Solder Silver to Copper & Brass

[Fox Creek Kid]

Anyone here ever soldered silver to brass or copper? I have some Mexican silver coins from the 1800's that I am going to shape into a sight and then have them soldered into copper & brass bases.

[Scratch]

They are all non-ferrous metals so it is relatively easy job.  Not sure what kind of equipment/supplies you may have.  You can use propane if that is all you have and the sight is small.  Use a surface that will reflect heat back, I use charcoal block, but a bed of lava rocks (small size) will work. 

I cut silver solder into small pieces (snippets).  Make sure the surfaces of the metals to be soldered are square and clean.  After I apply the flux I apply some heat to the metal so the solder pieces don't dance all over the place, then lay some solder pieces on one side of the work and apply heat all around and especially on the thicker pices of metal and the opposite side of the solder.  When the temparture of the metal reaches the flowing temp of the solder the solder will flow between the metals, then pull the heat off.

If the sight blade will not sit correctly on the base you will have to either use light wire or a holding jig to secure it.  Anytime you use something to hold it, the jig becomes a heat sink so it will take more heat.

This site might help also...http://www.jewelryartistmagazine.com/tech/1298tech.cfm

[Fox Creek Kid]

Thank you. 

[Bull Schmitt]

Since the parts you are soldering are small you might find that the heat will melt both the silver solder and the parts you are working on. An alternative would be to use a low temperature solder. Some of the lead free ones are worth considering. Brownells sells some high strength low temperature solder that works fine.

[65bsaA65]

I think Bull Schmidt's suggestion is probably the way to go.  The melting temp of the silver coin and the silver solder is going to be close (depending on the alloy metals percentage in the solder) and you don't actually want to melt the base of the coin.  I don't know what your skill level re soldering is, but better to err on the colder side, cause you can always repeat the exercise if the coin isn't reduced to a blob.
A lot of years ago I made a custom belt buckle from stainless steel with an Indian head penny centered on the plate.  I silver soldered the penny to the stainless, which sounds easy in retrospect, but I spent at least 12 hours on it (counting grinding , sanding, polishing, welding the leather attachment points and the hook to the plate.  The penny was the hardest part; at least half of the total time.  I destroyed 4 Lincoln pennies before getting the heat and the technique down to the point where I felt confident to go to the Indian head.  And I had a good Victor jewelers oxy-aceteline torch to work with.
So, I would try out Mr. Schmidt's idea. 

[Professor Marvel]

Greetings Kid -
This will probably complicate matters for you, however ....
Professionals buy silver solder as sheetgoods, and cut it to very tiny squares, applied at the edges of the work using a paint brush wet with flux.
Those of us who dabble in silver work, but who are not as adept as Monsieur Scratch, like to pick up a roll of "silver bearing solder" from such sources as Brownells, Indian Jewelrs Supply or Thunderbird Jewelry.  There is less control feeding wire solder like a welder, and often makes a more noticable and sometimes obnoxious looking joint :-)

At the low end is hardware store stuff like StayBrite   which melts around 475 deg and contains roughly 62%-tin, 36%-lead, 2%-silver. Higher up the scale are various solders that contain more silver and thus are both "harder" and require a higher temp to melt. The quality materials Scratch mentioned are very high in silver content and thus require temperature that are rather close to the melting point of the parent material (ie: your coin) .    You might go here http://www.cupalloys.com/content.php for a bit of discussion on various solder alloy temperatures.  Some wire solder is available here: http://www.contenti.com/products/soldering/420-821.htm - and I can highly recommend the " Easy" which melts at    1145° F. On small work this is readily achievable with a propane or MAPP torch and a small flame or a smaller tip.

By all  means, get some scrap and practice -  I made the mistake of using a hobby grade oxy-propane torch on my first jewelry attempt and completely melted the back of a sterling  bolo tie bezel cup.

your humble servant
Prof Marvel

[Fox Creek Kid]

Ironically I just read the superb article on soldering in the new "Rifle" magazine at the newsstand. It made me realize that this would be a job for a pro.