Ted--there is some neat physics in the inverted T torsional balance.  =
The increase of period with increased masses added makes for a nice =
graph in a physics lab, and there are related aspects of interest.  =
Perhaps stability would be a big problem, but set it up with a damping =
mechanism, and give it a try.         Seasons Greetings    Jim Lehman
  ----- Original Message -----=20
  From: tchannel1@...............
  To: psn=20
  Sent: Saturday, December 15, 2007 1:40 PM
  Subject: Anniversary clock spring


  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








Ted--there is some neat physics in the =
inverted T=20
torsional balance.  The increase of period with increased masses =
added=20
makes for a nice graph in a physics lab, and there are related aspects =
of=20
interest.  Perhaps stability would be a big problem, but set it up =
with a=20
damping mechanism, and give it a=20
try.         Seasons=20
Greetings    Jim Lehman

  
----- Original Message ----- 
  From:=20
  tchannel1@............ =

  
To: psn 
  
Sent: Saturday, December 15, =
2007 1:40=20
  PM
  
Subject: Anniversary clock =
spring
  


  

  
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=20
  wind it once a year, or so.   I know very little about =
clocks, but=20
  have worked on a few clock movements and escapements.   I =
have some=20
  old clocks which are 8 day movements.   I wondered why the =
big=20
  difference in power consumptions, and spring properties between the =
two=20
  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=20
  motion, twist the thread like spring, until the power of the spring =
stops the=20
  mass, and 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=20
  band saw blade, cut it and suspended it from my shop ceiling.  It =
now=20
  hangs similar to the thread like movement spring of the anniversary=20
  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=20
  mass to both ends of the yardstick.  I twisted the spring and =
released=20
  it.   I found it rotated back and forth and it period was =
about 8=20
  seconds.  I keep adding equal mass to both end of the yardstick, =
and the=20
  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,=20
   could anyone direct me to more information about it on the =
internet?
  
Thanks, Ted