I’ve been trying to solder a U-shaped piece of wire to the top of a
dapped 1930 Canadian 25-cent coin, which is 80% silver. I don’t know
what metals represent the remaining 20%. I’m using hard silver sheet
solder, and can’t get the solder to flow.
I’ve tried soldering the pieces lying flat on a charcoal block and a
honeycomb board, from otherneath on a tripod screen, and with the
coin held vertically in a third hand, and have tried Battern’s liquid
flux and a paste flux. I’ve cleaned the pieces thoroughly with pickle
and steel wool, so I don’t think cleanliness is the issue. And I
smoothed the top rim of the coin to remove the rim grooves.
I think the problem is positioning, or that my wire ends don’t
flawlessly fit the coin rim surface, or something to do with the
metal content of the coin. Once I (accidentally) got the metals red
hot, but the solder remained solid.
What is the best way to hold/position the dapped coin and bail wire?
Where is best to place the solder chips? And how can I get the wire
ends to more exactly fit the curved coin rim? I tried hand-filing and
using a flex shaft grinding wheel, but the fit was not perfect.
Any advice you can provide will be much appreciated.