Author Topic: Help Wanted - Silver Soldering Master Class  (Read 1122 times)

Offline FKreider

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Help Wanted - Silver Soldering Master Class
« on: January 11, 2023, 07:32:12 PM »
Hello All,

I'm hoping this is the correct place for this post!

I have some (relatively limited) experience with silver soldering, mostly small brass/bronze fittings and copper tubing for my steam locomotive. I would definitely consider myself a novice overall.

For 2023 I would like to improve my silver soldering skills and techniques. I see some really clean work here and on other forums and I am always jealous when I see the very skilled workmanship!

So the question is; does anyone know of a "master class" type of resource for learning better silver soldering techniques and skills?

I'm open to any and all suggestions - books, YouTube videos, jewelry making resources, etc. etc.

Things I would like to improve:
    • fixturing techniques and tools
    • proper application of flux and heat
    • advanced techniques such as complex soldering of built up parts with multiple components and soldering large components.
-Frank K.

Offline simplyloco

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Re: Help Wanted - Silver Soldering Master Class
« Reply #1 on: January 11, 2023, 09:00:29 PM »
I hope this doesn't sound too trite, but only two things are important. Practice, and applying enough heat! Get yourself some vermiculite blocks and surround your work with them, and fit a big enough burner to get the work red hot in  a short time so you don't deplete the flux.
Hope this helps.
John

Offline crueby

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Re: Help Wanted - Silver Soldering Master Class
« Reply #2 on: January 11, 2023, 09:45:34 PM »
Have you seen any of the Kozo Hiraoka books on building locomotive models? They have a lot of that type of information. Thats where I learned most of what I know about silver soldering and fixturing.

On this forum there is currently a build titled 'Pennsylvania A3 Switcher (Kozo)' by 'Kim' that is building from one of his books, he is going through a lot of the same learning on silver soldering that you are asking about, there are lots of posts over the last few months dealing with just that.

Other than that, its a pretty broad topic, lots of people here would be glad to help with specific questions, I'm sure. A lot comes down to practice, as John said, plus help on specific setups/tools depending on what parts you are trying to make. I don't know of a specific class or thread on just that topic, since a lot depends on what size/metal parts you are trying to do, and what tools you have.
Chris

Online tghs

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Re: Help Wanted - Silver Soldering Master Class
« Reply #3 on: January 12, 2023, 01:19:38 AM »
my biggest hint is to solder in a darkened room, it allows you to see the glow and temp of the parts better, you can see where more heat is needed and where parts are getting to hot..
what the @#&% over

Offline vtsteam

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Re: Help Wanted - Silver Soldering Master Class
« Reply #4 on: January 12, 2023, 02:00:24 AM »
Try also Tubal Caine's "Soldering and Brazing".  (The Model Engineer Tubal Caine, Tom Walshaw, not the present YouTube incarnation). It's Number 9 in the Workshop Practice series. Very reasonably priced.
Steve

Offline Jasonb

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Re: Help Wanted - Silver Soldering Master Class
« Reply #5 on: January 12, 2023, 07:30:14 AM »
The CuP Alloys book is said to be very good, written by someone who has spent their life in the silver solder business

https://www.cupalloys.co.uk/store/A-Guide-To-Brazing-And-Soldering-by-Keith-Hale-p276411652

Offline PJPickard

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Re: Help Wanted - Silver Soldering Master Class
« Reply #6 on: January 12, 2023, 11:14:48 AM »
I've done my share of silver soldering and the best piece of advice I can give you is CLEAN EVERYTHING. The last thing I do before lighting the torch is clean the parts to be joined, I use alcohol or sometimes acetone. I also clean the solder itself. After that don't touch any of it with bare hands, then apply the flux and heat. This leaves out a lot of info...but I've found the cleaning is super critical.

If you will be a CFE tomorrow we can chat.

