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 =
direct me to more information about it on the internet?

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 = adding=20 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=20 spring wants to untwist.

My question:  Has anyone tried this approach?   If so, =  could anyone direct me to more information about it on the = internet?

Thanks, Ted


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