Silver Soldering Materials

[Dr_GMJNParticipant @dr_gmjn]

All, I need to silver solder some components, but don’t have any materials yet.

What’s the best way forward – buy a kit or separate stuff? Also where to buy from?

Ive got a blowtorch, presumably I can use that? I think it’s butane, not sure if propane cans can be substituted if that’s necessary?

Thanks!

[Dr_GMJNParticipant @dr_gmjn]

[Ady1Participant @ady1]

+1

cheers

[Thor 🇳🇴Participant @thor]

You should be able to buy both brazing rods, flux and a propane torch from CuP Alloys. A butane blowtorch may be enough to silver solder(braze) small items if you can make a small hearth to prevent the heat from escaping too fast.
I use a propane torch with several different burners, large burner for large parts.

Thor

[Paul LousickParticipant @paullousick59116]

The size of the burner and gas will depend on the size of the job. A butane torch burns at about 1315 deg C and Propane about 1980 deg C.

The grade of silver solder will depend on the strength of the joint that you want to achieve. The higer the percentage of silver in the alloy, the higher the strength, melting point and price. (you are buying silver)

The lower grades of silver solder that plumbers use can be purchased at your local hardware store but for the higher grades you may have to go to a welding supplier.

Paul

[JasonBModerator @jasonb]

Assuming it's for fabrication work and given your existing torch I would go with the lowest melting point alloy which is 455 and HT5 Flux as that will last longer if it takes a while to get upto heat.

The burner size is what governs the heating ability as that gives the wattage, your torch may be OK on smaller items but for something say the size of a Victoria cylinder you want 7-8 Kw which is what the usually standard supplied Sievert burnet puts out when run on Propane. If you do end up getting one of these bigger torches then you could go with 445 solder or even 430 which is cheaper but does take a bit more heating.

I would stay with HT 5 flux even with the bigger torch as it does last longer and will also work with stainless.

As for a source, CuP should have all you need in the way of solder and flux.

[Clive Brown 1Participant @clivebrown1]

Agree with all of the bove. If, as you appear to describe, your torch is a burner that screws directly onto a butane cylinder, then I'd basically forget it for useful silver-soldering capability.

You need a separate propane cylinder, with a, say, Sievert or Bullfinch torch with, preferably, a selection of burners.

[egaParticipant @ega]

Posted by Paul Lousick on 16/01/2021 05:14:04:

The size of the burner and gas will depend on the size of the job. A butane torch burns at about 1315 deg C and Propane about 1980 deg C.

The grade of silver solder will depend on the strength of the joint that you want to achieve. The higer the percentage of silver in the alloy, the higher the strength, melting point and price. (you are buying silver)

The lower grades of silver solder that plumbers use can be purchased at your local hardware store but for the higher grades you may have to go to a welding supplier.

Paul

Good to have the numbers for propane and butane.

Do plumbers really use silver solder? Possibly as a consequence of the ban on lead?

[JasonBModerator @jasonb]

Those working on Air conditioning, refrigeration etc do

[SillyOldDufferModerator @sillyoldduffer]

Oh dear, apologies to Keith of Cup Alloys, whose duplicate post I've just deleted, only to find the original gone too. Accident not censorship.

Possibly another moderator deleted the other one just as I acted! There's been an outbreak of duplicate posts recently.

Sorry Keith,

Dave

[HopperParticipant @hopper]

Posted by JasonB on 16/01/2021 10:15:41:

Those working on Air conditioning, refrigeration etc do

Not commonly these days. You need specialist CFC/refrigerant handling tickets, as well as electrical and fridge tickets, to do fridge work today. Mostly done by specialist ticketed fridge mechanics or HVAC engineers. And on the refrigerant pipework they use the higher silver content silver solder, similar to what we in model engineering have traditionally called silver solder. The hardware store soft solder used by plumbers for water pipework etc is only about 3 per cent silver and not the same thing but is labelled "silver solder" to denote it contains no lead. I would not try using that stuff on your loco boiler. But as Keith points out above, there is more to it than we non-experts generally realise.

That's the situation in Australia, anyway. I assume the UK having a similar love of ever-restrictive WHS laws is much the same if not slightly ahead of the curve.

Edited By Hopper on 16/01/2021 10:47:26

Edited By Hopper on 16/01/2021 10:48:19

[Keith HaleParticipant @keithhale68713]

We'll try again Dave ☺️

PL is misguided.

Increasing the silver content does not lead to a higher brazing temperature – quite the opposite.

Nor does it lead to stronger joints.

Where does this myth come from? Someone trying to justify the cost of the filler metal. They only have one to sell? No experience of other alloys? Lack of knowledge?

Silver solders are only used when there is no viable alternative. This is usually a technical consideration.

A properly made silver solder joint will be stronger than the parent material irrespective of the alloy used.

