Measuring grandfather clock pendulum, how?

[Royce Jatko]

Hello,

I've just acquired a Ridgeway grandfather clock. The movement is marked
Germany, but I can't find a maker's name or model number anywhere, I suspect
Hermle, but am not certain. On the back lower right corner it says "PL 85
CM". I take this to mean pendulum length 85 centimeters (app. 33.5 inches).
The pendulum which came with it is considerably shorter, just 27 inches
total length (tip to tip). However, I don't know exactly how it should be
measured, to the bottom of the bob, the tip of the threaded rod, etc.? I
haven't been able to find this info online. Thanks!

Royce

[Murray]

27 inches sounds about right. Put the pendulum on, and measure from
the suspension post on the back of the movement, to the centre of the
pendulum bob. Should be about 33 inches. If the clock has a lyre
pendulum (several metal rods=some mass that cannot be ignored) then
the actual length will be somewhat longer, as it is the theoretical
length to the CENTRE OF GRAVITY OF THE PENDULUM which is to be 85 cm.

[John James Cahill]

> >
> >I've just acquired a Ridgeway grandfather clock. The movement is marked
> >Germany, but I can't find a maker's name or model number anywhere, I suspect
> >Hermle, but am not certain. On the back lower right corner it says "PL 85
> >CM". I take this to mean pendulum length 85 centimeters (app. 33.5 inches).
> >The pendulum which came with it is considerably shorter, just 27 inches
> >total length (tip to tip). However, I don't know exactly how it should be
> >measured, to the bottom of the bob, the tip of the threaded rod, etc.? I
> >haven't been able to find this info online. Thanks!
> >
> >Royce
> >
> >

> >*******
I have the same problem Royce has with a Ridgeway movement. I
contacted customer service at Ridgway who informed me the proper
pendulum length was 27 inches. They also told me to contact LaRose
because Ridgeway no longer stocked parts for my clock, which also has
a German movement without id numbers.
LaRose said the pendulum they had was 29 inches, but that it
could be cut down. I did measure 29 inches as the length of the
"stick' and cut that two inches shorter. Even with the bob at its
highest point, the clock still runs too slow.
A further request to Ridgeway about exactly where and how to
measure the pendulum has not produced any additional information.
BTW, my clock is a Grandmother, not a Grandfather. What to do.

John James Cahill, Mt. Vernon, VA
stick

[The Baron@flash.net]

It seems as though you have solved your problem. Just keep cutting the
rod till your clock rates correctly. Or, you might count all the gear
teeth and calculate the pendulum length. A problem with pendulum length
numbers on the plates is that they may or may not reflect the true length as
manufacturers often supply the pendulum with the clock. Some fancy
pendulums are much longer than their true length. This is due to a center
of gravity not located near the center of the bob.
This can work to your advantage by adding weight above the bob will change
the ''length'' and the rate of the clock.
"John James Cahill" <JayK...@aol.com> wrote in message
news:7751939b.01090...@posting.google.com...

[John James Cahill]

"It seems as though you have solved your problem. Just keep cutting
the
> rod till your clock rates correctly. Or, you might count all the gear
> teeth and calculate the pendulum length

******
Neither with horses nor with clocks am I one to go counting teeth
<vbg>. As a result, I guess the idea is to continue cutting off the
''stick'' (is that what the Baron means by the rod?)

Any suggestions as to how much or how little to take off next time. I
ASS u ME I should keep the bob adjustment as high as it can be until I
am very much in the ballpark on the rate of the clock, as I can always
take a little more off the stick, but cannot add any back. Does that
make sense to an expert?

I have no experience in these matters, obviously. Thanx for your
help.

[The Baron@flash.net]

Yes, a little at a time. Usually a bob can be adjusted about one inch,
trying removing in one inch units. A pendulum is composed of (and generally
referred to as) a bob and a rod, regardless of material.

"John James Cahill" <JayK...@aol.com> wrote in message
news:7751939b.01090...@posting.google.com...

[John James Cahill]

Thanks, Baron,

I shall shorten the pendulum by one inch and see what happens. I
shall keep you all posted.

[The Baron@flash.net]

Please do keep us informed and insure that the pendulum crutch is connected
to the suspension spring and that the pendulum rod is connected to the
crutch.

The Baron

"John James Cahill" <JayK...@aol.com> wrote in message
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