Silver Soldering

[dnp101677]

I am working on an engine that requires a fair amount of silver soldering. I was wondering if someone could point me in the right direction in the way of supplies. I suppose I'll need everything; although I have a propane torch, but I don't know if I need something special or not.

It would be nice to be able to find a kit somewhere to get me started. Also, if anyone knows of any websites or posts on this site that explain (on a beginners level) how to do the actual soldering, that would be great too.

I'm really at a loss here until I can get this stuff figured out. I keep coming up with electronic soldering supplies and directions online, but I think what I need is a little different. I figured for sure someone here could point me in the right direction.

Any help would be much appreciated! Also, I'm in the US.

Thanks,
Dan

 

[Deanofid]

I do a fair amount of silver brazing/hard soldering, and use these guys for most of my supplies:
http://sra-solder.com/section.php/90/1

Get 45% or 56% wire in a rather small diameter. An .031" diameter wire is good for many applications.

A lot of people have trouble with silver brazing because they don't know what flux to buy. Get this:
http://sra-solder.com/product.php/6073/96

There are a number of posts here on silver brazing. Some of them contain some controversy, because silver brazing and proper fluxes are called different things in different countries. You will still be able to glean a lot of info from them. Try searching on "silver brazing", "silver solder", "hard solder", "flux", etc.

 

[Ed T]

For bit of cross pollination you can check out sites about making jewellry. Lost of good stuff. For a bit of inspiration a bit closer to home , check out this site http://modelengines.info/naphtha/Main/ Lots of great pics on soldering up some bits for a VERY nice engine. If the link doesn't work, just GOOGLE "naphtha launch engine". One of the most useful tips (shown in the link above) is the use of small pieces of solder placed at the joint. These are, as I recall, called "pallions" in jewelry-speak and the "so what" is that they allow you to better control the amount of solder you're using and things turn out much tidier than if you feed solder right of the coil. Silver solder is a bugger to get off once you get it where you don't want it. An added benefit is that you don't waste as much solder which, at the price of silver solder, is a consideration. You can do small parts with a propane torch, but it is slow. In balance the chance of turning your small part into a puddle is reduced. Mapp gas is a bit hotter. Oxy something is the trick, but can be a problem with small parts unless you have the right size torch. (see jewellry stuff). Soldering on a fire brick is a big help, especially if your set up is heat limited. As with all soldering, clean parts with good fits, the right flux, the right solder, and enough heat (but not too much) and you can't fail (as eaily). Try it, it's fun and allows some cool parts to be made w/o castings.

 

[sunworksco]

For soldering small parts, I use a MiniFlam torch.
It is the closet thing to laser!
Regards,
Giovanni

View attachment EZ-PBT.pdf

 

[RMS]

Hi Dan,

One thing I would like to point out when silver soldering parts is to keep all parts to be joined clean of all oil and even finger prints (even if hands are clean)! Then you will need proper flux and filler rod dia. as pointed out, next is a flame that will give the correct amount of heat. If these are small parts that will be less of an issue, but also something to consider. But my point is just make the joint CLEAN!

Rob

 

[Jasonb]

Although a UK supoplier its worth having a read of teh three sections under the lefthand box "Why Braze"

http://www.cupalloys.co.uk/

One note of caution about jewelry sites, they tend to use a higher silver content than us particularly if the work is to be hallmarked. If the solder is listed as Hard, medium, easy or extra easy then its a jewelry solder.

Jason

 

[rklopp]

I made a huge leap in my ability to silver solder successfully when I started surrounding the work being heated with refractory brick. I can easily get away with just a propane torch. I got the brick at a local pottery supply place.

 

[Generatorgus]

I picked up the silver soldering thing quite a few years ago, when I decided to EXPAND my out of control hobbying by making silver jewelry. All of the replies here are golden, good advice. At that time I was lucky enough to find a mini acetyline jewelers torch at a flea market. It is the nuts, as you can vary the size of the flame down to pin head, great for real small stuff and detailed work, as well as a lot of larger things. When I got into model making, some years later, my little torch allowed me to glue bits and pieces to come up with these and quite a few others for a 1/12 scale (doll house standard) working model water wheel mill I decided to build. Lots of fun. Twenty years later, I'm only on my third roll of silver solder, a little goes a long way. Got the last roll off of fleabay, along with the proper flux.

Plain old steel, with some parts made of wood and brass, allmost all of it handwork. Of course, the wood was the most difficult to solder. : No, they don't run, they're just for looking, part of the big picture.
GUS

 

[Rustkolector]

Nice work Gus. If you are going to Cabin Fever in two weeks, you ought to bring these along.

Jeff

 

[Mainer]

Kozo Hiroka (which is spelled incorrectly...) has had some excellent explanations of silver soldering in the course of his various locomotive-building series. If I'm remembering correctly, the instructions for his 3/4"' scale Pennsy Switcher has a particularly good writeup.

 

[dnp101677]

Thanks for all the great replies! Gus, I too would love to see these at Cabin Fever if you're coming. Nice Work!

So if I understand correctly. I need to buy the things on the list below

1. Torch - I'm not sure of I should buy a butane or propane. It seems that maybe I will need both and that the size of the work which will be soldered has a lot to do with whether or not one would use propane versus a smaller butane torch.

2. Flux - I think I will use Deanofid's suggestion and get mine here...http://sra-solder.com/product.php/6073/96

3. Flame Brick - I am going to check with a local mason in my area for some of these.

4. Chemicals - I see a lot of references to Sulphuric Acid. Is this all I need? I think I can get this at Lowes, right? Do I just dip my parts in before and after?

5. Silver Solder - I am still not sure what kind to get. I have some small brass part I am soldering together (.250" diameter). Can someone suggest any specifics of what I need for this? It seems like there is a lot to choose from with the actual solder.