Weak joints are created by poor brazing practice. They are made by poor joint design, poor fluxing, and poor heating technique. Silver soldering is a very simple process albeit very skillful. Deviating from the basic principles of the process or taking short cuts will inevitably lead to problems. The quality of joints is controlled from behind the torch. No exceptions.

The Incas referred to silver as" the tears of the moon" Poor silver soldering practice should be referred to as " the tears of the model engineer"!

For more information then consult BS EN 14324 "guidance on brazed joints" or read my book which is based on the standard but embellished with 50+ years of experience in the business.

What is there to lose by doing it correctly?

Keith

[egaParticipant @ega]

Keith Hale:

Great stuff!

Did the Incas have a correspondingly poetic phrase for gold?

[Keith HaleParticipant @keithhale68713]

Yes ega, they did.

Let's keep the thread on topic. see personal message.

Keith

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Dr_GMJNParticipant @dr_gmjn]

Thanks all,

Yes, I've currently got a bottle with a screw-on nozzle with a simple regulator – I use it for DIY plumbing jobs etc.

Surely for small jobs I'd not need £120 of torch equipment as per the CuP website?

Jason – it wasn't actually for the Victoria cylinder, it was for the silver soldering required on the Hemmingway kits Myford spindle handle. Not sure what bit it's for, but presumably for fitting something like a 30mm x 40mm long boss to a shaft. Not bought the kit yet, but its says:

"There is a single silver-soldered joint for which you'll need solder, flux and a propane torch."

So that's what I want to use it for. I'm sure there will be other jobs that I'll need silver solder for – there were times when normal solder didn't hold up to machining parts that were temporarily joined, when I was making the 10V.

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Dave HalfordParticipant @davehalford22513]

There's one way you can find out, if you can get the job hot enough to get the solder to flow properly, then it's big enough. Otherwise it's not and you either need either a turbo / swirl burner or a bigger torch and remote bottle.

Personally I've always found steel much harder to silver solder than copper

[Nick WheelerParticipant @nickwheeler]

Posted by Dr_GMJN on 16/01/2021 17:18:09:

Jason – it wasn't actually for the Victoria cylinder, it was for the silver soldering required on the Hemmingway kits Myford spindle handle. Not sure what bit it's for, but presumably for fitting something like a 30mm x 40mm long boss to a shaft. Not bought the kit yet, but its says:

"There is a single silver-soldered joint for which you'll need solder, flux and a propane torch."

I wouldn't solder that even though I have the means. Step into the 20th century and loctite it.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Nicholas Wheeler 1 on 16/01/2021 18:17:35:

Posted by Dr_GMJN on 16/01/2021 17:18:09:

Jason – it wasn't actually for the Victoria cylinder, it was for the silver soldering required on the Hemmingway kits Myford spindle handle. Not sure what bit it's for, but presumably for fitting something like a 30mm x 40mm long boss to a shaft. Not bought the kit yet, but its says:

"There is a single silver-soldered joint for which you'll need solder, flux and a propane torch."

I wouldn't solder that even though I have the means. Step into the 20th century and loctite it.

I’ve used Loctite on a fabricated crankshaft (with pins), and it worked very nicely, but I’d like to try silver soldering just to have another technique available. I’ve also got some repair work to do on an old Wilesco engine, and an even older stationary engine that belonged to my Dad.

Then again, some say Wilesco used soft solder, others dont…

[Keith HaleParticipant @keithhale68713]

If loctite or soft solder will give you the results you require, then why even consider using the more expensive option of silver solder.

It's a no brainer!

As before, there needs to be a very good reason to use silver solder. If you don't have one then glue the components or rivet them. Don't waste your time or money.

Regards

Keith

[Paul LousickParticipant @paullousick59116]

Thanks Keith for setting me straight about incorect information that I had been given. Never too late to learn something new. Loctite and soft solder does not work for steam and boiler fittings that I make but will do more research on the grades of silver solder for different materials and applications.

Paul

[HopperParticipant @hopper]

I have one of those torches that clips on top of a disposable "spray can" type of bottle and it kicks out a surprising amount of heat, so its worth trying your torch on a test piece.

Otherwise, there are plenty of cheap plumbers propane torches on that auction site we are not allowed to link to. Not as good quality as CuPalloys professional jobs I'm sure but at the price probably good enough for occasional hobby use.

[Paul LousickParticipant @paullousick59116]

Why can't we say and reference ebay. It is a legitimate site with both good and bad progucts.

Many of my tools, cutters, etc are from ebay and I have had few problems. Ebay and Paypal both have a money return policy if the goods are not what was advertised.

Paul.

[Dr_GMJNParticipant @dr_gmjn]

OK guys, thanks very much.

For now I’ll ‘stick’ with Loctite, and not bother with solder.

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