS parts requiring extended heating cycles.

The silver flo range is Cadmium free (Cadmium bearing silver solder is not illegal, but not advised).

Hope this helps.
19 January 2011 at 20:12 #62816
JasonB
Moderator
@jasonb
I’ve got a nice 531 smooth fillet brazed mountain bike, my uncle was a frame builer. He was certified to work with all their tube sets (and Colubus)having had test joints approved.

J
20 January 2011 at 00:22 #62830
Nicholas Farr
Participant
@nicholasfarr14254
Hi,
brazing is joining two metals with hard solder that has a high melting piont, and having a gap of between 0.04 and 0.20mm. Silver solder being one of them.

Braze welding has a higher temperature and uses brass filler rods, of which there are many types.

Brass or bronze welding is as it says it is, i.e. the welding of brass or bronze.

Richard, when using oxy-acetylene you should use a soft neutral flame for brazing. A slightly oxidising flame may be used, and is preferred when braze welding or when welding brass or bronze

.

A carburising flame should be used for hard facing and when welding cast iron, using cast iron filler rods.

Regards Nick.

Edited By Nicholas Farr on 20/01/2011 00:23:03

Edited By Nicholas Farr on 20/01/2011 00:25:29

Edited By Nicholas Farr on 20/01/2011 00:28:05

Edited By Nicholas Farr on 20/01/2011 00:28:57
20 January 2011 at 00:22 #62831
Nicholas Farr
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@nicholasfarr14254
Sorry double posted.

Regards Nick.

Edited By Nicholas Farr on 20/01/2011 00:24:33
20 January 2011 at 08:53 #62836
John Olsen
Participant
@johnolsen79199
I got a lot of fun as an 18 year old trainee watching another trainee try to braze a nipple onto the end of a cable for a scooter. He would turn up a cylindrical brass nipple, cross drill it for the wire, then take it to the welding bay and try to braze it onto the cable. Annoyingly, just as it all seemed to be getting hot enough, the nipple would go and melt on him. He tried this several times before somebody took him aside and clued him up as to what the problem was.

regards

John
20 January 2011 at 09:12 #62839
KWIL
Participant
@kwil
Nick, when you have to edit, you can also edit out your previous “Edited by….” as well !!
20 January 2011 at 20:35 #62888
Bowber
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@bowber
Posted by Nicholas Farr on 20/01/2011 00:22:04:

Hi,
brazing is joining two metals with hard solder that has a high melting piont, and having a gap of between 0.04 and 0.20mm. Silver solder being one of them.

Brass or bronze welding is as it says it is, i.e. the welding of brass or bronze.

I can only go by what I was taught, I’ve still got the twitch Maybe the ringing in my ear was why I miss heard.

Steve
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