Is there anything else that I will need to get started? I want to just set up a test station to try and get the hang of it. Thanks again for all the feedback. Your willingness to share your experience saves me a lot of time, I am sure of that!

 

[RMS]

Been a while since I have done silver braze, but I thought this was a good guide:

http://www.silfos.com/htmdocs/product_support/alloy_selection_guide.html

But I would go with what Dean suggested bellow for solder and flux, I think .031 or .025" dia. sounds about right as well as the brands he posted.

Rob

 

[Jasonb]

Beware the Silfos its not the same type of silver brazing allow, fine for refridgeration, Heat & Vent but not really ME particularly boilers.

1. I would stick with propane it ha sa higher calarific value

2. I don't know the US makes but that loks fine, buy solder & flux from teh same suppliers

3. You do not want firebricks that are used in the back of a fireplace you need leightweight bricks which will reflect the heat not absorb & store it. In the UK we use these

4. You want to dilute the acid, citric acid is another option and a bit safer though you will need to pickle for a bit longer

5. The BAg-45% will do, probably 1/32" wire for that size part. The BGa5-45% if you want cadmium free but it does not flow quite as easily

6 small fine brass or steel wirebrush for cleaning parts don't use abrasive papers

J

 

[zeeprogrammer]

3. You do not want firebricks that are used in the back of a fireplace you need leightweight bricks which will reflect the heat not absorb & store it.

Darn it. I just spent $1180 to get 8 split firebricks.
The guy gave me the firebricks. The $1180 was to get him out to repair the fireplace.

Probably fine for the kind of brazing I expect to do. Larger boilers might be a problem.

 

[Henk]

Jason,

Why the wire brush instead of the paper?

Henk

 

[Jasonb]

Abrasive papers can caus esurface oxides which restict the flow of teh solder, particularly if you pick up the first dirty old bit that comes to hand.

Have a read of the "Best Brazing practice" in the link I posted earlier it mentions this and also firebricks.

Jason

 

[Generatorgus]

Dan, this is the stuff I bought on Ebay, 50% silver, works great and flows nicely.

I agree with Jason, the alloys in the 45% and 50% range work very well. This one is cad free. The process of soldering is pretty much summed up, clean things well, apply the flux wait for the it to melt into the work before you apply the solder. The snips in the picture are flattened wire and great for small work also a good way to control the amount of solder you apply. They will usually stick to the hot flux, but gravity is good too. The flux is water soluable and can be diluted and applied judiciosly with a small brush, this also helps with over soldering the piece. For larger work I just heat the wire a little and dip in in the flux. If you dilute the flux, it will have a tendency to move your work piece as the water boils out, sometimes cured by gently heating so as to let the steam escape slowly. As for cleaning, I used to pickle all of my jewelry work, but on the models I just give the work a quick shot in the sand blaster. The blast also helps the paint to adhere.
Jeff and Dan, I'll be there Sunday, just lookin around, as I always attend the winter engine show at Jacktown on Saturday, but it would be nice to look you guy's up at the Expo. I've been torn as wether or not to just skip J-town, and show at the Expo, but I have a lot of freinds at the snow show. Lately I've been thinking it would be a lot of fun, maybe next year. I've had the mill set up there once and had a good time, it showed well.
GUS

 

[GWRdriver]

Zee,
All is not lost . . . I have used common residential firebrick (containing clay) as the floor of my brazing hearth for many years. This works well for a base and supports weight and will withstand impact but has little insulating value. The "brick" for insulating value is ceramic product called light-weight refractory firebrick. This is a light cream in color (see pic) and is primarily composed of silica. This brick contains no clay and there are various refractory ratings up to 2800F.

Re Jason's recommendation for 1/32" wire to start out . . . No doubt eventually 1/32" wire will be useful for small assemblies but if you plan anything larger I would recomment using a larger wire, 1/16" or larger. It's not a matter of conserving or using less, a joint is going to need what it's going to need, it's a matter of adequate supply to the joint. You will be surprised how quickly 1/32" wire will be consumed and once the joint is up to soldering temperature you cannot be bothered to stop the process while you straighten out another foot of wire. I think a good plan would be to prepare lots more 1/32 wire than you think will be needed, or have a little of both on hand.

 

[Henk]

Jason,

Thanks. I still don't fully understand why (if indeed the paper is fresh) but the rest of the writeup seemed good, so I'll just go along.

Henk

 

[shred]

I'm not an expert but have done this a few times, so hopefully still remember what I had to learn...

2nd Harry on the regular firebricks being usable. My brazing hearth is made of about seven of them-- two or three on the bottom, two on the sides and back. I do have one of the soft insulating bricks I often use as a platform, but the regular ones can be used for small to medium parts. Someday I'll get more of the soft ones, but I'm in no hurry. Sometimes I've had to make 'caves' of the bricks to get a bigger part up to temp.

I like the 1/32" wire though, since I'm a big fan of cutting rings and lengths of it to lay along joints prior to heating the whole lot.

I did a couple test pieces getting the hang of it, but overall it's pretty simple-- clean everything (workpiece AND solder), don't touch it with bare fingers anymore, flux everything (workpiece AND solder), heat it lightly to dry the flux, then heat the heck out of it with a propane torch, trying really hard not to apply the flame directly to the fluxed area. Heat until you can just about see what you're doing by the light of the workpiece. Seriously-- you'll be at 'cooked carrots orange' before the solder flashes into liquid. Let it cool for a bit (more for steel and materials that don't need to be heat-treated), drop into some water, then into the pickle.

Here's a little video I did a while back:

[ame]http://www.youtube.com/watch?v=WEtUJQuK-z8[/ame]