This is a clock I had never before seen.
It is fully marked for WWII Air Ministry and is of Swiss manufacture.
Until I could get it fully disassembled, I at first thought it was a British Copy
made under duress. It is NOT a Lecoultre and it is of lesser quality in
design and execution. Kind of reminds me of Swiza. But the only
mark is "Swiss" with absolutely no maker's ID. Interesting.
The first problem was to uncase the piece.
The TOT knob on the left is not the typical pusher type, but you push down
vertically. The screw for that knob was badly rusted and the head was
deformed. There was no room to mount the piece in a vise and mill the screw out.
Obviously, the knob and the case had to be preserved intact.
In consultation with owner, it was decided
that since I could duplicate the TOT operating arbor I should part the arbor
just below the knob. I then dissolved the remaining steel in the
knob, preserving it.
After the movt was uncased, an it was
revealed that inexperienced
workman had destroyed the balance fork. This kind of thing happens with
people who have no idea of the effort required to make something. It was
not a major issue when parts were available; but now that parts for vintage
pieces no longer exist and parts for more modern pieces are becoming depleted,
such damage must be avoided.
The pallet fork safety horn is crushed by poor handling
and using the Nikon optical comparator to select a replacement candidate
While I have made most watch parts I have
not occasion to make a pallet fork (thankfully). And if it was required
for this piece, the cost would have been a show stopper. Fortunately, I
know something about how the Swiss cartels worked and knew that there is a limited
selection of standardized escapement sets that were purchased from one
supplier. I have been in business for almost 40 years
and years ago started purchasing material such as jewels, staffs and
escapement parts in bulk. So using the optical comparator I was able to select a proper candidate
even though I had to enlarge the slots to take the original pallet jewels.
Another issue became apparent after the work
was "completed". Testing revealed a serious fault in the TOT
(time of trip) function. In most TOT clocks, the center seconds chrono (elapsed time)
is independent of the 12 hour TOT function. As a cost savings, the
operating lever I had to make operated both functions as one unit.
Close inspection revealed that the beak of the center seconds intermediate
wheel lever had been shortened. This meant that the intermediate wheel
could never lift off the center seconds runner even when the TOT was paused or
reset. Of course, this stops the clock. This was apparently done
by someone who did not know the theory of chronographs and thought they could
make the center seconds run continuously. If you have a better theory
let me know.
We would have preferred for me to make
the upper block of the lever, but cost was becoming an issue. There was spare height
on the column wheel. I made a patch for 1/4 the cost of a new lever that
fit over the shortened beak. If an owner in the future choose, this can
be used as the template for making the new lever upper block. But since it now
functions, that of course is unlikely.
The machined and hardened
"patch" pinned to the intermediate wheel
The repaired intermediate wheel
lever installed in the timepiece
The new operating arbor was manufactured and
installed. Rather than use the cross pin to keep the knob oriented (an
apparent cost savings) I tapped the hole in the block and used a grub screw.
this will avoid a situation in the future similar to what I encountered.