Paul

Offline simplyloco

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Re: Help Wanted - Silver Soldering Master Class
« Reply #7 on: January 12, 2023, 01:08:21 PM »
I use this silver solder paste for much of my small fabrication work. No mucking about mixing flux to the right consistency, and clean up afterwards with a toothbrush!.
Expensive but mighty neat and effective.
John
https://www.cupalloys.co.uk/store/455-Silver-Solder-Paste-10g-Syringe-p276411691


Online tghs

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Re: Help Wanted - Silver Soldering Master Class
« Reply #8 on: January 12, 2023, 02:18:29 PM »
I get fine wire silver solder through Rio Grande jewelry supply (and other soldering supplies),, they have different alloys that will match the metals you are soldering. it does cut done on the appearance of solder lines..
what the @#&% over

Offline FKreider

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Re: Help Wanted - Silver Soldering Master Class
« Reply #9 on: February 01, 2023, 08:04:09 PM »
Try also Tubal Caine's "Soldering and Brazing".  (The Model Engineer Tubal Caine, Tom Walshaw, not the present YouTube incarnation). It's Number 9 in the Workshop Practice series. Very reasonably priced.

Thanks for the suggestion! I picked up a used copy off Amazon for less than $10 shipped!
-Frank K.

Offline FKreider

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Re: Help Wanted - Silver Soldering Master Class
« Reply #10 on: February 01, 2023, 08:08:13 PM »
The CuP Alloys book is said to be very good, written by someone who has spent their life in the silver solder business

https://www.cupalloys.co.uk/store/A-Guide-To-Brazing-And-Soldering-by-Keith-Hale-p276411652

This book seems to be the exact type of resource that I was looking for, unfortunately I cant find a source to purchase a copy on this side of the pond.

They want 40.00 for shipping alone, combined with the price of the book itself that makes for a pretty expensive book at $74 USD!
-Frank K.

Offline springcrocus

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Re: Help Wanted - Silver Soldering Master Class
« Reply #11 on: February 02, 2023, 12:16:16 PM »
Seven or eight years ago, I had never silver-soldered anything. During a vist to Simplyloco's workshop, he demonstrated how it was done on a small piece of material and sent me home with a rod of solder and a small pot of flux powder. Many thanks for that introduction, John!

After a shakey start, I practiced soldering brass, bronze and copper components together, then jumped in at the deep end and started to build the boiler for a 5" gauge Britannia locomotive. Well, talk about walking into the lion's den. The barrel alone was 6.1/8" diameter by 20" long with thirty flue tubes, then the combustion chamber and very complex shapes. There were a lot of sceptical people out there who suggested getting a commercially-made one (about 5k).

However, over the next couple of months, and with a fair bit of help from my mate Wilf, a boiler emerged and successfully passed the boiler shell test. We both learnt a helluva lot in that time, learning about controlling the heat, cleanliness and how different types of silver solder react and at what temperature. I then completed an 1.1/2" scale Allchin boiler on my own and we came together to make the third, much simpler boiler for my current build, Calbourne, another 5" gauge locomotive which I'm currently writing about.

I would offer the following to help ensure successful joints every time.

Firstly, always clean the work just before soldering. I always pickle components - copper, brass, bronze, even mild steel - in citric acid, then rinse in clean water. If using screws or rivets to hold things together, pickle those too. Some people prefer sulphuric acid but there are greater risks of personal injury if using this stuff. You can drink citric acid! Don't touch the mating surfaces after pickling. The active ingredient in most (all?) silver-solder fluxes is boron and, although it breaks down oxides, it doesn't like grease very much.

Secondly, flux everything. I use a ready-mixed flux because it takes all the guesswork out for a beginner. If you are mixing up powder, it needs to be the consistency of toothpaste or squirty mayonaisse, not as runny as single cream but not thick like gloss paint. I paint the flux on every surface to be soldered, including in the holes, on rivets and screws, BOTH sides of a joint, not just one. I use cheap, artists paintbrushes for this.

Thirdly, make sure the joints are a good fit! In the old days, it was usual to leave a five thou gap for the solder to fill but these modern solders don't work like that. Australians can still buy cadmium-based solder that are pasty and gap-filling but they can't seem to get the hang of cad-free solders because they still insist on leaving a large five-thou gap. The solder just pisses out the other side without making a joint. Somewhere between zero and one thou is the ideal gap; I have successfully silver-soldered a joint that was tightly compressed with a G-clamp but, when cut open, showed full penetration.

Fourthly, get the workpiece up to temperature in a controlled manner. I prefer to lay solder alongside or over the joint rather than dab it in when up to temperature. Molten solder flows towards the hottest point, alloying with the parent material as it goes through the joint. I always start with a gentle flame and slowly boil the water off from the flux, then start to increase the flame-size once the bubbling has stopped. Watch the flux carefully while bringing the heat up and when it starts to melt, you are getting close. At this point, I wind the flame up even more and really get the heat in. Soon after this, the flux goes clear and the work is just about up too temperature. Keep the heat going but don't be tempted to apply flame directly to the solder or the joint WILL fail.

