Silver Solder - which one?

wrote:


Would it hold enough pressure to make a decent boom, or more like phffffffft! Gerry :-)} London, Canada
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Well I've built two with lead/tin solders. For low pressure and low temperature, there's nothing wrong with it. These were small Newcomen engines, fired by camping gaz burners.

All large firetube boilers have a "fusible plug" in them at the top of the firebox. This is a replaceable screw fitting with a hold drilled through it, filled with soft solder. If you let the water level drop to expose the plug, the heat melts the solder and it vents into the firebox. Rarely enough to affect the fire, but it's pretty noticeable and it lowers the pressure. Although there's no mechanical stress on this plug, it demnstrates that there's no inherent problem running soft solders at boiler temperatures.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Abrasive sez:
"> Soldering a boiler with tin based solder, as someone suggested, ... yeah

Boooom, yer ass! Tell it to the folks at PM Research. I have 10 or 12 hours steaming time on a PMR boiler, riveted and sealed with 96% tin, 4% silver (silver bearing solder) and no "Boooom" so far. How long does Boooom take?
Bob Swinney

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
John Hofstad-Parkhill wrote:

Judging by the responses you've had it seems to me that there is a terminology problem here. I reckon your documentation originated in UK where silver solder is the name given to a hard solder which is an alloy of copper, silver and other metals. It has a melting point of around 600C or more and is comparable in strength to brazing brass. It is _not_ the same as the lead bearing solders that can be melted with a soldering iron. The proper (UK type) silver solder needs a torch to melt it - you can use air/propane or air/butane, but oxy/propane is also used. You also need a special flux. The hallmarking quality silver solder used for jewellery is a similar product, but has rather more silver in the alloy and is, consequently, more expensive. The hard/medium/soft refers to the melting points, but even soft melts at around 600C or more. Definitely not soldering iron territory.
--

Regards, Gary Wooding
(To reply by email, change feet to foot in my address)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
9. Gary Wooding Jan 14, 3:32 am show options
Newsgroups: rec.crafts.metalworking
author Date: Sat, 14 Jan 2006 08:32:52 +0000 Local: Sat, Jan 14 2006 3:32 am Subject: Re: Silver Solder - which one? Reply | Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse
John Hofstad-Parkhill wrote:

Judging by the responses you've had it seems to me that there is a terminology problem here. I reckon your documentation originated in UK where silver solder is the
name given to a hard solder which is an alloy of copper, silver and other metals. It has a melting point of around 600C or more and is comparable in strength to brazing brass. It is _not_ the same as the lead bearing solders that can be melted with a soldering iron. The proper (UK type) silver solder needs a torch to melt it - you can use air/propane or air/butane, but oxy/propane is also used. You also need a special flux. The hallmarking quality silver solder used for jewellery is a similar product, but has rather more silver in the alloy and is, consequently, more expensive. The hard/medium/soft refers to the melting points, but even soft melts at around 600C or more. Definitely not soldering iron territory.
I beg to differ with your terminology. Soldering, by definition, is a bonding alloy that melts at a lower temperature then the base metal. Hard solders melt at brazing temperatures, soft solders generally below 600 degrees F. Jewelers silver solder comes in hard, medium and easy grades to allow consecutive jointing operations on intricate pieces. Bugs
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Gary Wooding wrote:

My "hard" (#1 high temperature flowing) silver solder melts at 860 degrees C. I got it from Degussa in Germany. I also get solders from Hafner in Germany.

Thank you.
--
Abrasha
http://www.abrasha.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
You may find some useful info on the Johnson Matthey site http://www.jm-metaljoining.com/shared/frameset.htm?/products/soft/fluxes/introduction.htm
They make a lot of the silver solder used by model engineers in the UK such as easyflo 2.
John Hofstad-Parkhill wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 13 Jan 2006 16:36:12 -0600, John Hofstad-Parkhill

There are several.
First of all, the older recipes included cadmium. This is great (metallurgically) but it's toxic as anything. So schools ditched all their cadmium silver solder a few years back - eBay bargains are still to be had ! Incidentally the flux is nasty too.
Secondly, there are different grades, with different melting points. If you're doing boiler work then you often need to use several of these in turn, so that lower temperatures ("softer") don't melt the joints you made earlier with the harder solders.
In general, use the hardest silver solder you can get away with. Less silver, so it's cheaper. Low temperature or colour considerations might force you to a lowertem perature one.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
John Hofstad-Parkhill wrote:

All solder used in the jewelry industry to solder jewlery is "hard" solder, i.e. it does not contain tin.
The terms we use, hard, medium, easy are really misleading. More appropriate might be high, medium, low as refering to the temperatures at which they flow.
I have marked my solders 1, 2, and 3 as in work flow, where my number 1 solder is used first in the process, and has the highest flow tempreature (hard). Number 2 is medium, and #3 is easy.
For silver I have 4 different solders. Again, these are all hard solders and do not contain tin.
In case of the boiler for instance for your steam engine, i would use the highest temparature solder that the metal you are soldering would allow. I assume you are making the boiler out of copper. That can be soldered with a "hard" of "medium" silver solder. I would not use a tin based solder as one of the posters has suggested, especailly for a boiler.
--
Abrasha
http://www.abrasha.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Well, I at least don't feel bad now about not knowing the answer.
I appreciate the responses.
I should have been more specific. I build model steam engines. I do not have plans to build a boiler.
I have a boiler - which I may visit someday, but am quite happy running the machines on compressed air. I am fully aware of the potential hazard of live steam. I'm not afraid of it, nor am I afraid of my table saw. That does not mean I wouldn't be careful.
As far as solder -vs- brazing, I believe I understand the semantics. I was using terminology that I find common in nearly all the literature I read about live steam model building, it's nearly universally called "silver soldering", and that's what I meant.
John Hofstad-Parkhill said the following on 1/13/2006 4:36 PM:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snip----

And I feel you used the term correctly. I'm far from a weldor, but I get the impression that there's a serious difference between silver soldering and brazing. Silver solder will follow a heat source, and flows like water. I'm not convinced that brazing works similarly.
I've been in the machine trade since the late 50's, and have always heard the process referenced as "silver soldering".
Works for me.
Harold
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harold and Susan Vordos wrote:

As mentioned previously, there is a terminology problem here. Here in UK the term "soldering" refers to the process of joining metals with another metal having a lower melting point; in contrast to "welding" where metals are joined by melting them, and possibly adding a filler of the same melting point. We (meaning us in UK) recognise soft solders as those alloys containing lead/tin and hard solders as those that do not. Soft solders can be melted with a soldering iron, hard ones cannot. One particular type of hard solder is brass. It was once very commonly used to join iron or steel, and the process was known as brazing. Brazing is simply soldering with brass. The melting point of brass is high enough to make it unsuitable for joining copper or brass items, so another type of hard solder was developed that includes silver. This lowers the melting point so that it can be used to solder copper or brass. It is just about as strong as brass, but the silver content increases the cost considerably. Brazing and silver soldering are simply hard soldering; soldering with soft solders is known as soft soldering.
In USA it appears to be different in that all hard soldering is known as brazing, and all soft soldering is known as soldering. That's how I see it anyway.
--

Regards, Gary Wooding
(To reply by email, change feet to foot in my address)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 14 Jan 2006 22:59:24 -0800, "Harold and Susan Vordos"

You've been working with metal longer than I have, and I'm an amateur at metal while you are a pro. I'll bet I could learn a lot as an apprentice in your shop and I bet I'd enjoy doing so though I strongly doubt you'd tolerate my retired-ass appetite for work or hours.
I'll still brashly note what I've learned, or think I've learned, about the subject at hand.
Silversoldering is generally the same as silverbrazing, Harold -- which can be quite different from brazing with "brazing rod" like bronze or nickel-bronze. My experience is that the latter materials don't follow the heat worth a damn, though do not profess to be a pro. I seldom use them for that reason. I haven't done a bronze or nickle-bronze joint in half a decade. Pennies of cost per joint don't concern me a bit. I'm an amateur. I don't make my living working with metal.
Many if not most or all silverbrazing alloys do follow the heat source. I use that property routinely as a matter of technique. The follow is a matter of fluidity of the melted alloy and it's abilty to wet the parent metal in both brazing and soldering.
The low-temp materials are not regarded as silversolder but rather as silver-bearing solder May seem like a nit, but big difference. Sticking stuff together with silver-bearing solders at below 800 F is definitely soldering, but silver-brazing at temps above 800F is also often referred to as silversoldering -- and the materials used to do that are often referred to as silversolders.
Brazing and soldering are similar and differentiated from welding, in that the parent metal is never melted but is alloyed at lower temp with the joining material. The primary or only difference between brazing and soldering, as I understand it, is a matter of temperature: soldering is below 800F, brazing is above. I know of no basis for this apparently arbitrary boundary, but it seems to be accepted -- if confused by the common practice of referring to what is silverbrazing by this definition as silversoldering.
The remaining sanity in this mishmash is that soldering with lower-temp silver-bearing solders is very seldom regarded as silversoldering. It's just soldering with an alloy that contains a bit of silver.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 15 Jan 2006 04:54:13 -0600, Don Foreman

