NY wrote:
I have a granddaughter clock and I'm having great difficulty adjusting it so
it keeps good time. The pendulum bob (a metal disc) sits loosely on a
threaded rod which has lugs allowing it to sit on the oscillating part of
the clock mechanism. The bob rests on an adjustable nut on the rod, which
allows the pendulum to be lengthened or shortened.

It used to lose about 5 minutes a day, but I've progressively wound up the
nut 1/2 turn at a time, to shorten the pendulum so it has a shorter period.
I'd got it almost right, but then I went backwards: a further shortening
made it run *slower*. I wound the nut a full turn shorter which was
evidently too far (the clock ran too quickly), but when I backed it off 1/4
turn, it started to run a lot slower than before I originally adjusted it.

Part of the problem is that it is necessary to turn the clock round to get
at the back, and then unhook the pendulum from its mount on the mechanism to
be able to get at the adjustment screw. I'm wondering whether it doesn't
always reseat to the same position and/or slight differences in how the
clock sits on the floor are making things non-reproducible.

The floor is modern hardwood tiles laid on a concrete floor that was
levelled with self-levelling compound when we had building work last year,
so it's not the problem of a sloping floor or a carpet that is thicker near
the walls than a few inches into the room.

Any suggestions?



My suspicion is the escapement is worn so the going train ( the gears
which, in simple terms turn the hands) arent being released consistently
or imparting the impulse to the pendulum consistently.

When the pendulum is grossly too long, the wear is masked. As you correct
the length, the wear problem dominates.