On 11/24/2012 6:24 AM, klem kedidelhopper wrote:
Sorry to post this question here but I really didn't know where else
to address it to. It is obviously not electronics related however I
was hoping that someone could never the less help me.

I was given this really nice wall clock. The clock was missing the
pendulum and the winding key when I received it. The clock is supposed
to chime once on every half hour and then appropriately the correct
number on every hour.

A friend who does clock repair gave me a small pendulum and a key. He
said the size of the pendulum is not too critical and so he thought
that the one he gave me should work. Well it does however the clock is
really running slow. It sounds like it's in perfect beat though, and
although I've run the pendulum up the stick pretty high now it's still
a few minutes slow over a two hour period. I've tried adding some
weight to the pendulum but that didn't seem to make any difference.

The clock doesn't look gummy but it is dry. I had planned to spray the
movement down with a no residue cleaner and then oil every thing that
moves with a light oil. I just didn't want to possibly introduce
another problem into the equation before I fix the current one.

So I had some questions. i don't know what this pendulum that he gave
me is from. Is the pendulum weight and length critical? My friend says
no, however the loss of several minutes over the course of two hours
seems really excessive. Is it possible that the incorrect pendulum is
causing the current problem and that perhaps there might not even be a
problem if I had the correct pendulum? Could the need for a cleaning
and lubrication cause such a speed error?

The movement seems to be a fairly nice one and primarily is of brass.
Above the manufacturers name, (Mason and Sullivan Co.) there is a
number 75. Below that it reads: "no (0) jewels" next line: "Made in
West Germany" Below that: " unadjusted" and below that : "141-070".
Then on the bottom line there is the following:

29cm
----------
130.37

If anyone has some advice for me as to my questions and how to proceed
with this project I would be very grateful. Thanks for any advice on
this. Lenny

The length of the pendulum should be reduced. Usual there is a nut at
the underside of the pendulum. Turn the nut to get the weight closer to
the clock. T = 2 Pi sqrt(L / g)
where L is the length of the pendulum and g is the local acceleration of
gravity. It is independent of the mass.

See https://en.wikipedia.org/wiki/Pendulum