Fifth, use the right solder for the job. I only use two grades of silver solder; 40% silver which melts at about 720o centigrade and 55% silver which melts at about 670o C. I use the higher melting point solder for bushes and other parts that need to be pre-soldered to the work and the lower temperature solder for all construction. Don't worry about remelting adjacent work if you need to join parts in more than one session, after the silver-solder melts into the job, it's remelt temperature is at least twenty degrees higher than before. This is because, as the solder flows, it alloys with the parent metal and silver ions migrate into the workpiece, effectively lowering the silver content of the solder in the joint. The lower the silver content, the higher the temperature required to melt.

Sixth, position the solder and try to let gravity work in your favour. I don't use the dab-it-in method unless I reallly have to, I always place cut and shaped pieces of solder rod on or around the joint. For example, I make solder rings to fit round the stem of bushes and rest the work on the head of the bush. If joining two edges together, I butt the pieces together, set them at an angle and lay solder in the vee. For a strap, I tip the work so that the strap is on the side of the work and rest a length of solder along the upper edge.

Seventh, and very important, apply the heat in the correct manner. It's no use trying to melt the solder with the torch, it will just turn into little balls and roll away. You must get the workpiece up to a high-enough temperature such that it melts the solder. Always try and heat from the opposite side, if doing something like a tube-plate, keep the flame around the perimeter and let conduction take the heat to the tubes. Don't get frustrated! If the solder isn't melting, you're not getting the workpiece hot enough. If your flame is at it's maximum and you are struggling to get there, stop and change to a larger burner. You can always turn the flame down. The mass of the workpiece plays a large part in choosing nozzle-size; the bigger the lump, the bigger the nozzle!

One of the extra things worth thinking about is the lighting. When I first started, I kept the lights off so that I could see the copper change colour as it came up to temperature. However, this masked being able to see the state of the flux because of glare from the flame and I had quite a lot of failures becauses things didn't get quite hot enough. I now have LED lighting throughout the workshop with 4000K (cool white) lamps and it's a much better to see what's going on. The flame loses it's glare and you can see the flux melt and the solder start to glisten. Because of that, you don't need to see the colour of the copper but you do get to see that all your solder has melted and flowed into the joint.

Make a decent hearth. There's no point heating a workpiece in a big open space because it will be radiating that heat away nearly as fast as you're throwing it in. The heat will conduct all around the workpiece anyway so completely enclose it in places that you don't need to apply a flame. Sometimes, you can just drape a ceramic blanket over the job but, for larger items I build a fireplace around it. In the UK, we have lightweight wall blocks that are ideal for the task. They can be cut with a woodsaw and are cheap to buy. Don't use those heavy bricks that come from night-storage heaters, they are designed to absorb heat and will steal that heat from your workpiece. They are useful if you need to soak something at an elevated temperature but useless for silver-soldering.

Finally, don't be afraid to stop and back away if it's not going to plan. Impatience is your enemy; if it ain't working, you've done something wrong. Stop, step back, analyse the problem, clean up, re-flux and start again. It will work the second time. And don't be a cheapskate with the flux, it's the least expensive part of the job but, possibly, the most important. Slap it on well and you're already half-way to a decent joint.

A final word about reference books. Many people, certainly in the UK, recommend K.N.Harris or Alec Farmer but I would suggest that, because they were all written long ago, nowadays they are not much use. The problem is that the materials we are using today are completely different to the ones they were using. If you have stocks of the old solders, then those books will still be relevant but, otherwise, I think you will be wasting your money if you purchase them today. Look for something that has been written in the last ten or fifteen years instead. Keith Hale in the UK might be worth searching out.

Sorry this has turned into such a long post and congratulations if you made it to the end. The old hand's will already have their own, comfortable way of working but this is what works for me. I hope it's been of use to someone.

Regards, Steve
« Last Edit: February 02, 2023, 09:44:52 PM by springcrocus »
Member of IWMES, Isle of Wight
www.stevesbritannia.co.uk

Offline Jasonb

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Re: Help Wanted - Silver Soldering Master Class
« Reply #12 on: February 02, 2023, 12:25:48 PM »
That's a pity that Keith's book works out so expensive for you.

