Eventually it also happened to me. I broke a 0,7 mm drill in an
almost finished piece of sterling silver. Remembering the matter was
discussed here about two htree months ago I searched the archives. I
have now tried to boil the piece in alum with no reaction, same with
10 and 20 per cent hot sulphuric and hydrocloric acid. The drill is a
swiss Antilope mark, saying good for 30.000 RPM max, Acier PM. I’m
afraid the last means acid resistent, at least it seems to be.
Anybody out there got an idea? Any help would be highly appreciated.
Kind regards from cold, windy Denmark
Niels Lovschal, Jyllinge, Denmark