You can also weld without melting the parent metal. Bronze welding uses exactly the same base materials and filler rod as brazing, but the technique is different. In soldering and brazing the overall workpiece is heated and capillary action causes the solder to flow into place. In welding (and bronze welding) the technique uses a more narrowly applied heat source. In bronze welding the cuprous filler rod is melted into place without melting the base metal (probably steel) and this gives a fillet with the typical "stack of dimes" look, not a smooth capillary fillet.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snip---

Hours? Like late night?
If you only knew! <g>
We generally get to bed well after 4:00 AM. When I was actively machining, my best hours were late night/ early morning.

-------snip lots of good stuff---

Yep! Hardly the same thing.

As I noted elsewhere, the one big difference between soldering and brazing (each "one and the same") is silver solder's limited ability to fill gaps and build beads. Don't know that it makes much difference in terminology, but it sure does when you're the guy trying to build a filet with silver solder, or bridge the gap when you screwed up on one of the components.
From all appearances, the terminology on this subject has been blurred for years. I have in my possession a large coil of 1/16" silver "solder", tag still intact, which clearly states that the product is "A low temperature brazing alloy". It's 54% silver, according to the tag. Bottom of the tag says United Wire & Supply Corp. Providence, 7, R.I. Providence *7*?
We were all pups when this stuff hit the market.
Harold
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Harold you will find a great deal of smoke and not much light on this issue.
But the general consensus is, that the following terms are indeed interchangeable and mean exactly the same thing, from an adhesion standpoint:
Brazing
Hard soldering
Silver soldering
Braze welding
The mean the same thing, basically joining two similar or dis-similar metals using a filler that melts above 800 degrees, and does not melt the parent metal.
You will find a great many folks who claim that one of the other of the four terms above are indeed separate and distinct and describe different processes. If you do, then press them to tell you exactly what is different between, say, brazing and sliver soldering. Or braze welding and brazing. Or hard soldering and sliver soldering. Etc.
If the filler metal goes liquid below 800 degrees, it's soft soldering.
If the parent metal melts, it's welding.
Jim
--
==================================================
please reply to:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

What's a degree ? Reamur ?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harold and Susan Vordos says...

get
Chuckle!
Which is becoming quite obvious!

I can provide one difference. Silver solder does not build up in similar fashion to bronze brazing.. Who amongst us hasn't seen some serious "beads" of brass built up on cast iron? Try that with silver solder. Doesn't work, nor is there much benefit in doing so, anyway. . Joints for silver soldering are generally set up quite precisely, due in part to silver solder's limited ability to fill.

Thanks, Jim. I see it pretty much the same way.
Harold
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You can build up silver solder if you keep the temperature below the flow point. Even the handy and harmon ez-flow does that, when I'm flowing a joint I like to deposit a tiny ball of solder on the workpiece. As the heat builds the flux flows out, then the ball beads up and sticks to the work. More solder added at this point will look just like the brass welding rod you buy at the hardware store. Chunky.
Instead what I do is wait till the ball flows out, then the whole thing is up at temps and the joints runs nicely. It doesn't fill, but it sure does flow. The man that taught me silver soldering told stories about brazing gun barrels during ww2. They used to press in the liners, get the entire thing hot, and wipe the one end with the solder. The other end five feet away would show the ring of solder appear all around, if the joint was done right.
But the brass rod sold at the hardware store can be used to to flow out, but it has a wider eutectic range. It's easier to hold the part such that you can build up large beads like you mentioned. I've never found joints like that to be terribly strong so I prefer to keep on going and flow it out more.
The difference is in degree only I would say.
Jim
--
==================================================
please reply to:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

And there are silver solders formulated to make a big fillet. You'll see references to them in British publications from time to time. They've been used for building custom bicycles and even for building some race car spaceframes.
I have some brand names here but I can't go looking for them.
-- Ed Huntress
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.