I've just had a look on the web archive and found an older version of their site which had a lot of info in " Best Brazing Practice" which was taken down after the book was published as it contains a lot of the same information but can still be found here.

https://web.archive.org/web/20160410181506/http://www.cupalloys.co.uk/best-practice/

Offline flying fox

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Re: Help Wanted - Silver Soldering Master Class
« Reply #13 on: February 02, 2023, 12:27:57 PM »
Steve, an excellent description of silver soldering technique and practise, and I feel qualified to say that after building 31 boilers, and lots of fabrication work, although I now purchase large boilers since I am too old to heave big ones about.
The only comment I would to this excellent piece, is, for boilers of 3.5 & upwards, always  work with an assistant.
Regards
Brian Baker

Offline vtsteam

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Re: Help Wanted - Silver Soldering Master Class
« Reply #14 on: February 02, 2023, 07:36:02 PM »
A final word about reference books. Many people, certainly in the UK, recommend K.N.Harris, Tubal Cain or Alec Farmer but I would suggest that, because they were all written long ago, nowadays they are not much use. The problem is that the materials we are using today are completely different to the ones they were using. If you have stocks of the old solders, then those books will still be relevant but, otherwise, I think you will be wasting your money if you purchase them today.

Having just recommended Tubal Cain's book earlier in this post, and just this morning gone through my copy looking for evidence that anyone would be wasting their money purchasing it, or that it covers only unavailable "solders".

I see nothing written within that contradicts the normal silver brazing advice briefly mentioned above, so I'm not sure how it would hurt anyone else to read this book. But beyond the above brief generalizations, there is within it much additional useful and certainly more detailed information.

Some examples: there is detailed discussion in the book of cadmium and currently available cadmium-free silver brazing materials, also appropriate gap ranges called out by individual  specific alloys, explanations of the various alloy constituents and their properties, discussions of methods and tests you can perform, brazing procedures and sequences. And the book includes information on other (non silver bearing) soldering and brazing methods, material types, and fluxes. Almost none of this information is altered by time since publication.

Beyond that, the book gives very good technical explanations into WHY material constituent, and proportions affect the solder and braze alloys as they do, giving fundamental insights into why a joining session may go well, or not. It's not just a few paragraphs of how-to prescriptions. The book covers fixtures, health and safety,.....enough...it's pointless for me to continue cataloging the kind and amount of useful information that this small book contains. Just read it and see for yourself. The OP got it used for $10.
« Last Edit: February 02, 2023, 09:58:29 PM by vtsteam »
Steve

Offline springcrocus

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Re: Help Wanted - Silver Soldering Master Class
« Reply #15 on: February 02, 2023, 09:48:43 PM »
Oops! Seems I put my foot in it.  :-X Sorry, Steve.  :(
I have removed my reference to Tubal Cain because I've not read this publication, I just assumed it was from the same era as the other two. I still think the Alec Farmer and K.N. Harris books belong in a bygone age, though.
Regards, Steve
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www.stevesbritannia.co.uk

Offline vtsteam

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Re: Help Wanted - Silver Soldering Master Class
« Reply #16 on: February 02, 2023, 09:55:42 PM »
Okay Steve, no problem.  :cheers:
Steve

Offline Charles Lamont

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Re: Help Wanted - Silver Soldering Master Class
« Reply #17 on: February 02, 2023, 10:31:28 PM »
A final word about reference books. Many people, certainly in the UK, recommend K.N.Harris or Alec Farmer but I would suggest that, because they were all written long ago, nowadays they are not much use. The problem is that the materials we are using today are completely different to the ones they were using. If you have stocks of the old solders, then those books will still be relevant but, otherwise, I think you will be wasting your money if you purchase them today. Look for something that has been written in the last ten or fifteen years instead. Keith Hale in the UK might be worth searching out.
Harris's Model Boilers and Boiler Making contains about four pages and one table on solders and soldering. The diagram of a brazing set-up with a bed of asbestos cubes is, indeed, not current practice! We no-longer use soft solder or rivets and caulking on model boilers. But unless you just want to know about soldering, I think it is a mistake to dismiss on that basis a book that remains an otherwise sound and informative guide to a wide variety of boiler designs, basic design principles, the necessary calculations, etc, etc.

 

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