"gareth evans" wrote in message
...
On 08/04/2021 13:59, NY wrote:
We have a (clockwork) chiming clock. A few months ago it was cleaned and
re-fettled by a clock restorer (previously it didn't go at all). After
several months, it has begun stopping. Clearly it will need to go back
to the repairer.

But the exact symptoms are intriguing. I've noticed it always stops at
12.57. The hour-chiming mechanism kicks in at an indicated time of
xx:00, several minutes later. The clock only ever stops at night - ie
00:57 rather than 12:57. It also only does this every few days, not
every night. During the day it runs perfectly.

Firstly, do you mean the strike (counting out the hours) rather than the
chime (The quarter hour bongs)?

I suspect that the problem will lie with the date advance at midnight;
the hour hand rotates twice in 24 hours, but there is another wheel
geared down at 2:1 to advance the date. I suspect that the spigot
that advances the date wheel is riding onto the surface of the date
wheel instead of pushing it along.

The clock does not have a date display.

It has two chiming mechanisms: the Westminster chimes every quarter hour and
the striking on the hour. When I said "the hour-chiming mechanism kicks in
at an indicated time of xx:00", I meant that start of the chiming sequence.
The bongs follow a few seconds later after the chimes have finished. Without
a seconds hand I can't say how accurately the start of the chiming sequence
or the start of the striking correlates to the xx:00:00, but I think the
minute hand is pretty close to the 12 position. I imagine that's one of
those things which a clock repairer adjusts. He'd probably need to remove
the hands to remove the face so he could get access to the front face of the
mechanism. Given the cost of the repair, it may have been a complete
dismantle, clean and reassemble, maybe even with re-turning some of the
shafts and fitting correspondingly smaller bearings - but that's all
supposition.


Anyway, it's not date advance because there is no date dial. Do date advance
dials move continuously as the day progresses, or do they move suddenly from
20 to 21 etc at midnight? From your description of "geared down by 2:1" I
presume it's the former.


At least the clock hasn't started chiming 13 so I won't be finding a
Midnight Garden anywhere - and anyway, my name's not Tom ;-)