Annealing of Silver

I want to run some .999 silver bars through a slip roller to reduce their thickness. My intent is to try to do some coining in the style of
medieval moneyers, using homemade dies. I assume that the rolling will harden the silver, but how much? What would be a good technique to anneal them so they will be dead soft? I don't have any ovens that can go over 550 F, so the operation would have to be done with a torch, I suppose.
Also, where can I get a punch that would allow me to make 1-2" diameter blanks? Would a standard arch punch work (on the annealed metal), or would it wear too rapidly?
TIA, Joe
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After one or two passes through the rolling mill, the silver will become quite hard. Anneal the hardened silver piece by heating it till it is red hot, then quench it immediately in cold water. Dry the silver well before passing it through the roller again. If you roll the silver through the rolling mill without annealing the silver, the silver may pull apart.
There is a press called Bonnie Doon that is used to make medallions such as you are thinking of doing. I don't know much about the Bonnie Doon press, but you can do a Google search if you want to learn what they have to say about pressing out medallions.
Steve

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I forgot to include that I heat the silver with an acetylene torch -- only to red hot lest it melt. Be careful to move the flame over the piece of silver to heat the silver uniformly.
Steve (hmm, how'd I become John Smith?)

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John Smith wrote: (clip) Anneal the hardened silver piece by heating it till it is red hot, then quench it immediately in cold water. (clip) ^^^^^^^^^^^^^ Quenching does not do any harm, but it is not necessary.
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If the heated piece of silver isn't quenched in cold water, how long would one have to wait before the silver would cool enough to be passed through the rolling mill again? It takes a lot of passes to carefully roll a silver ingot into sheet of a desired thickness. Joe's ultimate goal is to stamp a medallion out of dead soft silver.
Steve (aka John Smith?)
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There is no real reason to wait. The mill will cool the silver quite adequately.
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Will the red hot silver ingot take the temper out of part of the rolling mill roller, leaving a soft spot?
Steve (aka John Smith)
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Hmm, I missed the "silver bars" bit. I'd say probably not, but it's on the edge. If they are large, then a bucket of water is probably a good idea.
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Only heat to a dull red, just above black heat,do not hold at heat longer than nessary to prevent grain growth. Water or pickel quench will make it a bit softer than air cooling. You should be able to reduce thickness by at least half between anealings. Roll in one direction only between anealings. You can forge it thiner with a hamer first if you want, then roll to even up the surface.
Les
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We do this on a regular basis. There is also a Yahoo group devoted to doing this "sca_moneyer". We usually get about 3 passes before you have to anneal, some times 2. We used to use the stirrup punches, but they are not great. What works better and are commonly available, are shim punches. I also recently noticed one (quality unknown) at harbor freight "46628-3VGA". ~ $12.00.
Our group has had custom punches that are essentially the same thing, (in a single size) made.
jk
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We do this on a regular basis. There is also a Yahoo group devoted to doing this "sca_moneyer".
Annealing: You want to heat it up to where it is just red, and then let it cool. We usually get about 3 passes before you have to anneal, some times 2.
Punching We used to use the stirrup punches, but they are not great. What works better and are commonly available, are shim punches. I also recently noticed one (quality unknown) at harbor freight "46628-3VGA". ~ $12.00.
Our group has had custom punches that are essentially the same thing, (in a single size) made.
A 2" diameter is HUGE for hand striking, 1" is pretty big but doable. It depends of course upon how big a hammer you can manage. Some people in our group prefer a 4 lb hammer swung two handed, I use an 8lb sledge that I have cut town to about 1 foot.
Striking a lot of coins also works best as a 3 man operation. A placer, a die holder and a striker.
Where are you located?
jk
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wrote:

"When I nod my head, hit it real hard..."
(Sorry. Couldn't resist.)
Jeff
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Most slip rolls won't be stiff enough to roll down silver ingots. Maybe a big industrial model might work. Jewelers use a rolling mill that is considerably stiffer in construction than a typical small slip roll. What is the thickness of your bars? I have a medium-sized Durston rolling mill, and the max it can handle is about 6 mm thick. It has a 4-1 reduction gear, and still requires a LOT of elbow grease to roll wide ingots. It has 130 mm wide by 60mm diameter rolls, in a heavy steel plate frame. Compare that construction to a typical slip roll, and you can see the difference.

Yes, you will need to anneal, generally every time you reduce the thickness by 1/2. Heat to dull red heat and quench in water once the glow is gone. If you don't quench, the silver doesn't get nearly as soft.

The arch punch will only work on very thin metal -- coin blanks are too thick, IMO.
Regards,
Bob

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Joe, Pure silver may not work harden unless it is extremely abused. That being said, heat to 1200 F and quench to soften. If it is pure, this will not create an oxide layer like sterling would have. If it was sterling, a further soak at 600 F for 1 hr would harden it. Be careful heating, melting is at 1760 F.
IANAJ (I am not a jeweler)
Elliot

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Pure silver (at least 99.9) will certainly work harden.
jk
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0.999 silver ingots, both Englehardt bars and "rounds" (ingots in a round form sometimes called "trade dollars") will certainly work harden after about three passes through the rolling mill in which the rollers are adjusted a little bit closer each time. The silver metal being formed into sheet work hardens. Any more rolling and you chance pulling the metal apart.
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Why do you want to use fine silver? It will wear very fast. Also when annealing you need to protect it against fire staining/scaling. 99.9 will not fire stain like sterling silver (95% silver 5% copper) but will some. You can prevent by using a 50% mixture of alcohol (denatured hardware stuff) and boric acid (roach kill). Apply the mixture with brush, lite up and let alcohol burn off. Then using ox/acty torch with large bushy flame and little on the acty heat to dull red. Quench after about a minute so the silver does not tear or crack when you pick it up. Use a pickle to clean the silver before you roll.
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Well, we don't find that it fire scales at all.
We use fine silver for a few reasons. It is a little easier for us to obtain locally, it doesn't fire scale, and because it is slightly softer when annealed, and hence strikes better. For what we do (making coins) wear is not really a concern, but the striking process does work harden them, some what.
snipped-for-privacy@comcast.net (Warren Townsend) wrote:

jk
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Can I ask you to post some pix when you have struck some coins? (Of the dies, too - or better still, the whole process?)
This sounds like a lot of fun.
Jeff
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