## PSN-L Email List Message

Subject: Re: Anniversary clock spring
From: "Les LaZar" llazar@..................
Date: Sat, 15 Dec 2007 16:01:51 -0800

```How would a seismic wave, passing by an inverted T torsional balance, =
impart any torsional motion to the horizontal bar and the masses?  Just =
wondering.

Les LaZar

----- Original Message -----=20
From: Connie and Jim Lehman=20
To: psn-l@.................
Sent: Saturday, December 15, 2007 2:56 PM
Subject: Re: Anniversary clock spring

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 =

Thanks, Ted

How would a seismic wave, passing by an =
inverted T=20
torsional balance, impart any torsional motion to the horizontal bar and =
the=20
masses?  Just wondering.

Les LaZar

----- Original Message -----
From:=20
Connie and=20
Jim Lehman
To: psn-l@..............
Sent: Saturday, December 15, =
2007 2:56=20
PM
Subject: Re: Anniversary clock=20
spring

Ted--there is some neat physics in =
the inverted T=20
torsional balance.  The increase of period with increased masses =
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=20
some old clocks which are 8 day movements.   I wondered =
why the=20
big 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=20
is fixed at the top and has four masses, brass balls on the free =
end. =20
One 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=20
the mass, and swings it in the opposite direction.  A =
different=20
coiled mainspring then add a kick to the mass and the cycle=20
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"=20
yardstick.  This now looks like an inverted "T".   I =
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 =
seconds.  I keep adding equal mass to both end of the =
yardstick, and=20
the period was 24 seconds.
The yardstick seems to always come to rest at the same =
point, as=20
the spring wants to untwist.
My question:  Has anyone tried this approach?   If =
so,=20