## PSN-L Email List Message

Subject: Anniversary clock spring
From: tchannel1@............
Date: Sat, 15 Dec 2007 11:40:31 -0700

```Hi Folks,  This is an observation and a question.  I have an Anniversary =
clock, perhaps also called a 500 day clock, as you only need to wind it =
once a year, or so.   I know very little about clocks, but have worked =
on a few clock movements and escapements.   I have some old clocks which =
are 8 day movements.   I wondered why the big difference in power =
consumptions, and spring properties between the two types.

The 8 day movements use a short pendulum which is maybe 1/2 second =
natural period.  The anniversary clock has a short spring, instead of a =
pendulum, which is  like a flat thread.  This spring is fixed at the top =
and has four masses, brass balls on the free end.  One period of this =
spring is about  8 seconds.   The mass in motion, twist the thread like =
spring, until the power of the spring stops the mass, and swings it in =
the opposite direction.  A different coiled mainspring then add a kick =
to the mass and the cycle repeats.

Always looking for different ways to obtain a 20 second period, I took a =
band saw blade, cut it and suspended it from my shop ceiling.  It now =
hangs similar to the thread like movement spring of the anniversary =
clock.  At the bottom of the 72" band saw blade, I attached a 36" =
yardstick.  This now looks like an inverted "T".   I added a mass to =
both ends of the yardstick.  I twisted the spring and released it.   I =
found it rotated back and forth and it period was about 8 seconds.  I =
keep adding equal mass to both end of the yardstick, and the period was =
24 seconds.

The yardstick seems to always come to rest at the same point, as the =
spring wants to untwist.

My question:  Has anyone tried this approach?   If so,  could anyone =

Thanks, Ted

Hi Folks,  This is an observation and a question.  I have =
an=20
Anniversary clock, perhaps also called a 500 day clock, as you only need =
to wind=20
it once a year, or so.   I know very little about clocks, but =
have=20
worked on a few clock movements and escapements.   I have some =
old=20
clocks which are 8 day movements.   I wondered why the big =
difference=20
in power consumptions, and spring properties between the two types.
The 8 day movements use a short pendulum which is maybe 1/2=20
second natural period.  The anniversary clock has a short =
spring,=20
instead of a pendulum, which is  like a flat thread.  This =
spring is=20
fixed at the top and has four masses, brass balls on the free end.  =
One=20
period of this spring is about  8 seconds.   The mass in =
motion,=20
twist the thread like spring, until the power of the spring stops the =
mass, and=20
swings it in the opposite direction.  A different=20
coiled mainspring then add a kick to the mass and the cycle =
repeats.
Always looking for different ways to obtain a 20 second period, I =
took a band=20
saw blade, cut it and suspended it from my shop ceiling.  It now =
hangs=20
similar to the thread like movement spring of the anniversary =
clock.  At=20
the bottom of the 72" band saw blade, I attached a 36" yardstick.  =
This now=20
looks like an inverted "T".   I added a mass to both ends of =
the=20
yardstick.  I twisted the spring and released it.   I =
found it=20
rotated back and forth and it period was about 8 seconds.  I keep =