Hi Markus,
Thanks for the note. I think I’ve seen what your describing but
this is different. The coin is about 2-2.5mm thick total. The
center of the coin was removed with a lathe to about 1.75mm.
leaving a 5.mm rim. The jeweller must have use a small mill to
under cut the rim at the six and twelve o’clock positions with a
wheel bur or end mill. There is a precision fit inner ring
(1.5mm deep by 3.mm wide and 25mm in diameter) which has an
offset carriage hinge that fit into the six o’clock recess. The
hinge is U shaped with hinge tube at the top of one side of the
U. The other side of the U is soldered to the coin lid to allow
it to close flush with the coin surface. The is a L shaped
spring that pops out the coin lid about 2.mm after the catch is
pressed. The spring is spring wire .5mm. This still works fine.
The catch on the other hand is at the 12 o’clock position. This
is my problem area. There is a jump ring solder to the top with
a diamond bail. Between the legs of the jump ring is flush post
that is to be depressed with the sharp end of the bail, similar
to pocket watch in theory. On the under side of the lid was a
wedge shape, heal towards to the rim. The heal also had
horizontal groove. The plunger once removed looks like a dust pan
from the recessed area at 12’. At the top of the shoulder of the
dust pan were wire springs coming out both side. The precision
cut rim has cut out at the 12’ to accommodate the catch
mechanism. I think I’m going to replace it with a T-pin and
sliding jump ring style lock. But if you ever run into any books
with diagrams for these whacky watch locks, let me know. Thanks.
Jim alpine@hay.net let me know